The paper reports on the material flow analysis and integrated bio-systems of a practical Micro Treatment Plant Model (MTPM'2000) used for urban solid waste in Indian context. Earlier during 1994, seven optional technological sub-systems namely, vermi-composting, bacterial composting, sanitary refill, fuel pellets, boiler fuel, bio-gas/vermi-composting and mushroom growing have been listed for Environmental Sound Technology (EST) determinants for sustainable scales of operation. The conceptual model’94 was primarily based on operational treatment plants and their working parameters viz., minimum size of the unit, volume of garbage, holding time, useful mass throughput, quality of waste input, waste generated and infrastructure, labour and capital cost parameters viz., land area required, capital investment, labour employed, product/energy recovered and net returns per ton of solid waste processed etc.,.

Conceptual model'94 was developed under a bilateral development project supported and facilitated by the University of Amsterdam, The Netherlands and KSCST (Karnataka State Council for Science and Technology).respectively. The model was based on field research studies, during 1992-1994 in the cities of Bangalore, Hyderabad and Chennai, India. The study was taken up essentially to establish linkages between formal and informal sectors involving various stake holders. The author served as one of the steering committee member in the above bilateral project.. Practical micro treatment plants in the past have undergone significant design changes leading to optimizations and have expanded in numbers in both metropolitan and medium size urban settlements. The salient aspects of findings in 1994 studies are listed. Developments in the past six years in Composting as a case study are presented in this paper. The vital aspects of decentralized USWM are discussed SWM.

Selected technological determinants of main inputs and outputs in typical four subsystems in 1994 Model:

• Vermi-composting : min. size 1mX1mX0.3m: min.vol. of waste treated 0.3 cu.m/day : min.viable size 0.25 tons/day: useful mass throughput 0.25 by dry wt. : holding time 15+25 days, labour employed 2 mandays, value of product Rs,2000-5000 per ton
• Bacterial composting: min size 5mX4mX1.5m : min. volume of waste treated 30 cu.m/day, 0.3 useful mass throughput by dry weight: holding time 49 days: labour employed 10-15 mandays , value of product Rs.300-500 per ton.
• Fuel Pellets : one plant, min volume of waste treated 30-100 cu.m/day: holding time 3-7 days, energy recovered 1170 kcals/kg: value of product Rs.3000 per ton.
• Mushroom : min size 6mX2mX1.5m : min volume of waste treated 0.6 cu.m/day: holding time 30+21 days: labour 3 mandays: energy recovered 735 kcal/kg : value of product Rs.20,000 per ton.

The paper records an Environmental Sound Technology(EST) experimental community model MTPM'2000 with actual material flows and integration of various bio-systems. Enhancing ecological literacy for efficient material segregation at sources such as households, need based training of the waste handlers and supervisors in local authorities, optimizing material flows based on environmental sound technology are recommended. A network at local cities level for implementing the CBSWM using ESTs is recommended.

Keywords: 
Micro Treatment Plant Model (MTPM'2000), Aerobic Composting, Urban solid waste, UNEP-IETC maESTro, ESTs,Vermi-composting, Bacterial composting, USWM’94 Model 

1.0 INTRODUCTION 

Conventionally, the organic and inorganic materials which have lost their values in the eyes of the first owner are termed as solid waste. Where as, there is nothing like waste in nature- it is only a resource at wrong place. The Urban Solid Waste Management(USWM) growing exponentially has reached disastrous proportions in all large cities in India. The problem is critical further for reasons of lowered social, resource and techno-management initiatives and community participation. Coupled with budgetary restrictions, poorly motivated staff and sweepers, inadequate fleet of vehicles the solid waste is only one of the 10-12 responsibilities in the local authorities. The existing infrastructure is barely adequate to cope up with the today's need alone. 

The alternative scenario is with a premise that "garbage is a valuable commodity" if handled and rendered to a socially useful commodity. While the citizens in general are indifferent to this problem and expect the municipal authorities to tackle, there are examples of a few NGO's and CBOs who have been able to enlist citizens participation to successfully overcome the USW problem within small localities by engaging local rag pickers in a constructive manner. In this context alternative collection mechanisms, inventory of the conservation and disposal options are highly relevant needs. These options can also devise mechanisms which can integrate the existing structure and provide strong linkages with the community to ensure a socially and scientifically appropriate management strategies.

Further, Environmental Sound Technologies(ESTs) encompass technologies that have the potential for significantly improved environmental performance relative to other technologies. Broadly speaking, these technologies protect the environment, are less polluting,use resources in sustainable manner,recycle more of their wastes and products, and handle all residual wastes in a more environmentally acceptable way than the technologies for which they are substitutes(UNEP-IETC,1999). To be sustainable, ESTs should also be compatible with nationally determined soci-economic,cultural and environmental priorities and development goals. UNEP-IETC has come out with a data base MaESTro. It contains information on a full range of environmental sound technologies,institutions and information sources on solid waste, waste water, water augmentation and environmental management. maESTro is down loadable free of charge from IETCs web-site under the URL : http://www.unep.or.jp/ietc/ESTdir/maestro/setup2.html. The USWM’94 and MTP’2000 model are found reasonably relevant to ESTs and are discussed in this paper.
 

2.0 EXISTING URBAN SOLID WASTE COLLECTION SYSTEMS

It is general situation that household wastes are tipped haphazardly in and around the road side dustbins. Apart from the unaesthetic consideration of such a system, the major disadvantage is that the inadvertent mixing of various fractions of USW leave little scope for effective recovery of recyclable and removal and transport of problematic fermentables. In addition, the waste pickers who perform the useful task of removal of recyclable are vulnerable to hazards of injury and infection from broken glass and unsanitary components. (Photo:01) The two alternatives for the above is house to house collection and modified collection from roadside bins.
 
 

The relative occurrence of the three main fractions of garbage namely, the 1. Recyclable 2. Decomposable and 3. Non-decomposable and / or non combustibles decide the nature of garbage collected and technology options. In roadside bins, owing to the mix up of different constituents of USW and due to soil contamination all the potentially recyclable materials cannot be recovered. This could however, be overcome if USW is source segregated. The major constituent of domestic USW is the decomposable fraction in the range of 20-40 percent of the waste. The high moisture content of USW, as well as about a 24-hour residence time in domestic trash cans enhancing the incidence of partial aerobic decomposition and release of malodorous by-products, necessitates that the USW be cleared every day.

Management of municipal solid waste in India has reached a crucial stage after a number of Public Interest Litigation(PIL) in the Supreme Court on the lapses by the local authorities responsible for it. The Municipal Solid Wastes(Management and Handling) Rules,1999 now under serious considerations for an Act of law has many compliance guidelines All cities with the population of more than 10 Lakhs, 1-10 Lakhs, 0.5 to 1 Lakhs and less than 0.5 Lakhs must comply by 31-12-2001 setting up of suitable composting facilities to make use of waste. They must also comply with the identification of landfill sites for future use by 31-12-2000.
 

2.1 ALTERNATIVE COLLECTION OPTIONS 

2.1.1 House to house collection

Collection of garbage from individual House Holds (HH) using waste pickers overcomes at least some of the evils inherent in the conventional system. Door to door collection of sorted or unsorted garbage removes the need for maintaining a roadside bin. Secondly as the primary solid waste is delivered to the waste pickers themselves littering during picking recyclable from the bins is also avoided. Finally USW could be sorted by the rehabilitated waste picker, which in turn would dispose the non – recyclable at pre-designated sites for onward transport or treatment. This arrangement serves purposes, such as greater quantities of USW would be available at a fewer locations making the task of the collection trucks much simpler and effecting greater savings in daily fuel consumption. Examples exist of Non-Governmental Organizations( NGO's) and Community Based Organizations(CBOs) in medium to large cities in India having successfully achieved this objective. Achieving house to house collection would require institutional and infrastructure support by both the formal system and local NGO's / CBO's. Possible modes of collection are given in Figure:01.

2.1.2 Collection from dust bins

Wherever door to door collection systems cannot be organised an alternative system of collecting sources segregated USW in seperate,colur coded road side bins needs to be resorted to. The success of such a collection system depends to a large extent on the motivation of the USW producers as well as the extent to which this necessary discipline can be maintained in its use. A host of other stake holders to facilitate catalytic intervention are also  possible. Inputs for such a intervention could be in the lines of active participation as given at Figure :02.

2.1.3 Transportation mechanism

After collection, the next phase of transpiration involves more than one option. Primary collection by Light Vehicle Transport (LVTs) is conducive to small scale operation Micro Treatment Plant (MTP), 300 kg/d) where aerobic composting, vermi-composting or anaerobic decomposition are the only sensible options. All technologies however, are subject to scales of economy and hence it would be necessary to prioritize treatment objectives before selection of the most suitable technology mix. 

As on date, wherever the local authoririues,CBOs and NGOs have started HH collection segregation container tricycles, and hand pulled carts are used. The design of these community solid waste collection vehicles has gone a critical evolution from a single container tricycle about a decade ago. When privatization of treatment and disposal is favored, which is at present a trend, it will be necessary to operate above an economic threshold. Suggested transport options are given at Figure: 03 and 03a In addition, due to space constraints alternatives to MTPs such as compost production or land fills have to be utilized. To minimize pollution problems it will be necessary to use majority of decomposables in nearby farms. This is already in practice in many cities in India though not in a very efficient manner.

2.1.4 Treatment, disposal and recycling of garbage

Conventionally garbage collected from doorsteps or roadside bins is usually transported for disposal with little or no treatment. At this stage it may be pointed out that it is now possible to treat USW at micro scale (micro treatment plant) to recover value added products locally and reduce the quantity of USW to be treated and disposed in a centralized manner. Possible treatment and disposal options based on existing practices are given at Figure :04 and 05.

3.0 DECENTRALIZED URBAN SOLID WASTE MANAGEMENT - USWM’94’MODEL

The background for development of USWM"1994 Model had been a growing realization on the impacts due to poor management of Urban Solid Waste in the early 1990’s. The practice of indiscriminate dumping of Urban Solid Waste causing adverse 
(a) health impacts - due to air, water pollution and pathogens, 
(b) resources losses 
(c) social negligence of depended populations and 
(d). irreparable ecological damages was realized. 
Newer and viable alternatives had therefore started becoming popular. The relative occurrence of the three main fractions of garbage namely, the (1) recyclable, (2) decomposable and (3) non-decomposable and / or non-combustibles demanded technology options. A strong linkage amongst formal and informal stakeholders in community based solid waste was focused in field study undertaken jointly by the University of Amsterdam and Karnataka State Council for Sciences & Technology (KSCST). . Environmental Sound Technologies for USWM in the process for the sustainable linkages remained obvious spin off benefits.

USWM ‘94 Model emerged as a bench mark based on ongoing community and other stakeholders perception and action prevailing on USW at that time. Field data were collected during 1992-1994 studies at Chennai, Hyderabad and Bangalore. Salient details of the studies with reference ESTs are cited in this paper for discussions.

3.1.1 Recyclable

Glass (as bottles/cullets), paper plastics, metallic wastes (ferrous and non-ferrous), rags etc., constitute about 5-8% of fresh USW. In the conventional road side bins, USW amounting to 6-8% by weight is removed by waste pickers which through one or two intermediate stages reach the now well established recycling industry. In roadside bins, owing to the mix up of different constituents of USW and due to soil contamination, all the potentially recyclable materials cannot be recovered. This could however, be overcome in the door to door mode of USW collection system. It is estimated that about 150 recycling industries exist around Bangalore while a significant portion also leaves Bangalore for distant destinations. In short it may be said that the recycling industries reprocessing the above have been well established. A greater efficiency of recycling could be achieved if much of the domestic USW is source segregated.

3.1.2 Non-recyclable, poorly combustibles

Only selected recyclable are removed from bins leaving behind some potentially recyclable material as mentioned above. In addition, USW contains mineral matter, wood products, unrecyclable scrap, unsanitary wastes, etc. Much of the soiled plastics, though theoretically recyclable are practically difficult to clean before recycling. The soiled plastics though theoretically combustible are known to release many toxic fumes under normal incineration conditions and therefore are best avoided. Until novel technologies to separate the various soiled recyclable are developed these are best disposed by sanitary land filling. Alternatively, an efficient mechanism and incentive for source segregation is likely to alleviate this problem. For most of the technologies considered later for MTP and large scale treatment systems, this fraction is often an inert impurity which can be segregated after the treatment process is completed.

3.1.3 Compostables and fermentables

The USW of most Indian cities contain between 70-85% of decomposable organic materials with high moisture content ranging between 30-65% depending upon the season and localities. Kitchen wastes, food wastes, garden sweepings, trash paper, rags, newspaper trash (packaging wastes), napkins, etc., form the bulk of the decomposable organic wastes. Among this the last type poses hygienic problems while most of the others are naturally decomposable to environmentally safe and products. The high moisture content of this fraction, as well as nearly 24 hour residence time in domestic trash cans enhances the incidence of partial aerobic decomposition. As a result, of this rapid decomposition, USW releases malodorous bi-products which is the major source of nuisance necessitating the USW be cleared everyday. On the other hand in tropical weather conditions the dry climate hastens drying of the moist USW and much of the potential nuisance is reduced in spite poor clearance of USW from bins.

3.1.4 Treatment options for the decomposable fractions

Treatment options aim at rapidly removing the decomposable constituents of USW chemically or biologically and render the remaining stable material pathogen free. Whereas, disposal options aim towards safe containment or reuse. Currently only disposal by indiscriminate dumping is practiced as against sanitary landfills in most cities in India.. Composting, vermicomposating or anaerobic decomposition are biological treatment options for disposal by reuse as manure while incineration or RDF are physio-chemical treatment options where the remaining ash is disposed by land fills.

Inadequate supply of air makes decomposers (bacteria) release partly decomposed compounds which are malodorous. However, when this process is controlled, the plant nutrient rich manure produced is valuable for agriculture and gardening in a nutrient starved agricultural country. Backyard composting pits using kitchen and garden wastes is well known. Space limitations dictate that composting be carried out rapidly on a commercial basis. Vermicomposting involves the use of earthworms to carry out this task. Composting technologies vary according to techniques and micro-organisms employed to reduce nutrient losses, malodorous problems and pathogen kill. Alternatively, such materials may be decomposed under anaerobic conditions which convert the organic matter to a combustible mixture of methane and carbon-dioxide (biogas). 
 

4.0 ENVIRONMENTAL SOUND TECHNOLOGIES(ESTs) VALIDATION

The major criteria underlying the choice of technologies in the Indian context are the 
(1) capital shortage and difficulty in mobilizing large sums for mega projects, 
(2) high cost of primary collection and transport in the conventional systems 
(3) need to rehabilitate and alleviate the waste pickers currently surviving in waste related activities 
(4) difficulties in administering and functioning under a governmental undertaking systems. Therefore, suitable technologies need to be evaluated on the basis of 
(1) Overall capital needed and ability for gradual adoption; 
(2) Overcoming/improving/avoiding the present methods of bin collection and transportation over long distances; 
(3) Labour intensity of the options wherein the present waste pickers themselves may be rehabilitated; 
(4) Small economically viable units – conducive to small enterprise, low overheads, supervision and governmental control/financial support. 
(5) Availability of infrastructure, land etc.

To enhance the efficiency of operation, potential to privatize, provide rolling fund for its perpetuation and provide better working conditions to the rag picker it is necessary to devise ways to increased the financial returns. To achieve this it is necessary to utilize technologies creating value addition to the fermentable portions of USW. Currently a few options are available whose successful deployment depends on several location specific conditions. These are, compost production, vermi-composting, generation of biogas along with vermi-composting or mushroom production, production of Refuse DERIVED FUEL (RDF), sanitary land filling incineration (with or without simultaneous power generation), etc Among these, sanitary land fill may be used as a last resort due to the high costs of USW transportation as well as that of the land around the cities. Incineration may also be used only as a last resort due to the ensuing air pollution problems as well as due to its unfavorable past experience in India. This leaves only four options under the current state of technology, i.e. the first four named above.

All technologies would necessarily work only within specified limits of USW quality as well as local conditions of space availability, local skills, peoples' participation and economy. Many of the linkages would be technology specified and would change with newer technologies. The use of different MTPs would require land in the range of 50-60m2 and anesthetically designed systems could be blended into the landscape of parks and other civic amenities land, thus making it work within available space.
 

4.1 TECHNOLOGY DETERMINANTS

4.1.1. Composting

Providing opportunities to neighboring farms to lift USW at their costs for conversion to compost is the most logical option wherever permissible. The long-term experience in Calcutta indicates little hazard. However, not all USW would be found at a single point for its economic transport to farms and Centralized Composting around CCPs can add value to USW at medium scale (100 tonnes per day) when technology is simple. The Karnataka Compost Development Corporation (KCDC) operates at 90 tpd and is unlikely to expand. Alternate technologies such as that of some industries are potential alternatives. The minimum economic size would be equivalent to handle 7.5t/d (50 LVTs + 10-15 labour) and would necessitate 0.75-0.8 acres for every 40,000 population (@ 200 g/cap/d) producing 800 t/year, gross return = 2.25 lakhs (@ Rs.3.00/t compost). The commercial viability under different constraints is still unclear, especially without support of local bodies. The critical limit of this technology lies in the ability of produce a heap of USW daily corresponding to other values. This technology would provide little by way of returns to small enterprises and is economic only above aforementioned threshold size.

4.1.2 Vermicomposting

Small scale vermi-composting has been attempted by more than two organizations in Bangalore. The minimum economic unit as calculated appears to fit well with the discharge from on tricycle/trolley unit of 250 kg. This with a through put of about 30% would yield about 75kg vermicompost daily using about 60 Sqm of land area and a gross daily return of Rs.150-375. The potential for its rapid marketing of vermi compost, the quantum and sources of water for its operation, novel techniques to reduce malodor during initial aerobic fermentation however still to be understood. Field experience by an NGO seems to indicate that at very low levels of skill and investment this is the easiest first option to adopt. Further, among the options this option can work at the lowest investment and at reasonably high levels of waste picker rehabilitation.

4.1.3 Refuse derived fuel

There is little experience from viable commercial enterprise utilizing USW exclusively as raw material or sustained field experience of running small units on a commercial basis in any city. At present, it is understood that this technology would be economic at larger sizes, namely 30-100 t/d ranges. However, the low calorific value of the USW, the need for its supplementation with other biomass materials, its separation from undersiable components, its supplementation with other biomass materials, its separation from undesirable components, its high moisture content are factors which work against its large scale deployment. Long term field experience with this method is also not available in spite of the fact that today there are entrepreneurs willing to provide technology for units in the range of 30-600 tonnes /day operating range.

4.1.4 Bio-gas with resource recover

In the case of Bangalore USW it was reported that most of the USW collected from the roadside bins had a high content of moist fermentable matter. The high moisture content, need of containment during its initial putrefaction stage, overcoming malodor problems, reduction in its bulk, manure as the ideal end use option etc., indicated that the biogas option was the most sensible way of treatment of USW in Bangalore. Removal of the less offensive spent material for use as manure was then considered the ideal option. Deployment of the biogas option seems possible from 300 kg input per day level upwards and therefore is capable of catering to a decentralized treatment system.. Each decentralized biogas plant would cost about 25,000 INR(Indian Rupees) for 250 kg/d capacity while costs per unit would reduce with increasing size of the plants. It is now possible to couple biogas production from USW with additional revenue generation techniques by reuse of spent material for vermicompost production at this small scale, sale of biogas for domestic cooking, production of power for local illumination, conversion to edible mushroom, etc. this system has a potential to generate the largest amount of net revenue from its deployment. On the other hand like the other technologies mentioned above there is little by way of commercially run systems in the field. Biogas with vermicomposting competes well with vermicomposting alone with regards to criteria such as labour employed per tonne processed, net cash returns per ton processed, with the exception of investment per ton capacity which is in the middle range. Biogas production coupled to mushroom production however, provides the best option if capable of being successfully deployed as envisaged. This necessitates that well segregated USW is made available which is free of pathogen contamination.

4.1.5 Sanitary landfill

The above technologies adopted mostly at levels (compost at large scale) would inevitably generate some non-decomposable which in the long run would accumulate to significant proportions and disposal technologies for it has to be divised. In addition, building debris accounts for a significant portion of the daily solid wastes generated which requires technological options.
 

5.0 MTPM'2000: CASE STUDY 

5.1 Project management

The Waste wise Bangalore undertook the decentralized waste management initiative for Cuttack city under the Cuttack Urban Services Improvement Project(CUSIP). Here Waste Wise put in to practice the door to door collection of waste and its treatment near the source. For the treatment of waste an Invassel Compost Plant was set up at ward no.35. The project got executed during February 2000 to June 2000.

The project was undertaken with inputs from Bangalore and local expertise drawn from Cuttack. The inputs from Bangalore were provided in planning of the services provided, the social component motivating of the various stakeholders in the process and the communication methodologies, the technology for composting of the waste and finally management of the whole process. 4 experts and 4 staff from Bangalore visited Cuttack over the 15 months and provided inputs on the project. The local inputs from Cuttack were for motivation of the community and the the operations staff and ensure the processes go on smoothly. A certain skill transfer on the procedures and technology has also taken place. 2 persons have worked on the project full time.

The project involved four distinct but interconnected and overlapping phrases. A brief summary of these are ;

Phase 01 : Planning stage. Identification of Ward No. 35, identification of neighboring 4 wards for collection process, detailed collection plan for Ward 35. political processes of operationalising the planning, Location and design of composting site. Identification of suitable site for disposal was the most contentious issue.

Phase 02 : Collection system implementation phase, organizing of decentralized waste collection systems,communication design done at Bangalore got translated to Oriya language. Field testing these and freezing on the communication strategy. Implementing the communication strategy and involving the residents, organizing the hardware and motivating the municipal staff to change their approach were taken up. This phase was affected badly for reasons of super cyclone 

Phase 03 : Composting implementation phase. The actual composting started in Feb’2000 and is continuing to work at present. This phase involved getting the hardware in place. 60 days of composting has been brought to 40 days and later further reduced to 30 days by doubling the capacity from 0.5 t to 1.0 ton waste input per day.

Phase 04 : Consolidation phase . Inclusion of neighborhood wards to source segregation and decentralized waste treatment scheme.Motivation of stake holders initiated.

With the completion of this project, demonstration of the feasibility of decentralized waste management as an alternative to centralized waste management has been demonstrated. The major strengths of the decentralized systems are the better waste disposal and long term potential for lower mechanization and generation of local employment. The major weakness is the high requirement of management skills. Hopefully, based on the study results and action plan to follow Cuttack could be one of the first city in India managing all its waste in a decentralized manner.

5.2 Composting Process 

Composting stacks are brick structures like water tanks protected from rain and sun by inexpensive tarpaulin roofs. The organic waste is dumped in to these stacks. At the bottom of the stack there is a plasticized steel mesh for letting excess leachants to drain out of an outlet tube. The bottom floor is sloped to one direction to drain water.The gap between the grid and floor is 100 mm. and the waste is piled on the grid. A Plastic tube in the 100 mm gap is laid which supplies air from an electric blower kept outside the stack.

Photo 02 : When the blower is on air enters all parts of the bottom of the waste and diffuses upwards and nearly uniformly aerates the stacked garbage when the blower is on. 

Composting method adopted is an aerobic microbial one. Aerobic microbes which live in an oxygen atmosphere are used. This process has an advantage of being inoffensive i.e no bad smell.,quick and efficient. It also gets rid of pathogens in the early phases when the temperature rise to approximately 60 deg C and remain high for two or three days in the thermophilic stage.

Phase 01 : Thermophylic : Phase 

The waste is put in the stack and when it is frill covered at the top by dried leaves or rough compost left over from earlier stacks.The volume of the garbage reduces to almost 50 percent its volume once water content in garbage is drained out. No air blowing is required. Temperature rise will kill pathogens of common diseases and complex carbohydrates and proteins will be broken down to form simpler nutrients suitable for plants.

Phase 02 : Mesophylic Phase

After the 5th day air is blown for 2 hours every day. During this phase temperature will drop to 45-30 deg C and sugars will be broken down. If, for some reasons any part of the stack shows anaerobic conditions a mild bad odor could be sensed. In that case, aeration must be prolonged for 4 to 6 hours. After the 21 st day temperature starts dropping.

Phase 03 : Actinomycetes Phase

White fungi appear throughout and cellulose start decomposing. During this phase, C/N ratio decreases and moisture also decreases. Some worms appear helping the process of humus formation. After 25-30 days, the contents of the stack are taken out and spread in a shady place for drying. The dried contents can be sieved with 3mm mesh to get fine powder as manure. The coarse compost can be used for trees etc.,

5.3 Ten procedure guidelines for reference :

1: Segregation at source for plastic and toxic materials for computable is essential.

Water hyacinth can be added liberally. Large pieces of organic waste such as banana leaf,should be cut in to small pieces.

2. Straw, if present it must be on the top for reasons of choking the air flow.

3. After 100 kgs of waste add about 10 kg cow dung. Using pick axe or pitch forks to mix cowdung thoroughly.

4. For five days after the stack is full and closed for composting, blowing of air should be for 15 minutes only to let the waste rise in temperature. The leachate from the outlet pipe at bottom must be collected and could be used with dilution for watering the trees. Temperature is measured and recorded.

5. pH and temperature must be recorded continuously..

6. After the 5th day air should be blown for 2 hours each day.

7. The waste will normally crumble to powdery stuff and by 20th day the waste resemble compost.

8. 25 days after closing the stack contents are taken out and record the weight.

9. Put the contents of the stack in as shady place. 4 hours or more.

10. Sieve the contents using 3 mm sieve.

5.4 Salient features the Plant

5.4.1 Structure of the Plant

40 stacks of 1 ton of fresh waste capacity each . When fully operational will generate an average 300 kgs of compost per day (Photo :02, 02a, 02b). 

An air blower of 1 H.P. rating provides forced aeration for all the stacks.. Diffuser pipes 6.5 m long 50 mm dia with perforations provide the air supply below the waste stack..

100 mm gap is provided above the gentle slope stack bottom and the plastic coated grid supporting the waste (Photo : 03)

A chicken mesh covers the completely filled stacks,to prevent the dispersal of sand particles and attack of predators like dogs, cows, bandicoots, rats and insects.

Four stacks together are connected to a leachate chamber. All leachate chambers collect excess water from stacks which further drains to a tank.
 
 

Photo :02 : Preparation of Stack	Photo:02a :  Transport of partly segregated household waste.
Photo:02b: Segregated  Compostables in the Stack.	Photo : 03 : Air blower  and openings in the tank

5.4.2 Preparation of raw material 

Photo : 04: Monitoring of 
Parameters continuously

• The waste collected initially was 100 kgs and later increased to 300 kgs per day.
• Initially the waste predominantly containing straw, cowdung, inorganic contents with soil particles and less of kitchen waste was used for keeping moisture content low..
• After stabilization of composting process market waste ,hotel waste,house hold kitchen waste and water hyacinth were used.
• Segregation of waste at source was not 100 percent. Non-bio-degradables such as plastic,glass,rubber,metal,cloth etc., were  physically removed.
• Bigger pieces in the organic waste like banana leaves and stem, water melon skin and other large organic waste were separated and chopped in to small pieces.
• Segregated and chopped biodegradable are shifted in stacks
• After filling the stack, it was covered by a thin layer of straw or dry leaves. 

5.4.3. Composting process

Photo 05 : Preparation of the stack

• Aerobic decomposition by using artificial aeration 
• Cowdung used as a source of microbial composting
• Temperature, pH and moisture content monitored continuously
• Initially temperature shot up to 70 deg C.This is maintained for a day to destroy pathogens
• Temperature maintained between 35-60 deg C
• The pH initially went up to 9 and was maintained between 5 to 8.5 in the later stages.
• Moisture content was maintained to feel wet. Water added to increase it and aeration to reduce.
• Blackish brown fine texture indicate compost was ready. It is at pH 7 and ambient temperature.
• Compost spread over a tarpaulin for two days to remove excess moisture.
• Compost is sieved over a 3 mm mesh and packed.
• The residue was put back to the stack for further decomposition.
• Typically over 30 percentage of waste is converted as compost.

5.4.4 Manpower

• Two workers were employed to handle the process in the plant. One was the Compost Assistant and the other being the Watchman.
• Due to the increase in the quantity of the waste and the operation in the number of stacks labour was inadequate in later stages. As a result the compost was not removed on time from the stacks.

5.4.5 Insights after the implementation 

• The waste in stack 1 was rich with soil particles and inorganic contents mainly because of inadequate segregation. The cause for this this inadequate segregation was the lack of labour.
• It took 8 days instead of 2 days to fill the stack 2. This is one of the reason for the prolonged composting process, which took 45 days.
• There was no roof from stacks 5 on wards till 15 April 2000. The waste in stack 5 and 6 had lost its moisture content to a great extent due to direct exposure to sunlight. Despite water being added, it got evaporated resulting in the prolonged composting process.
• Stack 7 and 8 were also exposed to direct sunlight. But the presence of water hyacinth to a certain extent balanced the moisture content of these stacks.
• The 3 mm sieve of size 550 mm X 800 mm was small and took long time for sieving.
• A single I hp blower was used for all the stacks for the purpose of aeration.
• Electricity was used illegally and the switch boards were inadequate for the blower.
• After the segregation, the unwanted waste mainly comprising the inorganic contents was disposed at the river close to the composting plant.
• Water was easily available at the site

5.4.6 Characteristics of their compost

Four samples of Compost were analyzed one from each stack. Partly segregated waste was further segregated at the plant and non organic materials removed. Thus, the Compost is found to posses a decent quality for use.

The analysis results of the Compost are presented below at Table :01.

5.4.7 Trouble shooting and preventive measures

In the process of Composting certain symptoms and remedies were learnt. The reasons for these symptoms and action taken are documented at Table :02 

Table :02 : Typical Symptoms and Remedies

5.4.8 Economies of 1 ton fresh waste per day plant:

The economical viability of the MTP’2000 works out to 7 years . There are managed costs which could be further reduced. The final cost of treatment could be known only after the consolidation of the ongoing Invassel system is fully optimized for its material balance and aeration procedure. The Cost details are given at Table : 03

Table : 03 : Pay back calculations for one ton plant
 

5.4.9. Typical stack compost results available ( Operations are still on)

Material flow analysis on the system reveal that on an average about 30 percent of the raw compostables are converted to quality Compost. The duration is also varying from 22 to 49 days. The duration could be further reduced based on the experiences of monitoring the dependent parameters in composting. Table 04 furnishes on weight basis the raw waste put in to the stack and compost after sieving and the duration for each stack.

Table : 04 : Stack wise compost conversion in weight and duration in days 
 

5.5.10 Further recommendations to improve performance

• The heavy steel pillars and girders used for roofing the stacks are not necessary.
• Platforms for handling the waste,curing and sieving with roofing are necessary.
• Four blowers are necessary when the plant is fully operational.
• It is necessary to increase the size of the sieve to minimum 800 mm X 1300 mm.
• Two Compost Assistant and a one Watch man are adequate for 1 ton per day Composting.
• Care should be taken to prevent workers physical contact with the waste.
• To prevent re-handling of waste, improved segregation at source must be aimed at.
• Ideally a moisture measuring equipment would be handy in monitoring the system.
• A mechanism to dispose the left over inorganic waste in a local/centralized landfill is preferable.
• Proper electrical connections are necessary with switch boards at regular intervals.

6.0 INFERENCES

The alternative urban future in developing countries by environmentally benign strategies with community participation in making best use of local skills, knowledge, culture and resource is essential for sustainable Municipal Soild waste management. While the ESTs and working models are always available as far as technology is concerned, implementation of a decentralized preventive waste management strategy requires coordination among various categories of agencies viz., Government and local bodies, NGOs and CBOs technologists entrepreneurs and industrialists, bankers and financiers, mass media and mass educators, citizens, etc. In order to achieve this coordination a network needs to be formed with representatives from the above sections of the society. 

The network at local levels would also need to perform tasks such as, 
(1) Promotion of micro level organisations to initiate, organize and manage house to house collections, by – identification of organizations, guiding and motivation, assessing feasibility providing seed capital and infrastructure, monitoring, etc.; 
(2) Promotion of establishment of MTPs; by – identification and assessment of suitable technologies, training and motivation of potential entrepreneurs (waste picker, CBO/NGO, individuals etc.), assisting in procuring seed capital etc.; 
(3) Liasoning with local bodies at various stages;
(4) Mass education; by – production of audio-visual and print material, campaign, etc.; 
(5) Identify various sources of funds to facilitate the above; 
(6) development of new technologies and upgrade existing systems.

7.0 ACKNOWLEDGMENT

Profound thanks to Mr.Anslem Rosario, Director,Waste Wise, for freely sharing information on project at Cuttack,Orissa India. Sincere thanks to Dr.Isa Baud, Professor, Department of Human Geography, University of Amsterdam , The Netherlands and Karnataka State Council for Science and Technology, Karnataka and Dr.Chis Furedy, Professor Emeritus, York University, Canada who with a host of researchers as a team established vital insights in urban solid waste management at Hyderabad,Chennai and Bangalore,India. Author served as a member in the steering committee of the project. Special acknowledgement to my daughter Sahana J for computer support in the preparation of this paper.

8.0 REFERENCES

Draft Notification of The Municipal Solid Wastes(Management and Handling) Rules,1999, MOEF,GOI,1999

Proceedings of the Workshop on linkages between formal and informal actors in CBSWM, University of Amsterdam, The Nether lands and Karnataka State Council for Science and Technology, Bangalore, April 1994.

Technical Report- Invassel Compost Plant, Cuttack, Waste wise, Mythri Sarva Seva Samithi (e-mail : mss@vsnl.com attn : Mr.Anslem Rosario, Coordinator, Waste Wise UN Asia-Pacific’2000 initiative,1997

UNEP-IETC,1992, Environmental Sound Technology data base maESTro URL : http://www.unep.or.jp/ietc/ESTdir/maestro/setup2.html.