Prerpints.org logo
Preprint
Article

An Investigation into the Efficacy of Septic Tank Systems in Removing Organics in a Subtropical Climate

Altmetrics

Downloads

114

Views

44

Comments

0

A peer-reviewed article of this preprint also exists.

This version is not peer-reviewed

Advances in Organic Solid Waste and Wastewater Management

Submitted:

19 October 2023

Posted:

19 October 2023

You are already at the latest version

Alerts
Abstract
An estimated 38 million individuals, out of a total population of around 126 million, reside in urban areas of Bangladesh. The surge in urbanization and water consumption has led to a significant rise in waterborne sanitation systems within the country. One cost-effective solution for wastewater treatment is the utilization of septic tanks, which operate as anaerobic reactors, with their efficiency being closely tied to temperature conditions. This research focuses on evaluating the organic removal capabilities of a septic tank located on the Khulna University of Engineering and Technology (KUET) campus. The results show that a septic tank's ability to remove organic matter depends on the temperature, with higher temperatures making the removal process more effective. Additionally, the Total Suspended Solids (TSS) levels were observed within a range of 110–280 mg/L, 200–1030 mg/L, 160–880 mg/L, and 190–220 mg/L for the 1st, 2nd, and 3rd chambers, respectively. The maximum recorded pH values were 7.14, 7.13, and 7.11, while the minimum pH values were 7.06, 7.05, and 7.04, corresponding to the same chambers. Furthermore, the organic removal efficiency concerning dissolved oxygen (DO), nitrate (NO3-N), and pH levels remained within acceptable limits. These results suggest that a simple treatment unit like a septic tank can effectively render previously unacceptable and unhygienic water suitable for safe disposal and potential reuse, ultimately improving the management of septic tank wastewater.
Keywords: 
Subject: Engineering  -   Civil Engineering

1. Introduction

Bangladesh, a densely populated middle-income nation in the Asia-Pacific region, faces a pressing sanitation crisis due to widespread poverty [1,2,3,4,5]. Despite efforts, the country fell short of achieving the Millennium Development Goals, with 40% of the population still lacking access to adequate sanitation as of 2015 [6,7,8,9]. To address this issue, septic tank systems have been implemented for the effective treatment of human waste [10,11,12]. Septic tanks serve as affordable anaerobic reactors for wastewater treatment. A standard septic tank system comprises two main components: the septic tank and a network of field lines that are placed within an absorption field [13,14]. It's worth noting that temperature serves as a crucial environmental factor that significantly impacts the functioning of septic tank-soil absorption systems [15,16,17,18,19,20]. The surge in urbanization and heightened water usage in Bangladesh has given rise to a proliferation of waterborne sanitation systems, yet the management of residual waste often remains inadequately addressed in infrastructure projects [21,22]. The uncontrolled discharge of wastewater and fecal sludge poses significant environmental and public health challenges in urban and suburban areas [23,24,25,26,27]. The COVID-19 pandemic has underscored the importance of maintaining effective septic tank wastewater treatment systems to prevent the potential spread of the virus through inadequate sanitation practices [28,29]. Many of Bangladesh's cities and towns are situated near swamps and lakes, which local residents often use for informal aquaculture. Regrettably, these water bodies are frequently contaminated with fecal matter, compromising water quality and negatively impacting the livelihoods of vulnerable communities [30,31,32,33]. Moreover, pollution from domestic sources further deteriorates water quality in surface water bodies and groundwater aquifers, posing threats to both natural ecosystems and public health [22,23].
In any given community, both liquid and solid waste materials, along with air emissions, are produced [25,34,35,36]. Liquid waste, commonly referred to as wastewater, constitutes the water supply used within the community for various purposes. Any water quality adversely affected by human activities is classified as wastewater [37,38,39]. In terms of its sources, wastewater can be described as a combination of liquid or water-borne waste originating from households, institutions, commercial and industrial establishments, and may also include groundwater, surface water, and stormwater [40,41,42,43,44,45,46,47]. Solid waste recycling practices contribute to a reduction in the amount of non-biodegradable waste entering septic tanks, prolonging their effectiveness, and promoting more sustainable wastewater treatment [48]. In some innovative septic tank wastewater treatment systems, solid waste is efficiently processed through anaerobic digestion to produce biogas, offering both a sustainable source of energy and an eco-friendly solution for waste management [35,49,50,51,52]. Essentially, wastewater comprises 99.9% water and 0.1% solids [18,53,54,55]. Efficient management of wastewater, or the lack thereof, exerts a direct impact on the biodiversity of aquatic ecosystems, thereby disrupting the essential systems that support life [38,56,57,58,59]. This disruption affects a wide range of sectors, including urban development, food production, and industry. Therefore, it is imperative to incorporate wastewater management as a fundamental component of an integrated, holistic, ecosystem-based management system that spans all three dimensions of sustainable development (social, economic, and environmental) [60,61,62,63,64,65,66]. This approach should extend beyond geographical boundaries and encompass both freshwater and marine environments. In regions with well-designed rainwater harvesting systems, the collected rainwater can be utilized to supplement septic tank wastewater treatment processes, reducing the overall strain on freshwater resources and enhancing the sustainability of the system [67].
A septic tank serves the purpose of acting as a receptacle for all wastewater originating from a residential dwelling and offers a basic level of primary treatment for that wastewater [68,69,70,71,72]. This primary treatment encompasses sedimentation, flotation, and a minor anaerobic digestion process [73,74]. The wastewater initially enters the first chamber of the septic tank, allowing solid particles to settle while scum floats to the surface. The settled solids undergo anaerobic digestion, which reduces their volume. The liquid component flows through a partition wall into the second chamber, where further settling occurs. The excess liquid, now in a relatively clear state, drains from the outlet into the septic drain field, which may also be referred to as a leach field, drain field, or seepage field, depending on the locality [75,76,77].
To maintain the efficiency of the septic tank, periodic preventive maintenance is necessary as solids accumulate within the tank over time [78,79,80,81,82,83,84,85]. This maintenance involves regular pumping to eliminate these accumulated solids [83,85,86,87,88,89]. In the United States, the responsibility for maintaining septic systems lies with homeowners, as stated by the US Environmental Protection Agency [90]. Neglecting this obligation can lead to costly repairs when solids escape from the tank, leading to blockages in the clarified liquid effluent disposal system. The World Bank emphasizes that one of the most significant challenges in the water and sanitation sector over the next two decades will be the implementation of cost-effective sewage treatment systems that allow for the selective reuse of treated effluents for agricultural and industrial purposes [91,92,93,94,95]. Maintaining high hygienic standards in sanitation systems is crucial to prevent the spread of diseases [21,22]. Subsurface sewage disposal systems pose the primary risk of groundwater contamination and are most concerning in densely developed suburban areas and locations with minimal soil covering bedrock [96,97,98,99]. Proper sewage and wastewater disposal is vital to safeguard public health, prevent nuisances, and protect the environment [100,101]. Recognizing the interconnectedness of wastewater management and water quality with various other issues, especially in the context of the water, energy, and food nexus, is gaining importance [102,103]. Wastewater management is a key factor in ensuring future water security in a world where water scarcity is on the rise [3,104,105,106,107].
The study aims to achieve the following objectives: measure the temperature variations in different chambers of the septic tank across different seasons; assess the impact of temperature on the septic tank's removal efficiency during different seasons; and compare the obtained values with the standard values using graphical representations.

2. Materials and Methods

2.1. Site Selection and Septic Tank Location

As shown in Figure 1, the research team conducting this investigation chose to focus their attention on a particular septic tank that is situated on the campus of KUET (Khulna University of Engineering and Technology). The selected septic tank could be found behind the Teachers Dormitory, which was more specifically referred to as Block-A.
Due to the availability of a significant volume of domestic wastewater that originated from the residential units that were located in close proximity to the septic tank in question, it was determined to be an appropriate location for the research [108,109]. Figure 2 provides a visual representation of the three separate chambers that make up the septic tank that is the subject of this investigation. Within the context of the larger system, each of these chambers serves a distinct purpose that contributes to the overall treatment and containment of the wastewater that is being processed.

2.2. Operation Conditions

The critical step in anaerobic digestion typically involves the conversion of volatile acids into methane [110]. This conversion process is carried out by methane-forming bacteria, which yield minimal energy from the breakdown of volatile acids [110,111]. The majority of the energy released during this process is harnessed for the production of methane. Methane-forming bacteria are strict anaerobes and display high sensitivity to alterations in factors like alkalinity, pH, and temperature [112]. Therefore, it is imperative to continually monitor and sustain optimal conditions within the digester to ensure their effective operation. In addition to alkalinity, pH, and temperature, there are various other operational parameters that should also be regularly observed and maintained within the ideal ranges to support the proper activity of methane-forming bacteria. This comprehensive monitoring and control of conditions are pivotal for the successful execution of anaerobic digestion processes. The operation conditions of the digestors are given in Table 1.

2.3. Septage Characteristics

Septage refers to the mixture of liquid and solid materials that are extracted from various primary treatment sources such as septic tanks or cesspools [113]. This composite substance is formed through the decomposition of organic matter and the settling of solids within the confines of the septic tank [113]. Septage is typically removed from septic tanks through a pumping process and then transported to dedicated treatment facilities for further processing and eventual disposal [114,115]. It is of utmost importance to effectively manage septage to prevent the contamination of groundwater and surface water sources, as well as to maintain the safe and efficient functioning of onsite sewage treatment systems. In septic tanks, scum accumulates at the surface while sludge settles at the bottom, together constituting a significant portion of the total tank volume, usually ranging from 20% to 50% when pumped out [76,116]. Table 2 presents the septage characteristics of the septic tank.

2.4. Wastewater Collection from the Septic Tank

The wastewater for this research was collected with great attention to detail from two separate chambers situated within the septic tank, excluding the first chamber which had accumulated a substantial amount of sludge. To safeguard the integrity of the gathered samples, containers made of high-density polyethylene (HDPE) plastic were employed. Following that, the samples were meticulously preserved for a duration of two days in a refrigerated setting maintaining a regulated temperature of 4 ºC. This step was taken to safeguard their state before proceeding with subsequent analyses. To ensure experimental assessments were conducted with precision and consistency, the samples were subsequently allowed to equilibrate to room temperature. Figure 3 depicts the wastewater collection from the septic tank.
In general, a traditional septic tank comprises four essential components. To begin with, the Soak well functions as the primary entry point for the wastewater, enabling the process of solids separation from the liquid constituent. Following this, we are introduced to the initial chamber, where the process of solid-liquid separation commences. The subsequent step is for the wastewater to be further degraded and treated in the second chamber. The treatment process is concluded in the third chamber, which guarantees that the effluent discharged from the septic tank has undergone adequate treatment to be safe for consumption.

2.5. Sample Analysis

The collected samples were subjected to analysis for pH, Total Suspended Solid (TSS), Dissolved Oxygen (DO), Nitrate (NO3-), and Electrical Conductivity (EC). The pH of the pollutant was determined using a pH meter (HACH, Model No. Sension 156). The DO meter utilized for measuring dissolved oxygen (DO) was the Hach HQ 2200. The HACH DR 2700 spectrophotometer was utilized for the measurement of nitrate levels. The HACH HQ 2100 instrument was utilized to quantify the electrical conductivity of the specimens. Gravimetric method was used for TSS measurement.

3. Results and Discussions

A number of different tests were carried out in order to determine the characteristics of the wastewater that was collected from the septic tank. The outcomes of these tests are summarized in Table 3, which can be found here. These tests examined the wastewater for a variety of different parameters.
The samples were gathered in a variety of months spread out over the course of the year. When looking at the data in the table, it is clear that the test results become increasingly variable as the temperature rises. This is something that can be observed. When compared to the third chamber, the TSS in the second chamber displays significantly higher values. The nitrate levels of four out of five samples in the second chamber were found to be higher than those in chamber 3. The recognition of the substantial reduction in nitrate levels is acknowledged.

3.1. pH

The pH of water is determined by taking the negative value of the common logarithm of the concentration of H+ ions [117]. The pH of natural water is 7.0. The pH scale is commonly depicted as encompassing a range from 0 to 14. The pH level typically influences the overall acidity or alkalinity of a substance [118,119]. The acceptable range for pH in potable water typically falls between 6.5 and 8.5. The acceptable pH range for water suitable for irrigation purposes typically falls between 6 and 9. The variability in the pH level of effluent has the potential to impact the kinetics of biological reactions and the viability of diverse microorganisms. The variation of the pH values with temperature is shown in Figure 4. The initial pH of the wastewater prior to filtration was measured to be 7.62. The pH values observed in the study exhibited a maximum range of 7.14, 7.13, and 7.11, while the minimum range of pH was observed to be 7.06, 7.05, and 7.04.

3.2. Dissolved Oxygen (DO)

The graphical representation in Figure 4 illustrates the variation of Dissolved Oxygen (DO) with temperature. It is noteworthy that the highest DO levels were predominantly observed in the 3rd chamber, indicating a notable presence of oxygen in this particular section. However, it is worth mentioning that there was an exception, where one sample exhibited higher DO levels in the 1st chamber. The highest recorded DO value reached an impressive 4.57 mg/L, while the lowest observed DO level was 0.45 mg/L in the 3rd chamber. These DO values play a crucial role in assessing water quality as they serve as excellent indicators. It's important to note that the solubility of oxygen in wastewater is generally lower than that in clean water, making DO analysis a vital component of water pollution control and wastewater management. The significance of monitoring DO levels lies in its direct impact on aquatic ecosystems [120]. DO is a critical factor influencing various biochemical processes and metabolic activities of microorganisms, and its effects have been well-documented. The presence of adequate DO is essential for sustaining a diverse range of aquatic life forms, and the impact of water discharge into aquatic bodies is significantly determined by the oxygen balance within the system [121]. It's worth noting that the standard DO range typically falls between 4.5 and 8 mg/L, providing a benchmark for evaluating the water's oxygen content and, consequently, its overall health and suitability for various forms of life.

3.3. Nitrate Nitrogen (NO3-N)

In the analyzed wastewater samples, the nitrate concentration was found to be relatively low, well within the standard value of 10 mg/L. Notably, there was a consistent trend where nitrate values in the 3rd chamber were observed to be higher than those in the 2nd chamber for most of the samples. To provide a comprehensive view of the nitrate content with respect to temperature variations, Figure 5 illustrates the relationship between nitrate levels and temperature. Intriguingly, it was observed that as the temperature increased, the values of NO3-N exhibited an upward trend in the 2nd chamber. However, this pattern did not hold true for the 3rd chamber, where the values of NO3-N did not show a consistent increase with rising temperatures. Additionally, it's noteworthy that NO3-N values varied for the 3rd chamber at different temperature conditions.
The terminology "nitrate nitrogen" is used to specifically denote the nitrogen that is chemically bound within the nitrate ion. This specific nomenclature is employed to distinguish nitrate nitrogen from other forms of nitrogen, such as ammonia nitrogen or nitrite nitrogen. The analysis of nitrate nitrogen was conducted using the Hach DR2700 machine, with Nitraver 5 serving as the designated Nitrate reagent. This specialized testing equipment and reagent play a crucial role in accurately assessing nitrate nitrogen levels within the samples, providing valuable insights into the quality and composition of the wastewater under examination.

3.4. Total Suspended Solid (TSS)

Total Suspended Solids (TSS) is a critical water quality parameter that represents the dry weight of particles captured by a filter and is commonly used to evaluate the quality of wastewater [122]. In typical residential septic tank effluent, one can expect to find approximately 80 mg/L of TSS, a substantial portion of which comprises slowly biodegradable particles. However, the experimental findings in this study revealed an interesting relationship between TSS and temperature. It was observed that TSS levels increased as the temperature rose, and notably, the 2nd chamber consistently contained higher TSS concentrations compared to the 3rd chamber. To provide a more comprehensive perspective on this relationship, Figure 6 visually represents the variation of TSS in correlation with temperature. This graphical representation clearly indicates a direct connection between increasing temperature and higher TSS levels, with the 2nd chamber consistently exhibiting greater TSS values than the 3rd chamber.
It is worth noting that the study revealed some nuances in this pattern. In the 2nd chamber, TSS levels significantly increased with rising temperatures during the initial three sampling periods, only to experience a rapid decrease afterward. In contrast, the 3rd chamber exhibited more fluctuation in TSS concentrations as the temperature increased. These intriguing findings shed light on the intricate dynamics of TSS within the septic tank system and offer valuable insights into its behavior under varying temperature conditions.

3.5. Electric Conductivity (EC)

In the course of our study, we observed substantial variations in Electrical Conductivity (EC) values between the samples obtained from the 2nd chamber and the 3rd chamber of the septic tank. The EC values for the 2nd chamber were consistently higher, with measurements of 10200, 9800, 9400, 10050, and 9500 mS/cm. In stark contrast, the 3rd chamber exhibited significantly lower EC values, with measurements of 2300, 1200, 897, 1140, and 1150 mS/cm, respectively. This remarkable contrast in EC values between the two chambers is indicative of the septic tank's efficiency in the treatment process. The disparity in EC values underscores the dynamic nature of the septic tank's functionality. While the 2nd chamber seems to exhibit a higher electrical conductivity, it is vital to recognize that this may be attributed to the presence of various solutes and dissolved ions within the wastewater. As the wastewater undergoes treatment and moves through the septic tank's chambers, these solutes and ions are either transformed or removed, which could explain the noticeable drop in EC values in the 3rd chamber. These findings emphasize the capacity of the septic tank to effectively alter the composition of the wastewater as it progresses through its chambers. It also highlights the significance of EC as an indicator of the treatment efficiency, offering valuable insights into the changes that occur during the treatment process and how these changes affect the overall quality and composition of the effluent [123]. Understanding these dynamics is pivotal in assessing the septic tank's performance and its role in ensuring the safe and responsible disposal of wastewater.

4. Conclusion

This study has yielded several significant findings in relation to the wastewater characteristics of the septic tank. These findings are summarized as follows:
The examination of pH levels revealed variations, with the maximum recorded pH values spanning 7.14, 7.13, and 7.11, while the minimum pH levels were registered at 7.06, 7.05, and 7.09 for both of the selected chambers.
In light of the results, it is evident that the 2nd chamber consistently exhibited higher Total Suspended Solids (TSS) removal efficiency when compared to the 3rd chamber, particularly in response to temperature variations.
Lastly, the investigation highlighted a noteworthy trend in the organic removal efficiency of the septic tank, demonstrating a direct correlation with rising temperatures. Specifically, the organic removal efficiency showcased higher values during the summer season as opposed to the winter season. These findings collectively shed light on the dynamic nature of wastewater characteristics within septic tank systems, offering valuable insights into their behavior under varying environmental conditions.

References

  1. Anwar, S.; Nasrullah, M.; Hosen, M.J. COVID-19 and Bangladesh: Challenges and How to Address Them. Frontiers in Public Health 2020, 8. [Google Scholar] [CrossRef] [PubMed]
  2. Naher, N.; Balabanova, D.; Hutchinson, E.; Marten, R.; Hoque, R.; Tune, S.N.B.K.; Islam, B.Z.; Ahmed, S.M. Do Social Accountability Approaches Work? A Review of the Literature from Selected Low- and Middle-Income Countries in the WHO South-East Asia Region. Health Policy and Planning 2020, 35, i76–i96. [Google Scholar] [CrossRef] [PubMed]
  3. Cavoli, T.; Gopalan, S.; Onur, I.; Xenarios, S. Does Financial Inclusion Improve Sanitation Access? Empirical Evidence from Low- and Middle-Income Countries. International Journal of Water Resources Development 2023, 39, 724–745. [Google Scholar] [CrossRef]
  4. Foster, T.; Furey, S.; Banks, B.; Willetts, J. Functionality of Handpump Water Supplies: A Review of Data from Sub-Saharan Africa and the Asia-Pacific Region. International Journal of Water Resources Development 2020, 36, 855–869. [Google Scholar] [CrossRef]
  5. Sakamoto, M.; Begum, S.; Ahmed, T. Vulnerabilities to COVID-19 in Bangladesh and a Reconsideration of Sustainable Development Goals. Sustainability 2020, 12, 5296. [Google Scholar] [CrossRef]
  6. Organization, W.H. Health in 2015: From MDGs, Millennium Development Goals to SDGs, Sustainable Development Goals. 2015.
  7. millénaire, P.O. du; Binagwaho, A.; Sachs, J.D. Investing in Development: A Practical Plan to Achieve the Millennium Development Goals; Earthscan; Millennium Project, 2005; ISBN 1-84407-217-7.
  8. Pogge, T.; Sengupta, M. The Sustainable Development Goals: A Plan for Building a Better World? Journal of Global ethics 2015, 11, 56–64. [Google Scholar] [CrossRef]
  9. Chaukura, N.; Marais, S.S.; Moyo, W.; Mbali, N.; Thakalekoala, L.C.; Ingwani, T.; Mamba, B.B.; Jarvis, P.; Nkambule, T.T.I. Contemporary Issues on the Occurrence and Removal of Disinfection Byproducts in Drinking Water - A Review. Journal of Environmental Chemical Engineering 2020, 8, 103659. [Google Scholar] [CrossRef]
  10. Prihandrijanti, M.; Firdayati, M. Current Situation and Considerations of Domestic Waste-Water Treatment Systems for Big Cities in Indonesia (Case Study: Surabaya and Bandung). J Water Sustain 2011, 1, 97–104. [Google Scholar]
  11. Koottatep, T.; Pussayanavin, T.; Polprasert, C. Nouveau Design Solar Septic Tank: Reinvented Toilet Technology for Sanitation 4.0. Environmental Technology & Innovation 2020, 19, 100933. [Google Scholar]
  12. Verma, M.; Verma, M.K.; Singh, V.; Singh, J.; Singh, V.; Mishra, V. Advancements in Applicability of Microbial Fuel Cell for Energy Recovery from Human Waste. Bioresource Technology Reports 2022, 17, 100978. [Google Scholar] [CrossRef]
  13. Aravena, R.; Evans, M.L.; Cherry, J.A. Stable Isotopes of Oxygen and Nitrogen in Source Identification of Nitrate from Septic Systems. Groundwater 1993, 31, 180–186. [Google Scholar] [CrossRef]
  14. Swartz, C.H.; Reddy, S.; Benotti, M.J.; Yin, H.; Barber, L.B.; Brownawell, B.J.; Rudel, R.A. Steroid Estrogens, Nonylphenol Ethoxylate Metabolites, and Other Wastewater Contaminants in Groundwater Affected by a Residential Septic System on Cape Cod, MA. Environmental science & technology 2006, 40, 4894–4902. [Google Scholar]
  15. Viraraghavan, T. Influence of Temperature on the Performance of Septic Tank Systems. Water, Air, and Soil Pollution 1977, 7, 103–110. [Google Scholar] [CrossRef]
  16. Beal, C.D.; Gardner, E.A.; Menzies, N.W. Process, Performance, and Pollution Potential: A Review of Septic Tank–Soil Absorption Systems. Soil Research 2005, 43, 781–802. [Google Scholar] [CrossRef]
  17. Forsyth, K.A. Improving the Performance of Septic Tank Soil Absorption Systems: A Thesis Presented in Partial Fulfilment of the Requirements for the Degree of Master of Technology at Massey University. 1996.
  18. Viraraghavan, T. Temperature Effects on Onsite Wastewater Treatment and Disposal Systems. Journal of Environmental Health 1985, 10–13. [Google Scholar]
  19. Bradley, B.A. The Effects of Home Water Softener Regeneration Wastes on Septic Tank System Performance, Texas Tech University, 1981.
  20. Hickey, J.L.; Duncan, D.L. Performance of Single Family Septic Tank Systems in Alaska. Journal (Water Pollution Control Federation) 1966, 1298–1309. 1309.
  21. Roy, P.; Ahmed, M.A.; Islam, Md.S.; Azad, Md.A.K.; Islam, Md.S.; Islam, Md.R. Water Supply, Sanitation System and Water-Borne Diseases of Slum Dwellers of Bastuhara Colony, Khulna.; Department of Civil Engg., KUET: Khulna, Bangladesh, February 8 2020. [Google Scholar]
  22. Roy, P.; Ahmed, M.A.; Kumer, A. AN OVERVIEW OF HYGIENE PRACTICES AND HEALTH RISKS RELATED TO STREET FOODS AND DRINKING WATER FROM ROADSIDE RESTAURANTS OF KHULNA CITY OF BANGLADESH. EJERE 2019, 3, 47–55. [Google Scholar]
  23. Hu, Y.; Cheng, H.; Tao, S. Environmental and Human Health Challenges of Industrial Livestock and Poultry Farming in China and Their Mitigation. Environment international 2017, 107, 111–130. [Google Scholar] [CrossRef] [PubMed]
  24. Odey, E.A.; Li, Z.; Zhou, X.; Kalakodio, L. Fecal Sludge Management in Developing Urban Centers: A Review on the Collection, Treatment, and Composting. Environmental Science and Pollution Research 2017, 24, 23441–23452. [Google Scholar] [CrossRef]
  25. Ahmed, M.A.; Chakrabarti, S.D. SCENARIO OF EXISTING SOLID WASTE MANAGEMENT PRACTICES AND INTEGRATED SOLID WASTE MANAGEMENT MODEL FOR DEVELOPING COUNTRY WITH REFERENCE TO JHENAIDAH MUNICIPALITY, BANGLADESH.; Department of Civil Engg., KUET: Khulna, Bangladesh, February 8 2018. [Google Scholar]
  26. 26. Bahri, A.; Drechsel, P.; Brissaud, F. Water Reuse in Africa: Challenges and Opportunities. 2008.
  27. Chowdhary, P.; Bharagava, R.N.; Mishra, S.; Khan, N. Role of Industries in Water Scarcity and Its Adverse Effects on Environment and Human Health. Environmental Concerns and Sustainable Development: Volume 1: Air, Water and Energy Resources 2020, 235–256.
  28. Hasib, A.; Argha, D.B.P. COVID-19: LACK OF CORONAVIRUS WASTES MANAGEMENT-AN UPCOMING THREAT FOR THE MEGACITY DHAKA; 2021;
  29. Argha, D.B.P.; Hasib, A.; Rahman, M. A Comparative Study on the Variation of Air Quality Index of Dhaka City before and after the Nationwide Lockdown Due to COVID-19. In Proceedings of the 6th International Conference on Engineering Research, Bangladesh; 2021., Innovation and Education (2021). Sylhet. [Google Scholar]
  30. Palaniappan, M.; Gleick, P.H.; Allen, L.; Cohen, M.J.; Christian-Smith, J.; Smith, C. Water Quality. The world’s water: the biennial report on freshwater resources 2011, 45–72.
  31. Connor, R. The United Nations World Water Development Report 2015: Water for a Sustainable World; UNESCO publishing, 2015; Vol. 1; ISBN 92-3-100071-3.
  32. Gambhir, R.S.; Kapoor, V.; Nirola, A.; Sohi, R.; Bansal, V. Water Pollution: Impact of Pollutants and New Promising Techniques in Purification Process. Journal of Human Ecology 2012, 37, 103–109. [Google Scholar] [CrossRef]
  33. Rodriguez, E.; Sultan, R.; Hilliker, A. Negative Effects of Agriculture on Our Environment. The Traprock 2004, 3, 28–32. [Google Scholar]
  34. Ahmed, M.A.; Moniruzzaman, S.M. A STUDY ON PLASTIC WASTE RECYCLING PROCESS IN KHULNA CITY.; Department of Civil Engg., KUET: Khulna, Bangladesh, February 8 2018. [Google Scholar]
  35. Ahmed, Md.A.; Hossain, M.; Islam, M. Prediction of Solid Waste Generation Rate and Determination of Future Waste Characteristics at South-Western Region of Bangladesh Using Artificial Neural Network; WasteSafe 2017, KUET, Khulna, Bangladesh: KUET, Khulna, Bangladesh, 2017. [Google Scholar]
  36. Rahman, Md.M.; Argha, D.B.P.; Haque, M. PRESENT SCENARIO OF MUNICIPAL SOLID WASTE MANAGEMENT IN SATKHIRA MUNICIPALITY; 2018;
  37. Rashid, M.R.; Ashik, M. Evaluation of Physicochemical Treatment Technologies for Landfill Leachate Induced Dissolved Organic Nitrogen (DON). AEESP Research and Education Conference, Northeastern University, June 20-23, 2023 2023. 20 June.
  38. Ahmed*, M.A.; Redowan, M. Fate and Transport of the Biologically Treated Landfill Leachate Induced Dissolved Organic Nitrogen (DON). AEESP Research and Education Conference, Northeastern University, June 20-23, 2023 2023. 20 June.
  39. Roy, K.; Bari, Q.; Mostakim, S.; Argha, D.B.P. Water Supply History of Khulna City; 2019;
  40. Ritter, K.S. Sources, Pathways, and Relative Risks of Contaminants in Surface Water and Groundwater: A Perspective Prepared for the Walkerton Inquiry. Journal of Toxicology and Environmental Health Part A 2002, 65, 1–142. [Google Scholar]
  41. Azharul Haq, K. Water Management in Dhaka. Water Resources Development 2006, 22, 291–311. [Google Scholar] [CrossRef]
  42. Yongabi, K.A. Biocoagulants for Water and Waste Water Purification: A Review. International review of chemical engineering 2010, 2, 444–458. [Google Scholar]
  43. Yohannes, H.; Elias, E. Contamination of Rivers and Water Reservoirs in and around Addis Ababa City and Actions to Combat It. Environ Pollut Climate Change 2017, 1, 8. [Google Scholar] [CrossRef]
  44. Gray, N.F. Biology of Wastewater Treatment; World Scientific, 2004; Vol. 4; ISBN 1-78326-118-8.
  45. Cairncross, S.; Feachem, R. Environmental Health Engineering in the Tropics: Water, Sanitation and Disease Control; Routledge, 2018; ISBN 1-134-66586-5.
  46. Phonvisai, P.; Coowanitwong, N.; Shapkota, P.; Pradhan, P.; Hossain, M.M. Urban Wastewater and Sanitation Situation in Vientiane, Lao PDR. In Proceedings of the Proceedings: Regional Conference on Urban Water and Sanitation in Southeast Asian Cities; 2006; p. 221. [Google Scholar]
  47. Agboola, O.; Fayomi, O.S.I.; Ayodeji, A.; Ayeni, A.O.; Alagbe, E.E.; Sanni, S.E.; Okoro, E.E.; Moropeng, L.; Sadiku, R.; Kupolati, K.W.; et al. A Review on Polymer Nanocomposites and Their Effective Applications in Membranes and Adsorbents for Water Treatment and Gas Separation. Membranes 2021, 11, 139. [Google Scholar] [CrossRef] [PubMed]
  48. Ahmed, M.A.; Roy, P.; Shah, M.H.; Argha, D.P.; Datta, D.; Ri̇yad, R.H. Recycling of Cotton Dust for Organic Farming Is a Pivotal Replacement of Chemical Fertilizers by Composting and Its Quality Analysis. ERT 2021, 4, 108–116. [Google Scholar] [CrossRef]
  49. Ahmed, Md.A.; Roy, P.; Bari, A.; Azad, M. Conversion of Cow Dung to Biogas as Renewable Energy Through Mesophilic Anaerobic Digestion by Using Silica Gel as Catalyst; 5th ed.; ICMERE 2019, Chittagong University of Engineering & Technology (CUET): Chittagong, 2019; Ahmed, Md.A.; Roy, P.; Bari, A.; Azad, M. Conversion of Cow Dung to Biogas as Renewable Energy Through Mesophilic Anaerobic Digestion by Using Silica Gel as Catalyst; 5th, *!!! REPLACE !!!* (Eds.) C: ICMERE 2019, Chittagong University of Engineering & Technology (CUET).
  50. Roy, P.; Ahmed, Md.A.; Shah, Md.H. Biogas Generation from Kitchen and Vegetable Waste in Replacement of Traditional Method and Its Future Forecasting by Using ARIMA Model. Waste Dispos. Sustain. Energy 2021, 3, 165–175. [Google Scholar] [CrossRef]
  51. Khan, T.; Argha, D.B.P.; Anita, M.S. An Analysis of Existing Medical Waste Management and Possible Health Hazards in Jhenaidah Municipality; 2021;
  52. Ahmed, M.A.; Moniruzzaman, S.M. A STUDY ON PLASTIC WASTE RECYCLING PROCESS IN KHULNA CITY; 2018; 2018.
  53. Abdulhameed, I.M.; Sulaiman, S.O.; Najm, A.B.A. Reuse Wastewater By Using Water Evaluation And Planning (WEAP) (Ramadi City–Case Study). IOP Conf. Ser.: Earth Environ. Sci. 2021, 779, 012104. [Google Scholar] [CrossRef]
  54. Kumar, A.; Bisht, B.S.; Joshi, V.D.; Singh, A.K.; Talwar, A. Physical, Chemical and Bacteriological Study of Water from Rivers of Uttarakhand. Journal of Human Ecology 2010, 32, 169–173. [Google Scholar] [CrossRef]
  55. Topare, N.S.; Attar, S.J.; Manfe, M.M. Sewage/Wastewater Treatment Technologies: A Review. Sci. Revs. Chem. Commun 2011, 1, 18–24. [Google Scholar]
  56. Cantonati, M.; Poikane, S.; Pringle, C.M.; Stevens, L.E.; Turak, E.; Heino, J.; Richardson, J.S.; Bolpagni, R.; Borrini, A.; Cid, N.; et al. Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation. Water 2020, 12, 260. [Google Scholar] [CrossRef]
  57. Bogardi, J.J.; Leentvaar, J.; Sebesvári, Z. Biologia Futura: Integrating Freshwater Ecosystem Health in Water Resources Management. BIOLOGIA FUTURA 2020, 71, 337–358. [Google Scholar] [CrossRef]
  58. Schwarzenbach, R.P.; Egli, T.; Hofstetter, T.B.; von Gunten, U.; Wehrli, B. Global Water Pollution and Human Health. Annual Review of Environment and Resources 2010, 35, 109–136. [Google Scholar] [CrossRef]
  59. de Souza Machado, A.A.; Kloas, W.; Zarfl, C.; Hempel, S.; Rillig, M.C. Microplastics as an Emerging Threat to Terrestrial Ecosystems. Global Change Biology 2018, 24, 1405–1416. [Google Scholar] [CrossRef]
  60. Sherman, K. Toward Ecosystem-Based Management (EBM) of the World׳s Large Marine Ecosystems during Climate Change. Environmental Development 2014, 11, 43–66. [Google Scholar] [CrossRef]
  61. Mycoo, M. Sustainable Tourism, Climate Change and Sea Level Rise Adaptation Policies in Barbados. Natural Resources Forum 2014, 38, 47–57. [Google Scholar] [CrossRef]
  62. Dhyani, S.; Lahoti, S.; Khare, S.; Pujari, P.; Verma, P. Ecosystem Based Disaster Risk Reduction Approaches (EbDRR) as a Prerequisite for Inclusive Urban Transformation of Nagpur City, India. International Journal of Disaster Risk Reduction 2018, 32, 95–105. [Google Scholar] [CrossRef]
  63. Magel, C.L.; Francis, T.B. Evaluating Ecosystem-Based Management Alternatives for the Puget Sound, U.S.A. Social-Ecological System Using Qualitative Watershed Models. Frontiers in Marine Science 2022, 9. [Google Scholar] [CrossRef]
  64. Srinivasa Rao, Ch.; Kareemulla, K.; Krishnan, P.; Murthy, G.R.K.; Ramesh, P.; Ananthan, P.S.; Joshi, P.K. Agro-Ecosystem Based Sustainability Indicators for Climate Resilient Agriculture in India: A Conceptual Framework. Ecological Indicators 2019, 105, 621–633. [Google Scholar] [CrossRef]
  65. O’Boyle, R.; Jamieson, G. Observations on the Implementation of Ecosystem-Based Management: Experiences on Canada’s East and West Coasts. Fisheries Research 2006, 79, 1–12. [Google Scholar] [CrossRef]
  66. Curtin, R.; Prellezo, R. Understanding Marine Ecosystem Based Management: A Literature Review. Marine Policy 2010, 34, 821–830. [Google Scholar] [CrossRef]
  67. Saha, S.; Ahme, Md.R.; Ahmed, Md.A.; Islam, Md.S. Study on Rainwater Harvesting in Dacope Upazila, Khulna, Bangladesh.; Department of Civil Engg., CUET: Chittagong, Bangladesh, December 20 2018. [Google Scholar]
  68. Arnscheidt, J.; Jordan, P.; Li, S.; McCormick, S.; McFaul, R.; McGrogan, H.J.; Neal, M.; Sims, J.T. Defining the Sources of Low-Flow Phosphorus Transfers in Complex Catchments. Science of The Total Environment 2007, 382, 1–13. [Google Scholar] [CrossRef]
  69. Lopez-Ponnada, E.V.; Lynn, T.J.; Peterson, M.; Ergas, S.J.; Mihelcic, J.R. Application of Denitrifying Wood Chip Bioreactors for Management of Residential Non-Point Sources of Nitrogen. J Biol Eng 2017, 11, 16. [Google Scholar] [CrossRef] [PubMed]
  70. Deng, L.; Liu, Y.; Zheng, D.; Wang, L.; Pu, X.; Song, L.; Wang, Z.; Lei, Y.; Chen, Z.; Long, Y. Application and Development of Biogas Technology for the Treatment of Waste in China. Renewable and Sustainable Energy Reviews 2017, 70, 845–851. [Google Scholar] [CrossRef]
  71. Augustos de Lemos Chernicharo, C.; Von Sperling, M. Biological Wastewater Treatment in Warm Climate Regions; IWA Publishing, 2005; ISBN 978-1-78040-273-4.
  72. Dudley, B.; May, L. Estimating the Phosphorus Load to Waterbodies from Septic Tanks Available online:. Available online: https://nora.nerc.ac.uk/id/eprint/2531/ (accessed on 19 October 2023).
  73. Awaleh, M.; Soubaneh, Y. Waste Water Treatment in Chemical Industries: The Concept and Current Technologies. Hydrology Current Research 2014. [Google Scholar]
  74. Monroy, O.; Famá, G.; Meraz, M.; Montoya, L.; Macarie, H. Anaerobic Digestion for Wastewater Treatment in Mexico: State of the Technology. Water Research 2000, 34, 1803–1816. [Google Scholar] [CrossRef]
  75. Bugajski, P.; Chmielowski, K.; Kaczor, G. Optimizing the Percentage of Sewage from Septic Tanks for Stable Operation of a Wastewater Treatment Plant. Pol. J. Environ. Stud. 2016, 25, 1421–1425. [Google Scholar] [CrossRef] [PubMed]
  76. Bedinger, M.S. Site Characterization and Design of On-Site Septic Systems; ASTM International, 1997; ISBN 978-0-8031-2420-2.
  77. Moussavi, G.; Kazembeigi, F.; Farzadkia, M. Performance of a Pilot Scale Up-Flow Septic Tank for on-Site Decentralized Treatment of Residential Wastewater. Process Safety and Environmental Protection 2010, 88, 47–52. [Google Scholar] [CrossRef]
  78. Passeport, E.; Vidon, P.; Forshay, K.J.; Harris, L.; Kaushal, S.S.; Kellogg, D.Q.; Lazar, J.; Mayer, P.; Stander, E.K. Ecological Engineering Practices for the Reduction of Excess Nitrogen in Human-Influenced Landscapes: A Guide for Watershed Managers. Environmental Management 2013, 51, 392–413. [Google Scholar] [CrossRef] [PubMed]
  79. Kaid, M.; Ali, A.; Shamsan, A.; Younes, S.; Abdel-Raheem, S.; Abdul-Malik, M.; Salem, W. Efficiency of Maturation Oxidation Ponds as a Post-Treatment Technique of Wastewater. Current Chemistry Letters 2022, 11, 415–422. [Google Scholar] [CrossRef]
  80. Fernández del Castillo, A.; Verduzco Garibay, M.; Senés-Guerrero, C.; Yebra-Montes, C.; de Anda, J.; Gradilla-Hernández, M.S. Mathematical Modeling of a Domestic Wastewater Treatment System Combining a Septic Tank, an Up Flow Anaerobic Filter, and a Constructed Wetland. Water 2020, 12, 3019. [Google Scholar] [CrossRef]
  81. Biellik, R.J.; Henderson, P.L. The Performance of Aquaprivies in Thai Refugee Camps. Waterlines 1984, 3, 22–24. [Google Scholar] [CrossRef]
  82. Lossing, H.; Champagne, P.; McLellan, P.J. Examination of Sludge Accumulation Rates and Sludge Characteristics for a Decentralized Community Wastewater Treatment Systems with Individual Primary Clarifier Tanks Located in Wardsville (Ontario, Canada). Water Science and Technology 2010, 62, 2944–2952. [Google Scholar] [CrossRef]
  83. Noss, R.R.; Billa, M. Septic System Maintenance Management. Journal of Urban Planning and Development 1988, 114, 73–90. [Google Scholar] [CrossRef]
  84. Massoud, M.A.; Tarhini, A.; Nasr, J.A. Decentralized Approaches to Wastewater Treatment and Management: Applicability in Developing Countries. Journal of Environmental Management 2009, 90, 652–659. [Google Scholar] [CrossRef]
  85. Cotteral, J.A.; Norris, D.P. Septic Tank Systems. Journal of the Sanitary Engineering Division 1969, 95, 715–746. [Google Scholar] [CrossRef]
  86. Recirculating Aquaculture Tank Production Systems: Aquaponics—Integrating Fish and Plant Culture - Oklahoma State University Available online:. Available online: https://extension.okstate.edu/fact-sheets/recirculating-aquaculture-tank-production-systems-aquaponics-integrating-fish-and-plant-culture.html (accessed on 19 October 2023).
  87. Strande, L.; Brdjanovic, D. Faecal Sludge Management: Systems Approach for Implementation and Operation; IWA Publishing, 2014; ISBN 978-1-78040-472-1.
  88. Withers, P.J.; Jordan, P.; May, L.; Jarvie, H.P.; Deal, N.E. Do Septic Tank Systems Pose a Hidden Threat to Water Quality? Frontiers in Ecology and the Environment 2014, 12, 123–130. [Google Scholar] [CrossRef]
  89. Lusk, M.G.; Toor, G.S. Biodegradability and Molecular Composition of Dissolved Organic Nitrogen in Urban Stormwater Runoff and Outflow Water from a Stormwater Retention Pond. Environmental Science & Technology 2016, 50, 3391–3398. [Google Scholar]
  90. Arnade, L.J. Seasonal Correlation of Well Contamination and Septic Tank Distance. Groundwater 1999, 37, 920–923. [Google Scholar] [CrossRef]
  91. Smith, C.; Torrente-Murciano, L. The Potential of Green Ammonia for Agricultural and Economic Development in Sierra Leone. One earth 2021. [Google Scholar] [CrossRef]
  92. Schmidt, W.-P. The Elusive Effect of Water and Sanitation on the Global Burden of Disease. Tropical Medicine & International Health 2014. [Google Scholar] [CrossRef]
  93. Romanello, M.; McGushin, A.; Napoli, C.D.; Drummond, P.; Hughes, N.; Jamart, L.; Kennard, H.; Lampard, P.; Rodriguez, B.S.; Arnell, N.W.; et al. The 2021 Report of the Lancet Countdown on Health and Climate Change: Code Red for a Healthy Future. The Lancet 2021. [Google Scholar] [CrossRef]
  94. Wolf, J.; Prüss-Ustün, A.; Cumming, O.; Bartram, J.; Bonjour, S.; Cairncross, S.; Clasen, T.; Colford, J.M.; Curtis, V.; Fewtrell, L.; et al. Systematic Review: Assessing the Impact of Drinking Water and Sanitation on Diarrhoeal Disease in Low- and Middle-Income Settings: Systematic Review and Meta-Regression. Tropical Medicine & International Health 2014. [Google Scholar] [CrossRef]
  95. Prüss-Ustün, A.; Bartram, J.; Clasen, T.; Colford, J.M.; Cumming, O.; Curtis, V.; Bonjour, S.; Dangour, A.D.; Fewtrell, L.; Freeman, M.C.; et al. Burden of Disease from Inadequate Water, Sanitation and Hygiene in Low- and Middle-income Settings: A Retrospective Analysis of Data from 145 Countries. Tropical Medicine & International Health 2014. [Google Scholar] [CrossRef]
  96. Dawes, L.; Goonetilleke, A. An Investigation into the Role of Site and Soil Characteristics in Onsite Sewage Treatment. Env Geol 2003, 44, 467–477. [Google Scholar] [CrossRef]
  97. Li, P.; Karunanidhi, D.; Subramani, T.; Srinivasamoorthy, K. Sources and Consequences of Groundwater Contamination. Arch Environ Contam Toxicol 2021, 80, 1–10. [Google Scholar] [CrossRef]
  98. Jamieson, R.; Gordon, R.; Sharples, K.E.; Stratton, G.; Madani, A. Movement and Persistence of Fecal Bacteria in Agricultural Soils and Subsurface Drainage Water: A Review. Canadian Biosystems Engineering / Le Genie des biosystems au Canada 2002, 44, 1–1. [Google Scholar]
  99. Cleary, E.J.; Warner, D.L. Some Considerations in Underground Wastewater Disposal. Journal AWWA 1970, 62, 489–498. [Google Scholar] [CrossRef]
  100. Naidoo, S.; Olaniran, A.O. Treated Wastewater Effluent as a Source of Microbial Pollution of Surface Water Resources. International Journal of Environmental Research and Public Health 2014, 11, 249–270. [Google Scholar] [CrossRef]
  101. Angelakis, A.N.; Marecos Do Monte, M.H.F.; Bontoux, L.; Asano, T. The Status of Wastewater Reuse Practice in the Mediterranean Basin: Need for Guidelines. Water Research 1999, 33, 2201–2217. [Google Scholar] [CrossRef]
  102. Rasul, G.; Sharma, B. The Nexus Approach to Water–Energy–Food Security: An Option for Adaptation to Climate Change. Climate Policy 2016, 16, 682–702. [Google Scholar] [CrossRef]
  103. Bhaduri, A.; Ringler, C.; Dombrowski, I.; Mohtar, R.; Scheumann, W. Sustainability in the Water–Energy–Food Nexus. Water International 2015, 40, 723–732. [Google Scholar] [CrossRef]
  104. Md Khalid, R. REVIEW OF THE WATER SUPPLY MANAGEMENT AND REFORMS NEEDED TO ENSURE WATER SECURITY IN MALAYSIA. International Journal of Business and Society 2018, 19, 472–483. [Google Scholar]
  105. Farooq, R.; Ahmad, Z. Physico-Chemical Wastewater Treatment and Resource Recovery; BoD – Books on Demand, 2017; ISBN 978-953-51-3129-8.
  106. Mishra, B.K.; Kumar, P.; Saraswat, C.; Chakraborty, S.; Gautam, A. Water Security in a Changing Environment: Concept, Challenges and Solutions. Water 2021, 13, 490. [Google Scholar] [CrossRef]
  107. Cashman, A. Water Security and Services in the Caribbean. Water 2014, 6, 1187–1203. [Google Scholar] [CrossRef]
  108. Lusk, M.G.; Toor, G.S.; Yang, Y.-Y.; Mechtensimer, S.; De, M.; Obreza, T.A. A Review of the Fate and Transport of Nitrogen, Phosphorus, Pathogens, and Trace Organic Chemicals in Septic Systems. Critical Reviews in Environmental Science and Technology 2017, 47, 455–541. [Google Scholar] [CrossRef]
  109. Howe, C.W.; Linaweaver Jr., F. P. The Impact of Price on Residential Water Demand and Its Relation to System Design and Price Structure. Water Resources Research 1967, 3, 13–32. [Google Scholar] [CrossRef]
  110. Bajpai, P. Basics of Anaerobic Digestion Process. In Anaerobic Technology in Pulp and Paper Industry; Bajpai, P., Ed.; SpringerBriefs in Applied Sciences and Technology; Springer: Singapore, 2017; ISBN 978-981-10-4130-3. [Google Scholar]
  111. Andrews, J.F. Dynamic Model of the Anaerobic Digestion Process. Journal of the Sanitary Engineering Division 1969, 95, 95–116. [Google Scholar] [CrossRef]
  112. Merlin Christy, P.; Gopinath, L.R.; Divya, D. A Review on Anaerobic Decomposition and Enhancement of Biogas Production through Enzymes and Microorganisms. Renewable and Sustainable Energy Reviews 2014, 34, 167–173. [Google Scholar] [CrossRef]
  113. Rudel, R.A.; Melly, S.J.; Geno, P.W.; Sun, G.; Brody, J.G. Identification of Alkylphenols and Other Estrogenic Phenolic Compounds in Wastewater, Septage, and Groundwater on Cape Cod, Massachusetts. Environ. Sci. Technol. 1998, 32, 861–869. [Google Scholar] [CrossRef]
  114. Qasim, S.R. Wastewater Treatment Plants: Planning, Design, and Operation, Second Edition; Routledge, 2017; ISBN 978-1-351-40516-4.
  115. Teal, J.M.; Peterson, S.B. A Solar Aquatic System Septage Treatment Plant. Environ. Sci. Technol. 1993, 27, 34–37. [Google Scholar] [CrossRef]
  116. Mahon, J.M.; Knappe, J.; Gill, L.W. Sludge Accumulation Rates in Septic Tanks Used as Part of the On-Site Treatment of Domestic Wastewater in a Northern Maritime Temperate Climate. Journal of Environmental Management 2022, 304, 114199. [Google Scholar] [CrossRef] [PubMed]
  117. Peech, M. Hydrogen-Ion Activity. In Methods of Soil Analysis; John Wiley & Sons, Ltd, 1965; pp. 914–926 ISBN 978-0-89118-204-7.
  118. Krumbein, W.C.; Garrels, R.M. Origin and Classification of Chemical Sediments in Terms of pH and Oxidation-Reduction Potentials. The Journal of Geology 1952, 60, 1–33. [Google Scholar] [CrossRef]
  119. Dick, R.P.; Rasmussen, P.E.; Kerle, E.A. Influence of Long-Term Residue Management on Soil Enzyme Activities in Relation to Soil Chemical Properties of a Wheat-Fallow System. Biol Fert Soils 1988, 6, 159–164. [Google Scholar] [CrossRef]
  120. Baxa, M.; Musil, M.; Kummel, M.; Hanzlík, P.; Tesařová, B.; Pechar, L. Dissolved Oxygen Deficits in a Shallow Eutrophic Aquatic Ecosystem (Fishpond) – Sediment Oxygen Demand and Water Column Respiration Alternately Drive the Oxygen Regime. Science of The Total Environment 2021. [Google Scholar] [CrossRef]
  121. Vachon, D.; Sadro, S.; Bogard, M.J.; Lapierre, J.-F.; Baulch, H.M.; Rusak, J.A.; Denfeld, B.A.; Laas, A.; Klaus, M.; Karlsson, J.; et al. Paired O 2 –CO 2 Measurements Provide Emergent Insights into Aquatic Ecosystem Function. Limnology and oceanography letters 2020. [Google Scholar] [CrossRef]
  122. Guimarães, T.T.; Veronez, M.R.; Koste, E.C.; Souza, E.M.; Brum, D.; Gonzaga, L.; Mauad, F.F. Evaluation of Regression Analysis and Neural Networks to Predict Total Suspended Solids in Water Bodies from Unmanned Aerial Vehicle Images. Sustainability 2019, 11, 2580. [Google Scholar] [CrossRef]
  123. Desye, B.; Belete, B.; Asfaw Gebrezgi, Z.; Terefe Reda, T. Efficiency of Treatment Plant and Drinking Water Quality Assessment from Source to Household, Gondar City, Northwest Ethiopia. Journal of Environmental and Public Health 2021, 2021, e9974064. [Google Scholar] [CrossRef]
Preprints 88207 g001
Figure 1. Location of the selected septic tank at KUET campus.
Figure 1. Location of the selected septic tank at KUET campus.
Preprints 88207 g001
Preprints 88207 g002
Figure 2. The studied septic tank at KUET campus with three respective chambers.
Figure 2. The studied septic tank at KUET campus with three respective chambers.
Preprints 88207 g002
Preprints 88207 g003
Figure 3. The left side picture shows a 1st chamber of the septic tank and the middle picture shows the collection of wastewater from the 2nd chamber. Moreover, right side picture shows the sample of wastewater that was collected from the chamber of the septic tank.
Figure 3. The left side picture shows a 1st chamber of the septic tank and the middle picture shows the collection of wastewater from the 2nd chamber. Moreover, right side picture shows the sample of wastewater that was collected from the chamber of the septic tank.
Preprints 88207 g003
Preprints 88207 g004
Figure 4. the variation of pH and DO with Temperature. From the graph it can be said that with the increment of temperature, the values of pH and DO are also increasing and it is different for the two chambers (2nd and 3rd).
Figure 4. the variation of pH and DO with Temperature. From the graph it can be said that with the increment of temperature, the values of pH and DO are also increasing and it is different for the two chambers (2nd and 3rd).
Preprints 88207 g004
Preprints 88207 g005
Figure 5. Variation of NO3-N with Temperature.
Figure 5. Variation of NO3-N with Temperature.
Preprints 88207 g005
Preprints 88207 g006
Figure 6. Variation of TSS with the changes of temperature of different chamber.
Figure 6. Variation of TSS with the changes of temperature of different chamber.
Preprints 88207 g006
Table 1. Operational conditions required for the acceptable activity of methane-forming bacteria and subsequent methane production.
Table 1. Operational conditions required for the acceptable activity of methane-forming bacteria and subsequent methane production.
Parameters Operation Conditions Marginal
Alkalinity, mg/L as CaCO3 2000 1000-1500
Gas Composition Methane, % volume 67 60-65& 70-75
Carbon dioxide, % volume 32 25-30 & 35-40
Hydraulic retention time, days 13 7-10 & 15-30
pH 7.1 6.6-6.8 & 7.2-7.6
Temperature, Mesophillic 33°C 20-30° & 35-40°C
Temperature, Thermophillic 55°C 40-50° & 57-60°C
Volatile acids, mg/L as acetic acid 400 500-2000
Table 2. Septage characteristics of the septic tank.
Table 2. Septage characteristics of the septic tank.
Total Suspended Solids (TSS)
Biochemical Oxygen Demand
Chemical Oxygen Demand
Total Nitrogen as N (TN)
Total Phosphorus as P (TP)
Oil and Grease		 15200 mg/L
4820 mg/L
32500 mg/L
548 mg/L
230 mg/L
4500 mg/L
Table 3. Different Water Quality Parameters of Wastewater (2nd &3rd chamber) of the Septic Tank at KUET campus.
Table 3. Different Water Quality Parameters of Wastewater (2nd &3rd chamber) of the Septic Tank at KUET campus.
2nd chamber 3rd chamber
Date Temp
(ºC)		 pH DO
(mg/L)		 TSS
(mg/L)		 NO3-N
(mg/L)		 Temp
(ºC)		 pH DO
(mg/L)		 TSS
(mg/L)		 NO3-N
(mg/L)
26.12.20 18 - - 280 - 18 - - 110 -
05.02.21 21 7.05 1.18 1030 1.4 21.5 7.04 0.45 200 0.8
04.03.21 22 7.06 1.29 880 2 22 7.05 1.67 160 1.6
11.04.21 25.5 7.09 3.17 220 2.37 25.5 7.06 3.92 190 2.67
29.04.21 26 7.14 1.37 160 3.7 25 7.13 2.17 120 2
08.05.21 25.5 7.11 3.88 210 6.1 26 7.03 4.57 180 2.9
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.
Copyright: This open access article is published under a Creative Commons CC BY 4.0 license, which permit the free download, distribution, and reuse, provided that the author and preprint are cited in any reuse.
Prerpints.org logo

Preprints.org is a free preprint server supported by MDPI in Basel, Switzerland.

facebook logotwitter logolinkedin logo
MDPI Initiatives
Important Links
Subscribe

Disclaimer

Terms of Use

Privacy Policy

© 2024 MDPI (Basel, Switzerland) unless otherwise stated