The physical parameters were tested before and after all self-heating tests. The available data from the self-heating test is used to determine the biological stability of the compost. The results show that (i) a similar series of compostings with a similar initial waste mixture exhibits an almost similar area under temperature curve, i.e. the area is almost the same for forced and passive aerated composting. In another experiment (Exp-4) of this type, the areas are 10584°Ch and 10350°Ch for passively and forcefully aerated tanks, respectively. ii) Since the range of degradation and surface area under temperature curve is almost the same for both the processes, passive aerated composting in bins is recommended for batch purposes. 7 Change in total mass, moisture content, volatile solid, fixed solid in different self-heating tests.
Temperature variations during Exp-S, forced aerated bowl 33 Mass variation during Exp· I, passively aerated bowl 35 Mass variation during Exp-J, forced aerated bowl 35 Mass variation during Exp-4, passively aerated bowl 36 Mass variation during Exp-4 , forced aerated bowl 36 Temperature variations during self-heating test of RI 40 compost from both containers. Mass variation during self-heating test R I P Mass variation during self-heating test RI P Mass variation during self-heating test RI F Mass variation during self-healing test RI F Mass variation during self-heating test R4 P Mass variation during self-heating test test R4 P Mass variation during self-heating test R4 f.
General
Currently, research is of greater importance in the field of solid waste management to combat the organic part of solids. The end product of composting (aerobic decomposition) is known as compost, which can be usefully used as a soil improver, fertilizer or other purposes. The increasing rate of generation of solid waste from various sources causes environmental hazards. Stricter environmental regulations for new landfills and incinerators have introduced many new waste disposal techniques.
The large amount of organic waste (more than 70% of the total waste) can therefore be dumped directly in the landfill or can be broken down. On the other hand, as the degradable part of organic solid waste collected after composting, offers a short-term waste management.
INTROD UCTI ON CHAPTER ONE
To know the temperature variation in 11\'0 types of bin composting process namely forced aerated bin compost and passive aerated bin compost.
To determine the degree and extent of decomposition of compost produced after the first and second stages of composting. After World War II, agriculture became more mechanized and synthetic fertilizers began to reduce the use of manure and compost to improve soil fertility. In 1940 Sir Albert Howard published "An Agricultural Testament" which started the organic farming and gardening movement (VSAN RCC-1992). Today, organic landscaping and gardening methods are more popular than ever as farmers move away from harmful fertilizers and pesticides. With this growing movement, ironically, past methods involving the use of natural compost or manure to recondition the soil are making a comeback.
Over [he pnst two to three decades, lu.nnc::rs were not exclusively the ones to see the benefits of large-scale composting. Cities, towns and municipalities are becoming aware of the value or large-scale composting because of the disappearing space in landfills and the difficulty and cost associated with establishing new ones.
Histori cal Overv iew
Jean Baptiste Boussingault of France laid the foundations of agriculturul chemistry in 1834 by disproving the humus theory by demonstrating that plants obtain nourishment from certain chemicals in solution and not from the humus itself (V~AN.RCC-l 992).
Microorganisms
5 Composting is the process of converting bacteria or organic solid and semi-solid organic waste, sustainable solid transported without any negative environmental effects and can be used as organic fertilizer to improve or the quality and fertility of the soil. Composting is an ancient resource recovery process widely practiced in both the developing and industrialized parts of the world.
Composting process
- In-vessel system
- Silo
- Rot ating tu be
- Temperature
Aeration is achieved only through passive movement of air through perforated pipes embedded in the base layer of the pile. The duration depends on the type of material being composted and the frequency of rotations. Aeration is provided through the base of the silo so that air is forced up through the compost material.
TI1c length of Ilic bed and the turning frequency determine the duration of the composting process. The pH varies with time during the composting process and is a good indicator of the 2.6.6 pH. Then the digital pll meter (Model 3051, JENWAY) is used to determine the pH value of the compost directly.
A simplified approach to the analysis of the energy balance is based The composting process involves collecting and sorting solid waste in resource recovery. More than ten million people live in Dhaka. The city produces approximately 5,800 tons of solid waste every day, of which at least 80% is organic and suitable for composting (Comp.6). It will be very difficult to find locations to bury the waste as the city expands, and the transportation costs to transfer the waste will increase. In the participatory system, the waste generated in the home is stored in a bin, basket or bag and collected every day by a primary collector, who transports the waste to nearby transfer points by rickshwa van. The waste is then collected from the transfer points and taken to the final disposal point by a large truck. The city corporation has 60 Bigha of private land for dumping the solids. waste on the outskirts of Khulna town in Rajbandh. . In the conventional system, it is the responsibility of the householders to take their waste to the nearest waste bins or similar facilities provided by the city corporation and deposit waste there. The city corporation is responsible for transferring this waste from roadside containers to the final disposal site. In the city of Khulna, the main responsibility of the solid waste management system rests with the Khulna City Corporation. There are two methods of solid waste management in Khulna city area. The first is the collection and transportation of solid waste to the landfill, and the second is resource recovery and composting of solid waste. There are two types of collection and transportation of solid waste to landfill in Khulna City Corporation region. .. i) Conventional system ii) Participatory system. Khulna City Corporation produces approximately 455 tons of municipal solid waste per day considering all sources, and the production rate averages 0.5 kg/capita/day (Compi). The waste namely food, paper and sawdust was mixed in a selected ratio to have a suitable C/K ratio which ranged from 25 to 30 as suggested by Bari &. In Exp-2 and Exp-S, a kind of stage was composted and the mixed compost from both hin to Exp-I and Exp-l was used as raw material. Food waste was mixed with sawdust and waste paper (cut into small pieces) as shown in Figure 3.1. For most experiments, iwo bin, namely passively aerated bin and forced aerated bin are used. Source of waste The passively aerated composting bill was placed in an M.S frame, in order to facilitate the closure of the entire bin. A 2-inch diameter PVC pipe with holes was inserted into the side of the bin from top to bottom. The tube: was placed in the center of the bin which is considered as general practice. Figure: 3.4 Manually recorded temperature using digital thermometer. Temperature was monitored manually using a digital thermometer. Before and after each composting, waste and/or compost properties, such as moisture content, total solids, are swept away in two bins. Fresh compost released from different experiments from both reactor vessels transferred to some. The moisture content, volatile solids and solids of the matured compost were tested at the Environmental Engineering Laboratory of the Department of Civil Engineering, KUErl'. The biological stability of the produced compost can be determined using a self-heating test. In the passively aerated reactor, the temperature rose to a maximum of 50.2 °C and in most cases the temperature decreased several degrees after spin-up, as shown in Figure 4.1. In the forced aeration reactor the temperature rose to a maximum of 50.4 "C as shown in Figure 4.2, which is very close to each other. days. The area under the temperature curve, °Ch, is calculated by multiplying the generated biological heat in °C by the duration of the experiments. Temperature changes in the composting process of the containers were carried out with forced and passive ventilation. The rate and extent of decomposition to maturity of the compost was determined through the various stages of the composting process. In Exp-J, only a passively aerated reactor was used to know the ideal conditions for waste degradation. The compost released from both bins after the JO days was well mixed and used as raw material in Exp-2. Conclusions CONCLUSIONS AND RECOM1\.1ENDATIONS Recommendations for future studies BRAC (1997), Fertilizer recommendation Guide-1997 Bangladesh Agricultural Research Council, Soil Publication No.41. 1999) The effect of different aeration modes on solid waste composting in a closed system. Bari, Q.H, Koenig A and Tao G.H. (2000) Kinetic analysis of forced aeration composting-I. 2003) Current Status of Waste Containment in Bangladesh, Paper presented at the International Seminar and Workshops on Environmental Technology, April 2003, BlT.Khulna,_Bangladcsh. Parks, C.L. Atlas, M.R. Brown, E.A (1988) Laboratory Manual of Experimental Microbiology, A times Mirror Company, USA. 2004) A Study on Biochemical Quality of Kitchen Waste Compost in Bangladesh, Dhaka. A.(1991) Use of Oxygen as an Indicator of Compost Stability of Municipal Solid Waste: In Proceedings of the 7th International Conference on Solid Waste Management and Secondary Materials, Philadelphia, PA, USA. Vermont State Agency for Integrated Solid Waste Management of Natural Resources Center, McGraw Hill Publishing Company. Changes in total mass, moisture content and volatile solids, fixed solids during different Self-heating tests (last and final).
Use of compost
Preparation of waste mixture
CHA PTER THREE
Fabrication of two types of composting bin (Reactor)
Self -heating t est
RESULTS AND DISCUSSIONS CliAPTER FOUR
CHAPTER FIVE
RE FE RENC E
APPENDIX-A
