experimental study on the safe use of faecal sludge and
EXPERIMENTAL STUDY ON THE SAFE USE OF FAECAL SLUDGE AND ORGANIC SOLID WASTE THROUGH CO-COMPOSTING IN AQUACULTURE S. SAHA, M. ALAMGIR Department of Civil Engineering, Khulna University of Engineering & Technology, Khulna-9203, Bangladesh.
SUMMARY: This research work presents a combined treatment of faecal sludge (FS) and organic solid waste (OSW) through co-composting at three different mixing ratios such as 1:3, 1:3.5 and 1:4 with appropriate arrangements in windrow or heap type composting system about 45 days. It was conducted in KUET campus (waste management plant). Compost samples were taken for different tests and final product showed good result, usable in aquaculture. For aquaculture purposes, Tilapia fingerlings (Tilapia) and Channa punctate (Taki) fishes were experimented. From this research work, ratio 1:3 (FS: OSW) was better for aquaculture purpose. Finally, it can be concluded for using co-compost play a significant role in aquaculture sectors in Bangladesh.
1. INTRODUCTION Faecal sludge (FS) is the waste product collected from on-site sanitation systems, which in most cases remains untreated and is generally discharged into surrounding open spaces such as roads, drains and waterbodies. This unhygienic practice of faecal sludge management (FSM) creates an unhealthy living and environmental situation (Wash Bangladesh, 2016). Solutions for effective and sustainable faecal sludge management (FSM) presents a significant Global need (Strande et al., 2014). Most countries in the world experience challenges in managing waste. The importance of managing faecal sludge (FM) and municipal solid waste (MSW) has increased to avoid environmental degradation and public health risks. The lack of effective management of FM and MSW has been implicated in the transmission of many infectious diseases including cholera, typhoid and polio. Improving the situation of FSM is an urgent issue in all the rapidly growing countries like Bangladesh due to the absence of sewerage systems. In Bangladesh, the significance of improved FSM for ensuring sanitation is greatly acknowledged but it has not received adequate attention. Both central (National Sanitation Sector, WASH) and local authorities (WASA, Municipalities, City-Corporations) are struggling to solve it. Except for Dhaka, there is no formal or environmentally sound faecal sludge collection and disposal system in Bangladesh. Co-composting of faecal sludge and organic solid waste is the cost-effective solution. High
Proceedings Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium/ 2 - 6 October 2017 S. Margherita di Pula, Cagliari, Italy / © 2017 by CISA Publisher, Italy
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
temperatures attained in the composting process are effective in inactivating excreted pathogens contained in the FS and will convert both wastes into a hygienically safe compost. The two materials complement each other and provide good nutrients for fish. However, effective use of such compost in aquaculture depends among other factors on its quality. Quality is affected by the type of initial material, the process of composting and the maturity of the final product. After co-compost, it is usable in aquaculture. Bangladesh is considered as one of the most suitable region for aquaculture and fisheries in the world. The country has an inland water area of about 45,000 km2 and about 710 km long coastal belt. Fish is the second most valuable agricultural crop in Bangladesh and its production contributes to the livelihoods and employment of millions of people. The culture and consumption of fish therefore has important implications for national income and food security. Bangladeshi people are popularly referred to as "Mache Bhate Bangali" or "fish and rice makes a Bengali" (Ghose, 2014). Production of fish in ponds fertilised by faecal sludge is practiced in many countries in Asia, but it is not widespread in Bangladesh due to socio-cultural prejudices (Ahsan, 2014). However, FS contains high levels of valuable nutrients that could be used in many different ways in aquaculture. So, aquaculture can play a significant role in Bangladesh’s economy. The main objective of this research was to evaluate a proper co-composting mixing ratio of faecal sludge and organic solid waste that will produce a better quality of compost for aquaculture purposes. 1.1 General of co-composting Composting is the biological degradation of highly concentrated biodegradable organic wastes in the presence of oxygen (aerobically) to carbon dioxide and water, whereby the biologically generated waste heat is sufficient to raise the temperature of the composting mass to the thermophilic range (50 to 65 ºC) (Hafiz et al., 2017). Co-composting is the term used to indicate the composting of two different materials together. In this case faecal sludge and organic solid waste are composted together. Faecal sludge is relatively high in nitrogen content on the other hand solid waste is high in carbon content. Carbon is an energy source essential for cell growth and nitrogen is the major source for proteins needed by the microorganisms (Bari, 1999). Again both materials can be converted into a useful product. The rate of microbial activity or degradation in the composting mass depends on certain important physical and chemical factors such as particle size, C/N ratio, water content, temperature, pH and aeration. The final product of composting is a stable humus-like material known as compost (Bari, 1999). The decomposition of organic wastes in composting can be described by the following equation: Organic waste + O2 + Nutrients + Microorganisms Compost + CO2+ H2O+ NH3 +Heat (1)
2. METHODOLOGY 2.1 Study area This research work was conducted in Khulna University of Engineering & Technology (KUET). So, it can be said that the study area for this research work is KUET campus. KUET is situated in Khulna district, the third largest city in the southern area of Bangladesh. It lies between 22.9005° north latitude and between 89.5024° east longitudes. The co-composting
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
process and experimental study on co-compost was analysed at waste management plant (WMP) in KUET campus. The location of the study area is presented in Figure 1.
Figure 1. Location of solid waste management plant in KUET campus 2.2 Co-composting feedstock 2.2.1 Collection of Faecal Sludge At first, the permeability test of the drying bed samples was conducted by the constant head method for coarse grain soil. The size of the drying bed is 1250mmX1050mm and the maximum middle depth is 150mm. Before collecting the sample hand gloves and face mask were used in hand and mouth to ensure personal hygiene and safety. Normal buckets were used for the collection. Figure 2 shows the collection of faecal sludge from septic tank.
Figure 2. Collection of faecal sludge from septic tank
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2.2.2 Dewatering of faecal sludge The main purpose of a drying bed is to achieve physical separation between liquid and solids. After collection a bucket full of water it was immediately transferred to the drying bed. Disposed sludge was divided into two parts such as one was liquid part and the remaining part was solid. When the dewatering process was completed then only solid part was remaining in the drying bed. Gravel and sand layers were used for consisting layers of drying bed. At first, 75 mm gravel layer and 25 mm sand layer were laid over it. Then 50 mm layer of faecal sludge was applied (about 15 kg) and the dewatering process was continued for 15 days. Figure 3 shows throughing FS into drying bed. The sludge drying beds constitute a good option for obtaining dewatered or dried biosolids.
Figure 3. Throughing of faecal sludge into drying bed
2.2.3 Collection and Sorting of Solid Waste Solid waste was collected from the waste management plant of KUET campus at the same date of faecal sludge collection. This management plant collects wastes from the 7 residential halls and all the teachers and officer quarters daily basis. Co-compost quality greatly depends on sorting of waste that plays a vital role. Solid waste containing plastics and garbage waste that were sorted very carefully (Figure 4). Sorting is especially crucial with regard to hazardous waste.
Figure 4. Separation of non-biodegradable and biodegradable waste
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2.2.4 Faecal sludge and organic solid waste mixing ratio One of the objective of this research is to determine the proper mixing ratio of the faecal sludge and the organic solid waste that will produce the best quality of compost. In order to fulfill this objective the faecal sludge and organic solid waste was mixed at three different ratios. These ratios are 1:3, 1:3.5 and 1:4 (FS: OSW). This mixing (Figure 5) was done as weight proportion. Balancing of carbon and nitrogen is necessary for co-compost process. The ratio of carbon (C) to nitrogen (N) called C/N ratio which is very important for the biological conversion of the organic waste. The input material should have a C/N ratio preferably 25:1 to 40:1. It is evident that the faecal sludge is rich in nitrogen content due to the presence of urine and organic solid waste is rich in carbon content. The moisture content of the mixture is also a governing factor of the co-compost quality and small amount of water was added frequently.
Figure 5. During mixing of FS and OSW at three different ratios 2.2.5 Co-composting process Mixed wastes were transferred to the windrow or heap type compost heap. Three different mixing ratios were put into three different chamber of the compost heap. The compost heap helps to ensure the required temperature and air of the compost to reduce the harmful bacteria. The turning operation of the compost was done at every 7 days interval. This was done to maintain proper aeration throughout the composting mass. 2.2.6 Maturation Total composting operation continued about 45 days. During this time the compost mass turned into soil type color as shown in Figure 6. The absence of foul odor is also an indication of compost maturation. But the full maturation requires more days.
Figure 6. Final Product of Co-compost
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2.3 Experimental study on aquaculture Easily available and low-cost fishes (Tilapia fingerlings & Channa punctate) were used for aquaculture purposes. Three plastic container were used for conducting this work and it was conducted at the waste management plant of KUET campus. The radius of each drum was 30 cm and height of these drum was 45 cm. The capacity of each drum was stored water about 100 liters water. When the experiment was started, about 70-80 liters water were stored in each drum. This experiment was conducted with nursery reared Tilapia fingerlings as shown below Figure 7. This work designed to run for a period of 38th days. Some tests such as pH, DO, BOD5, Temperature, Total Coliform, Faecal Coliform were analysed at several days.
Figure 7. Experimental Study on Aquaculture
3. RESULTS AND DISCUSSION At first, tests for faecal sludge were carried by the two stages i.e. the initial stage and the final stage (after the dewatering process was completed). Then, some tests were carried out in two stages of the compost i.e. the initial stage and the final stage/finished compost. In every stage three different kinds of specimen/composts were tested. This research work was also done to determine the waste water quality which is a critical factor when culturing any aquatic organism and also determined the best mixing ratio of FS and OSW. 3.1 Physiochemical characteristics of faecal sludge after using drying bed Sludge drying beds are a secondary treatment for all kinds of sludge, including faecal sludge from on-site sanitation systems. Faecal sludge is hazardous but after the dewatering process its physical and chemical quality is better than initial condition. Table 1 shows that the comparison between before and after drying bed used. Table 1. Physiochemical Characteristics of Faecal Sludge Characteristics
Initial Faecal Sludge
Dewatered of FS after 15 days
pH Moisture (%) Carbon, C (%) Nitrogen, N (%)
8.1 93.74 25.37 0.6
7.7 16.50 12.56 0.70
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
C/N BOD5 (mg/L) COD (mg/L) Electrical Conductivity (Ms/cm) Fecal Coliform , FC (mpn/100 ml) Total Coliform, TC (mpn/100 ml)
42.28 981 6720 7.1 2200 3400
19.74 720 3960 6.4 1200 1800
3.2 Quality parameters of compost Physically there were no significant difference between three types of co-compost. The maximum temperature was occurred in the compost heap at 57º C. The living temperature of the pathogen is at 37º C and when the temperature is raised at 55º C in co-composting then most of the pathogens are stopped their workings. The concentration of different compost quality parameters of initial and finished conditions are presented in Table 2. In this research work no saw dust was used so that case C/N ratio was lower than standard limit. Table 2. Quality Parameters of three mixing ratios of FS and OSW Parameters pH Moisture Content (%) Volatile Solids (%) TOC* (%) TON* (%) C/N Ratio EC* (Ms/cm) FC* (mpn/100 ml) TC* (mpn/100 ml)
Before co-compost (FS: OSW) 1:3 1:3.5 1:4 5.73 5.86 6.20 48.21 50.67 54.04 50.20 57.98 63.17 27.89 32.21 35.09 1.45 1.27 1.18 19.23 25.36 29.74 8.26 7.69 7.50 500 400 400 2000 1800 1700
Finished Co-compost (FS: OSW) 1:3 1:3.5 1:4 7.65 7.91 8.05 16.50 19.71 24.20 22.67 26.64 31.01 12.59 14.80 17.23 2.63 2.29 2.18 4.79:1 6.46:1 7.90:1 11.4 12.5 8.09 100 60 40 600 440 400
(*TOC: Total Organic Carbon, TON: Total Organic Nitrogen EC: Electrical Conductivity, FC: Fecal Coliform, TC: Total Coliform)
3.3 Quality parameters of compost for aquaculture purposes This research work was to determine the water quality because water quality is a critical factor when culturing any aquatic organism. Optimal water quality varies by species and must be monitored to ensure growth and survival. Fish perform all their bodily functions in water. Because fish are totally dependent upon water to breathe, feed and grow, excrete wastes, maintain a salt balance, and reproduce, understanding the physical and chemical qualities of water is critical to successful aquaculture. Water quality parameters that are commonly monitored in aquaculture include temperature, dissolved oxygen, BOD5, pH, fecal coliform and total coliform. Water can hold large amounts of heat with a relatively small change in temperature. Dissolved oxygen (DO) is by far the most important chemical parameter in aquaculture. Lowdissolved oxygen levels are responsible for more fish kills, either directly or indirectly, than all other problems combined. Like humans, fish require oxygen for respiration. The amount of oxygen consumed by the fish is a function of its size, feeding rate, activity level, and temperature. Fish are not the only consumers of oxygen in aquaculture systems; bacteria, phytoplankton,
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
and zooplankton consume large quantities of oxygen as well. Decomposition of organic materials (bacteria and fish wastes) is the single greatest consumer of oxygen in aquaculture systems. The acceptable range for fish culture is normally between pH 6.5-9.0. Fresh water was used whose characteristics are given in Table 3. Table 3. Physiochemical Characteristics of fresh water Parameters
Value of fresh water
pH
7.61
Dissolved Oxygen (DO), (mg/L)
7.90
Biological Oxygen Demand (BOD5), (mg/L)
2.87
Temperature, (º C)
26.5
Hardness, (mg/L)
180
Fecal Coliform (FC), (mpn/100)
Nil
Total Coliform (TC), (mpn/100)
Nil
Table 4. Comparison of water quality parameters after using co-compost in aquaculture (Ratio 1:3)
Parameters pH DO* (mg/L) BOD5(mg/L) Temperature (º C) FC*(mpn/100) TC*(mpn/100)
Tilapia (Survival Days) Standard 1 13 Limit 7.67 6.86 6-8 7.54 2.58 3-10 2.04 Nil Not available 24.5 25.2 23.5-35 60 100 Not available 100 180 Not available
Taki ( Survival Days) 1
13
20
29
38
7.75 7.60 2.20
6.86 3.44 1.53
6.75 3.07 1.08
6.47 3.10 1.01
6.23 2.62 0.40
24.8 60
26.9 80
26.2 80
25.7 100
26.6 100
100
140
180
220
240
(*DO: Dissolved Oxygen, BOD: Biological Oxygen Demand, FC: Fecal Coliform, TC: Total Coliform)
Table 5. Comparison of water quality parameters after using co-compost in aquaculture (Ratio 1:3.5)
Parameters pH DO* (mg/L) BOD5(mg/L) Temperature (º C) FC*(mpn/100) TC*(mpn/100)
Tilapia (Survival Days) Standard 1 13 Limit 7.71 5.77 6-8 7.09 2.22 3-10 2.20 Nil Not available 25.8 26.7 23.5-35 Not 80 100 available 120 200 Not
Taki ( Survival Days) 1
13
20
29
38
7.80 7.70 2.35
7.83 5.20 1.97
7.50 4.03 1.26
6.98 3.20 1.01
6.23 0.32 Nil
25.4
25.8
26.5
25.7
25.8
40
60
80
80
100
80
120
160
200
240
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
available Table 6. Comparison of water quality parameters after using co-compost in aquaculture (Ratio 1:4)
Parameters pH DO* (mg/L) BOD5(mg/L) Temperature (º C) FC*(mpn/100) TC*(mpn/100)
Tilapia (Survival Days) Standard 1 13 Limit 7.85 6.12 6-8 7.18 2.34 3-10 1.95 Nil Not available 25.3 25.9 23.5-35 60 100 Not available 80 200 Not available
Taki ( Survival Days) 1
13
20
29
38
7.81 7.75 3.42
7.88 6.19 2.78
7.70 4.40 1.08
7.15 3.67 1.45
6.50 1.91 Nil
25.2 40
26.0 60
26.4 80
25.9 120
25.8 140
80
100
160
200
240
After 13-14th days, all fishes of Tilapia were died because of low amount of DO. DO was low because of Tilapia fishes were eaten less compost and that residue compost and small size of plastic drum was responsible to decrease the amount of DO. In other case, Taki fishes were alive until 38th days and their growth were also investigated by the weight basis. Table 7. Growth of Taki fish at different compost medium Ratio
Quantity of compost (gm)
Quantity of fish, Initial (gm)
1:3 1:3.5 1:4
100 100 100
115 100 95
Quantity of fish, Final (gm) (After 38th days) 135 80 (one fish died) 110
Due to plastic container the amount of DO was low gradually and in ratio of 1:3.5 sample, one fish was died because of low amount of DO but it didn’t have any trace of pathogenic bacteria.
Figure 8. Dead body of Taki fish due to lack of DO But the others two ratios of fishes were alive and growth of fish at ratio 1:3 is better than others two ratios. So, ratio 1:3 (FS:OSW) is better than others two ratios in aquaculture purposes.
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
4. CONCLUSIONS The following conclusions can be drawn from the research: • • • • •
The quality of finished co-compost are fairly good quality. For aquaculture purposes, ratio 1:3 (FS: OSW) is better than other two ratios. The amount of dissolved oxygen of waste water is decreased day-by-day and it is responsible for more fish kills. Survival time for Tilapia fish is less than Taki fish for the same source of water and different ratios of compost. Finally, it can be concluded that for using co-compost play a significant role in aquaculture sectors in Bangladesh.
AKNOWLEDGEMENTS The authors expresses their hearties thanks to Prof. Dr. Md. Nazmul Ahsan, Fisheries & Marine Resource Technology Discipline, Life Science School Khulna University, Khulna 9208; for his expert guidance, suggestion, co-operation and encouragement at every stage of work. The authors also likes to express their appreciation to Mr. Sarder Saidul Islam, Lab Assistant and Mr. Sayed Ahsan Ali, Assistant Technical Officer Environmental Engineering Lab, KUET. The authors also thanks to Mr. Md. Al Monsur and the staff of waste management plant, KUET, Khulna-9203.
REFERENCES
Ahsan M. N. (2014). Review of existing politics, laws and strategies for use of faecal sludge in aquaculture. SNV-FSM programme output, Dhaka, Bangladesh. Bari Q. H. (1999). Effect of different modes of aeration on composting of solid waste in a closed system. The HKU Scholars Hub, The University of Hong Kong. Ghose B. (2014). Fisheries and Aquaculture in Bangladesh: Challenges and Opportunities. Ann Aquac Res 1(1): 1001. Hafiz N. A. and Alamgir M. (2017). Faecal sludge management in kushtia municipality and cocomposting with organic solid waste, ISBN 978-984-34-2306-1. Strande, L., Ronteltap, M., Brdjanovic, D. (2014). Faecal Sludge Management, Systems Approach for Implementation and Operation. IWA Publishing. Wash Bangladesh (2016). Annual report on ”Impact of Treated Faecal Sludge on Fish Growth and Associated Health Risks.” SNV-FSM programme output, Bangladesh.
SUMMARY: This research work presents a combined treatment of faecal sludge (FS) and organic solid waste (OSW) through co-composting at three different mixing ratios such as 1:3, 1:3.5 and 1:4 with appropriate arrangements in windrow or heap type composting system about 45 days. It was conducted in KUET campus (waste management plant). Compost samples were taken for different tests and final product showed good result, usable in aquaculture. For aquaculture purposes, Tilapia fingerlings (Tilapia) and Channa punctate (Taki) fishes were experimented. From this research work, ratio 1:3 (FS: OSW) was better for aquaculture purpose. Finally, it can be concluded for using co-compost play a significant role in aquaculture sectors in Bangladesh.
1. INTRODUCTION Faecal sludge (FS) is the waste product collected from on-site sanitation systems, which in most cases remains untreated and is generally discharged into surrounding open spaces such as roads, drains and waterbodies. This unhygienic practice of faecal sludge management (FSM) creates an unhealthy living and environmental situation (Wash Bangladesh, 2016). Solutions for effective and sustainable faecal sludge management (FSM) presents a significant Global need (Strande et al., 2014). Most countries in the world experience challenges in managing waste. The importance of managing faecal sludge (FM) and municipal solid waste (MSW) has increased to avoid environmental degradation and public health risks. The lack of effective management of FM and MSW has been implicated in the transmission of many infectious diseases including cholera, typhoid and polio. Improving the situation of FSM is an urgent issue in all the rapidly growing countries like Bangladesh due to the absence of sewerage systems. In Bangladesh, the significance of improved FSM for ensuring sanitation is greatly acknowledged but it has not received adequate attention. Both central (National Sanitation Sector, WASH) and local authorities (WASA, Municipalities, City-Corporations) are struggling to solve it. Except for Dhaka, there is no formal or environmentally sound faecal sludge collection and disposal system in Bangladesh. Co-composting of faecal sludge and organic solid waste is the cost-effective solution. High
Proceedings Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium/ 2 - 6 October 2017 S. Margherita di Pula, Cagliari, Italy / © 2017 by CISA Publisher, Italy
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
temperatures attained in the composting process are effective in inactivating excreted pathogens contained in the FS and will convert both wastes into a hygienically safe compost. The two materials complement each other and provide good nutrients for fish. However, effective use of such compost in aquaculture depends among other factors on its quality. Quality is affected by the type of initial material, the process of composting and the maturity of the final product. After co-compost, it is usable in aquaculture. Bangladesh is considered as one of the most suitable region for aquaculture and fisheries in the world. The country has an inland water area of about 45,000 km2 and about 710 km long coastal belt. Fish is the second most valuable agricultural crop in Bangladesh and its production contributes to the livelihoods and employment of millions of people. The culture and consumption of fish therefore has important implications for national income and food security. Bangladeshi people are popularly referred to as "Mache Bhate Bangali" or "fish and rice makes a Bengali" (Ghose, 2014). Production of fish in ponds fertilised by faecal sludge is practiced in many countries in Asia, but it is not widespread in Bangladesh due to socio-cultural prejudices (Ahsan, 2014). However, FS contains high levels of valuable nutrients that could be used in many different ways in aquaculture. So, aquaculture can play a significant role in Bangladesh’s economy. The main objective of this research was to evaluate a proper co-composting mixing ratio of faecal sludge and organic solid waste that will produce a better quality of compost for aquaculture purposes. 1.1 General of co-composting Composting is the biological degradation of highly concentrated biodegradable organic wastes in the presence of oxygen (aerobically) to carbon dioxide and water, whereby the biologically generated waste heat is sufficient to raise the temperature of the composting mass to the thermophilic range (50 to 65 ºC) (Hafiz et al., 2017). Co-composting is the term used to indicate the composting of two different materials together. In this case faecal sludge and organic solid waste are composted together. Faecal sludge is relatively high in nitrogen content on the other hand solid waste is high in carbon content. Carbon is an energy source essential for cell growth and nitrogen is the major source for proteins needed by the microorganisms (Bari, 1999). Again both materials can be converted into a useful product. The rate of microbial activity or degradation in the composting mass depends on certain important physical and chemical factors such as particle size, C/N ratio, water content, temperature, pH and aeration. The final product of composting is a stable humus-like material known as compost (Bari, 1999). The decomposition of organic wastes in composting can be described by the following equation: Organic waste + O2 + Nutrients + Microorganisms Compost + CO2+ H2O+ NH3 +Heat (1)
2. METHODOLOGY 2.1 Study area This research work was conducted in Khulna University of Engineering & Technology (KUET). So, it can be said that the study area for this research work is KUET campus. KUET is situated in Khulna district, the third largest city in the southern area of Bangladesh. It lies between 22.9005° north latitude and between 89.5024° east longitudes. The co-composting
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
process and experimental study on co-compost was analysed at waste management plant (WMP) in KUET campus. The location of the study area is presented in Figure 1.
Figure 1. Location of solid waste management plant in KUET campus 2.2 Co-composting feedstock 2.2.1 Collection of Faecal Sludge At first, the permeability test of the drying bed samples was conducted by the constant head method for coarse grain soil. The size of the drying bed is 1250mmX1050mm and the maximum middle depth is 150mm. Before collecting the sample hand gloves and face mask were used in hand and mouth to ensure personal hygiene and safety. Normal buckets were used for the collection. Figure 2 shows the collection of faecal sludge from septic tank.
Figure 2. Collection of faecal sludge from septic tank
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2.2.2 Dewatering of faecal sludge The main purpose of a drying bed is to achieve physical separation between liquid and solids. After collection a bucket full of water it was immediately transferred to the drying bed. Disposed sludge was divided into two parts such as one was liquid part and the remaining part was solid. When the dewatering process was completed then only solid part was remaining in the drying bed. Gravel and sand layers were used for consisting layers of drying bed. At first, 75 mm gravel layer and 25 mm sand layer were laid over it. Then 50 mm layer of faecal sludge was applied (about 15 kg) and the dewatering process was continued for 15 days. Figure 3 shows throughing FS into drying bed. The sludge drying beds constitute a good option for obtaining dewatered or dried biosolids.
Figure 3. Throughing of faecal sludge into drying bed
2.2.3 Collection and Sorting of Solid Waste Solid waste was collected from the waste management plant of KUET campus at the same date of faecal sludge collection. This management plant collects wastes from the 7 residential halls and all the teachers and officer quarters daily basis. Co-compost quality greatly depends on sorting of waste that plays a vital role. Solid waste containing plastics and garbage waste that were sorted very carefully (Figure 4). Sorting is especially crucial with regard to hazardous waste.
Figure 4. Separation of non-biodegradable and biodegradable waste
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2.2.4 Faecal sludge and organic solid waste mixing ratio One of the objective of this research is to determine the proper mixing ratio of the faecal sludge and the organic solid waste that will produce the best quality of compost. In order to fulfill this objective the faecal sludge and organic solid waste was mixed at three different ratios. These ratios are 1:3, 1:3.5 and 1:4 (FS: OSW). This mixing (Figure 5) was done as weight proportion. Balancing of carbon and nitrogen is necessary for co-compost process. The ratio of carbon (C) to nitrogen (N) called C/N ratio which is very important for the biological conversion of the organic waste. The input material should have a C/N ratio preferably 25:1 to 40:1. It is evident that the faecal sludge is rich in nitrogen content due to the presence of urine and organic solid waste is rich in carbon content. The moisture content of the mixture is also a governing factor of the co-compost quality and small amount of water was added frequently.
Figure 5. During mixing of FS and OSW at three different ratios 2.2.5 Co-composting process Mixed wastes were transferred to the windrow or heap type compost heap. Three different mixing ratios were put into three different chamber of the compost heap. The compost heap helps to ensure the required temperature and air of the compost to reduce the harmful bacteria. The turning operation of the compost was done at every 7 days interval. This was done to maintain proper aeration throughout the composting mass. 2.2.6 Maturation Total composting operation continued about 45 days. During this time the compost mass turned into soil type color as shown in Figure 6. The absence of foul odor is also an indication of compost maturation. But the full maturation requires more days.
Figure 6. Final Product of Co-compost
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2.3 Experimental study on aquaculture Easily available and low-cost fishes (Tilapia fingerlings & Channa punctate) were used for aquaculture purposes. Three plastic container were used for conducting this work and it was conducted at the waste management plant of KUET campus. The radius of each drum was 30 cm and height of these drum was 45 cm. The capacity of each drum was stored water about 100 liters water. When the experiment was started, about 70-80 liters water were stored in each drum. This experiment was conducted with nursery reared Tilapia fingerlings as shown below Figure 7. This work designed to run for a period of 38th days. Some tests such as pH, DO, BOD5, Temperature, Total Coliform, Faecal Coliform were analysed at several days.
Figure 7. Experimental Study on Aquaculture
3. RESULTS AND DISCUSSION At first, tests for faecal sludge were carried by the two stages i.e. the initial stage and the final stage (after the dewatering process was completed). Then, some tests were carried out in two stages of the compost i.e. the initial stage and the final stage/finished compost. In every stage three different kinds of specimen/composts were tested. This research work was also done to determine the waste water quality which is a critical factor when culturing any aquatic organism and also determined the best mixing ratio of FS and OSW. 3.1 Physiochemical characteristics of faecal sludge after using drying bed Sludge drying beds are a secondary treatment for all kinds of sludge, including faecal sludge from on-site sanitation systems. Faecal sludge is hazardous but after the dewatering process its physical and chemical quality is better than initial condition. Table 1 shows that the comparison between before and after drying bed used. Table 1. Physiochemical Characteristics of Faecal Sludge Characteristics
Initial Faecal Sludge
Dewatered of FS after 15 days
pH Moisture (%) Carbon, C (%) Nitrogen, N (%)
8.1 93.74 25.37 0.6
7.7 16.50 12.56 0.70
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
C/N BOD5 (mg/L) COD (mg/L) Electrical Conductivity (Ms/cm) Fecal Coliform , FC (mpn/100 ml) Total Coliform, TC (mpn/100 ml)
42.28 981 6720 7.1 2200 3400
19.74 720 3960 6.4 1200 1800
3.2 Quality parameters of compost Physically there were no significant difference between three types of co-compost. The maximum temperature was occurred in the compost heap at 57º C. The living temperature of the pathogen is at 37º C and when the temperature is raised at 55º C in co-composting then most of the pathogens are stopped their workings. The concentration of different compost quality parameters of initial and finished conditions are presented in Table 2. In this research work no saw dust was used so that case C/N ratio was lower than standard limit. Table 2. Quality Parameters of three mixing ratios of FS and OSW Parameters pH Moisture Content (%) Volatile Solids (%) TOC* (%) TON* (%) C/N Ratio EC* (Ms/cm) FC* (mpn/100 ml) TC* (mpn/100 ml)
Before co-compost (FS: OSW) 1:3 1:3.5 1:4 5.73 5.86 6.20 48.21 50.67 54.04 50.20 57.98 63.17 27.89 32.21 35.09 1.45 1.27 1.18 19.23 25.36 29.74 8.26 7.69 7.50 500 400 400 2000 1800 1700
Finished Co-compost (FS: OSW) 1:3 1:3.5 1:4 7.65 7.91 8.05 16.50 19.71 24.20 22.67 26.64 31.01 12.59 14.80 17.23 2.63 2.29 2.18 4.79:1 6.46:1 7.90:1 11.4 12.5 8.09 100 60 40 600 440 400
(*TOC: Total Organic Carbon, TON: Total Organic Nitrogen EC: Electrical Conductivity, FC: Fecal Coliform, TC: Total Coliform)
3.3 Quality parameters of compost for aquaculture purposes This research work was to determine the water quality because water quality is a critical factor when culturing any aquatic organism. Optimal water quality varies by species and must be monitored to ensure growth and survival. Fish perform all their bodily functions in water. Because fish are totally dependent upon water to breathe, feed and grow, excrete wastes, maintain a salt balance, and reproduce, understanding the physical and chemical qualities of water is critical to successful aquaculture. Water quality parameters that are commonly monitored in aquaculture include temperature, dissolved oxygen, BOD5, pH, fecal coliform and total coliform. Water can hold large amounts of heat with a relatively small change in temperature. Dissolved oxygen (DO) is by far the most important chemical parameter in aquaculture. Lowdissolved oxygen levels are responsible for more fish kills, either directly or indirectly, than all other problems combined. Like humans, fish require oxygen for respiration. The amount of oxygen consumed by the fish is a function of its size, feeding rate, activity level, and temperature. Fish are not the only consumers of oxygen in aquaculture systems; bacteria, phytoplankton,
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
and zooplankton consume large quantities of oxygen as well. Decomposition of organic materials (bacteria and fish wastes) is the single greatest consumer of oxygen in aquaculture systems. The acceptable range for fish culture is normally between pH 6.5-9.0. Fresh water was used whose characteristics are given in Table 3. Table 3. Physiochemical Characteristics of fresh water Parameters
Value of fresh water
pH
7.61
Dissolved Oxygen (DO), (mg/L)
7.90
Biological Oxygen Demand (BOD5), (mg/L)
2.87
Temperature, (º C)
26.5
Hardness, (mg/L)
180
Fecal Coliform (FC), (mpn/100)
Nil
Total Coliform (TC), (mpn/100)
Nil
Table 4. Comparison of water quality parameters after using co-compost in aquaculture (Ratio 1:3)
Parameters pH DO* (mg/L) BOD5(mg/L) Temperature (º C) FC*(mpn/100) TC*(mpn/100)
Tilapia (Survival Days) Standard 1 13 Limit 7.67 6.86 6-8 7.54 2.58 3-10 2.04 Nil Not available 24.5 25.2 23.5-35 60 100 Not available 100 180 Not available
Taki ( Survival Days) 1
13
20
29
38
7.75 7.60 2.20
6.86 3.44 1.53
6.75 3.07 1.08
6.47 3.10 1.01
6.23 2.62 0.40
24.8 60
26.9 80
26.2 80
25.7 100
26.6 100
100
140
180
220
240
(*DO: Dissolved Oxygen, BOD: Biological Oxygen Demand, FC: Fecal Coliform, TC: Total Coliform)
Table 5. Comparison of water quality parameters after using co-compost in aquaculture (Ratio 1:3.5)
Parameters pH DO* (mg/L) BOD5(mg/L) Temperature (º C) FC*(mpn/100) TC*(mpn/100)
Tilapia (Survival Days) Standard 1 13 Limit 7.71 5.77 6-8 7.09 2.22 3-10 2.20 Nil Not available 25.8 26.7 23.5-35 Not 80 100 available 120 200 Not
Taki ( Survival Days) 1
13
20
29
38
7.80 7.70 2.35
7.83 5.20 1.97
7.50 4.03 1.26
6.98 3.20 1.01
6.23 0.32 Nil
25.4
25.8
26.5
25.7
25.8
40
60
80
80
100
80
120
160
200
240
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
available Table 6. Comparison of water quality parameters after using co-compost in aquaculture (Ratio 1:4)
Parameters pH DO* (mg/L) BOD5(mg/L) Temperature (º C) FC*(mpn/100) TC*(mpn/100)
Tilapia (Survival Days) Standard 1 13 Limit 7.85 6.12 6-8 7.18 2.34 3-10 1.95 Nil Not available 25.3 25.9 23.5-35 60 100 Not available 80 200 Not available
Taki ( Survival Days) 1
13
20
29
38
7.81 7.75 3.42
7.88 6.19 2.78
7.70 4.40 1.08
7.15 3.67 1.45
6.50 1.91 Nil
25.2 40
26.0 60
26.4 80
25.9 120
25.8 140
80
100
160
200
240
After 13-14th days, all fishes of Tilapia were died because of low amount of DO. DO was low because of Tilapia fishes were eaten less compost and that residue compost and small size of plastic drum was responsible to decrease the amount of DO. In other case, Taki fishes were alive until 38th days and their growth were also investigated by the weight basis. Table 7. Growth of Taki fish at different compost medium Ratio
Quantity of compost (gm)
Quantity of fish, Initial (gm)
1:3 1:3.5 1:4
100 100 100
115 100 95
Quantity of fish, Final (gm) (After 38th days) 135 80 (one fish died) 110
Due to plastic container the amount of DO was low gradually and in ratio of 1:3.5 sample, one fish was died because of low amount of DO but it didn’t have any trace of pathogenic bacteria.
Figure 8. Dead body of Taki fish due to lack of DO But the others two ratios of fishes were alive and growth of fish at ratio 1:3 is better than others two ratios. So, ratio 1:3 (FS:OSW) is better than others two ratios in aquaculture purposes.
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
4. CONCLUSIONS The following conclusions can be drawn from the research: • • • • •
The quality of finished co-compost are fairly good quality. For aquaculture purposes, ratio 1:3 (FS: OSW) is better than other two ratios. The amount of dissolved oxygen of waste water is decreased day-by-day and it is responsible for more fish kills. Survival time for Tilapia fish is less than Taki fish for the same source of water and different ratios of compost. Finally, it can be concluded that for using co-compost play a significant role in aquaculture sectors in Bangladesh.
AKNOWLEDGEMENTS The authors expresses their hearties thanks to Prof. Dr. Md. Nazmul Ahsan, Fisheries & Marine Resource Technology Discipline, Life Science School Khulna University, Khulna 9208; for his expert guidance, suggestion, co-operation and encouragement at every stage of work. The authors also likes to express their appreciation to Mr. Sarder Saidul Islam, Lab Assistant and Mr. Sayed Ahsan Ali, Assistant Technical Officer Environmental Engineering Lab, KUET. The authors also thanks to Mr. Md. Al Monsur and the staff of waste management plant, KUET, Khulna-9203.
REFERENCES
Ahsan M. N. (2014). Review of existing politics, laws and strategies for use of faecal sludge in aquaculture. SNV-FSM programme output, Dhaka, Bangladesh. Bari Q. H. (1999). Effect of different modes of aeration on composting of solid waste in a closed system. The HKU Scholars Hub, The University of Hong Kong. Ghose B. (2014). Fisheries and Aquaculture in Bangladesh: Challenges and Opportunities. Ann Aquac Res 1(1): 1001. Hafiz N. A. and Alamgir M. (2017). Faecal sludge management in kushtia municipality and cocomposting with organic solid waste, ISBN 978-984-34-2306-1. Strande, L., Ronteltap, M., Brdjanovic, D. (2014). Faecal Sludge Management, Systems Approach for Implementation and Operation. IWA Publishing. Wash Bangladesh (2016). Annual report on ”Impact of Treated Faecal Sludge on Fish Growth and Associated Health Risks.” SNV-FSM programme output, Bangladesh.
