source:http://209.85.175.104/search?q=cache:_q99uaPixzIJ:fincomindia.nic.in/fincomnet/rpt_intra/swm_rpt%2520part1.doc+details+design+of+vermi+composting+plant+11+MT+per+day&hl=en&ct=clnk&cd=9&gl=in
Introduction
This chapter studies in details six ongoing waste management schemes/programmes/projects in India. While two of these projects concentrate on composting and recycling, four concentrate on waste-to-energy projects. The earlier study includes the Bangalore model and the Jaipur model. For waste-to-energy projects, facilities in Lucknow, Hyderabad, Vijaywada and Nagpur have been studied. The studies also highlights on the environmental and cost sustainability of these projects/programmes. Inputs from these studies have been used to develop pilot cases, along with their cost and financing options; these are outlined in the following chapter. In order to facilitate understanding of the technologies used in these eight cities, short write-ups on some of the technologies used/available have been outlined below. Merits and demerits of some of these technologies are also outlined to assist any policy maker in identifying the best alternate solution to waste disposal depending on local conditions.
3.2 Technologies Available for Municipal Waste Disposal
3.2.1 Composting
Composting is defined as a controlled process involving microbial degradation of organic matter (MoEF, 1999). There are various types of composting, but they can be categorised into three major segments – aerobic composting, anaerobic composting and vermicomposting.
Anaerobic Composting
In this form of composting, the organic matter is decomposed in the absence of air. Organic matter may be collected in pits and covered with a thick layer of soil and left undisturbed for 6-8 months. The compost so formed may not be completely converted and may include aggregated masses (CEE, 2000).
Aerobic Composting
A process by which organic wastes are converted into compost or manure in presence of air, aerobic composting may be of different types. The most common is the Heap Method where organic matter needs to be divided into three different types and need to be placed in a heap one the other, covered by a thin layer of soil or dry leaves. This heap needs to be mixed every week and it takes about 3 weeks for conversion to take place.
In the Pit Method the same process as above in done, but in pits specially constructed/dug out for this purpose. Mixing has to be done every 15 days and there is no fixed time in which the compost may be ready (depends on soil moisture, climate, level of organic material, etc.). The Berkley Method uses a labour intensive technique and has precise requirements of the material to be composted. Easily biodegradable material, such as grass, vegetable matter, etc., are mixed with animal matter in the ratio of 2:1. This is piled and mixed at regular intervals. Compost is usually ready in 15 days (CEE, 2000).
Vermicomposting
Vermicomposting involves use of earthworms as natural and versatile bio-reactors for the process of conversion. Vermicomposting is done in specially designed pits where earthworm culture also need to be done. As compared to above, this is a much more precision-based option and requires overseeing of work by an expert. It is also a more expensive option (especially O&M costs are high). However, unlike the above two options, it is a completely odour less process making it a preferred solution in residential areas. It also has an extremely high rate of conversion and so quality of end product is very high with rich macro and micro nutrients. The end product also has the advantage that it can be dried and stored safely for longer period of time.
3.2.2 Waste-to-Energy: Thermo-Chemical Conversion
Incineration
Incineration is the process of controlled combustion at around 800oC for burning of wastes and residue, containing combustible material. The heat generated during this process can be recovered and utilised for production of steam and electricity. This method is usually used to achieve maximum volume reduction, especially where there is a shortage of landfill facilities. It is also usually a cost effective method o disposal (CPCB, 2000). However, in Indian conditions, it is not always very successful due to the low calorific value of Indian wastes (low combustible material). Also it is not classified by the MNES as an innovative practice and so looses out on many incentives otherwise provided by the MNES for WTE plants.
Pelletisation
This refers to creation of fuel pellets (also called refuse derived fuel or RDF) from MSW. Pelletisation generally involves segregation of incoming waste in to low and high calorific material followed by separate shredding. Different heaps of shredded wastes are mixed together in suitable proportions and solidified to produce RDF pellets. Pellets are small cylindrical pieces with a calorific value of 400Kcal/kg. Since this is quite close to calorific value of coal, it can be used as a substitute. However, calorific value of the pellets completely depend on the calorific value of the waste stream which needs to be sorted in Indian conditions to allow only the right type of waste to come through.
Pyrolysis/Gasification
In this process, combustible material is allowed to dry/dewater and is then subjected to shredding. These are then incinerated in oxygen deficient environment (pyrolysis). Gas produced from this process can be stored and used as combustible source when required. However, quality of the gas also depends largely on quality of waste stream and requires high calorific value waste inputs. Different types of pyrolysis/gasification systems are available which can be used depending on local conditions; some of these include Garrets Flash Pyrolysis process, ERCB process, Destrugas Gasification process, Plasma Arc process, Slurry Carb process, etc. Recent studies for Indian scenario clearly show that while net power generation for thermo-chemical conversion processes is around 14.4 times the quantity of waste input (in kW), the same for bio-chemical conversion process is 11.5 times the waste inputs (provided 50% of waste inputs are volatile solids). However, in terms of environmental impact, the later is far safer option than the previous.
Bio-Methanation
While bio-methanation is generally classified as a WTE process, unlike the previous three alternatives, which use thermo-chemical conversion, this uses bio-chemical conversion similar to composting process. It basically taps the methane gas generated from the bio-chemical reaction in wastes dumped in aerobic digesters.
Landfill Gas Recovery
Energy Recovery from Waste-to-Energy Plants
Recent studies for Indian scenario clearly show that while net power generation for thermo-chemical conversion processes is around 14.4 times the quantity of waste input (in kW), the same for bio-chemical conversion process is 11.5 times the waste inputs (provided 50% of waste inputs are volatile solids). However, in terms of environmental impact, the later is far safer option than the previous.
Similar in principal to the bio-methanation option, this process taps and stores gas produced in sanitary landfills. Typically, landfill gas production starts within a few months after disposal of wastes and generally lasts till 10 years or more depending on composition of waste and availability/distribution of moisture.
3.3 Advantages and Disadvantages of Various Options
Table 4.1 and 4.2 highlight some of the advantages and disadvantages of various options discussed have been outlined in the following page.
Table 3.1: Advantages and Disadvantages of Waste Disposal Systems (in Indian Scenario) – Composting
| S.No | Item | Aerobic Composting | Anaerobic Composting | Vermicomposting |
| Foul odour in process | Yes | Yes | No |
| Quality of End Product | Moderate | Moderate to Good | Good to Excellent |
| Time for Composting | 2-3 weeks | 6-8 months (minimum) | 6 months (minimum) |
| Use for production of gas (CH4) | No | Yes (in controlled environment) | No |
| Attracts rodents, pests, dogs, etc. | Yes | No | No |
| Need for Constant Monitoring | Low | High | Very High |
| Storage capacity of end product | Low | Low | High |
| Market demand | Moderate | Moderate | High (for agriculture) |
| Power requirements | Yes (if mechanised) | No | Yes |
| Intensity of skilled labour requirement | Low | Moderate | High |
| Land requirement | Low | Moderate | High |
| Quality of waste segregation | Moderate | High | Very high |
| Leachate pollution | High | High | Low |
| Contamination of aquifers (large scale) | High | Moderate to high | Low |
| Capital Investment | Moderate | Moderate | High |
| O&M Costs | Moderate | Moderate | High |
Table 3.2: Advantages and Disadvantages of Waste Disposal Systems (in Indian Scenario) – Waste-to-Energy
| S.No | Item | Incineration | Pelletisation | Pyrolysis | Bio-Methanation | Landfill Gas Recovery |
| Requirement for segregation | High | Very High | High | High | |
| Energy recovery (in optimum conditions) | Around 14 times waste stream | Around 14 times waste stream | Around 14 times waste stream | Around 11 times waste stream | Around 11 times waste stream |
| Direct Energy Recovery | Yes | No | Yes | No | No |
| Overall efficiency in case of a small set up | Low | Low | Moderate | High | Low |
| Efficiency in case of high moisture | Very low | Very low | Low | Moderate | Moderate to High |
| Land requirement | Low | Low | Moderate | Low to Moderate | High to very high |
| Transportation costs | Moderate | High | High | High | Very high (depends on location of landfill) |
| Ability to tackle bio-medical and low-hazard waste | Yes | No | Yes (to some extent) | No | No |
| Concerns for toxicity of product | High | NA | NA | NA | Moderate to High |
| Leachate Pollution | None | None | None | High (in case of no protection layer) | High (Landfill) Low (Sanitary Landfill) |
| Concern for Atmospheric Pollution | High (not easy to control) | Moderate | Moderate (easy to control) | Low | Moderate |
| Sustainability of source/ waste stream | Moderate | Low | Low | Low | High |
| Capital Investment | High | Very High | Very High | Very High | High |
| Power requirements | | | | | |
3.4 Decentralised Waste Management and Composting – Bangalore
Background
This study concerns entirely with the Integrated Urban Environment Improvement Project (IUEIP). The IUEIP was launched in areas falling under jurisdiction of Bangalore Development Authority (BDA) in 1998 and was piloted in 4 BDA schemes. Supported by the Norwegian Embassy (NORAD), this project was designed as a collaborative effort of NGOs, government agencies and resident groups. The IUEIP addressed four main components:
- Integrated plan for environment management.
- Preparation of GIS.
- Open space management.
- Creation of a project secretariat.
This study focuses on the first component only. Close to the beginning of the new millennium, the BDA recognised the need to adopt alternative means for environmental improvement as an integral part of entering the new millennium. In 1998 it designed an alternative approach to developing and maintaining civic amenities through an integrated urban environment plan. The plan was based on a holistic approach, with an in-built system for coordination between various agencies, and with the local residents as the focus of activity. The adopted a 'stakeholder' approach, drawing in resources of NGOs and local residents to address specific issues in the areas, thereby creating and building community awareness of neighbourhood management.
Stakeholders/Partnerships
Primary Stakeholders: Residents of the 4 target schemes and BDA were the primary stakeholder with an overall objective of handing over the area to BMP with an existing plan in place.
Funding Agency: NORAD (Government of Norway)
Technical Stakeholders: Centre for Environment Education (CEE), Tata Energy Research Institute (TERI), Myrthri Sarva Seva Samiti and Technology Informatics Design Endeavour (TIDE).
Other Stakeholders: resident associations, waste scavengers, BMP, BWSSB, KPTC, Bangalore City Police, BMTC, other civic and emergency services of city.
Description of the Project
The SWM component of the IUEIP focussed on development of local level plans for segregation at source, reduction of waste at primary levels, decentralised composting and marketing of end products, recycling, and transfer of wastes to secondary collection points.
The first step included a detailed study and survey of the four schemes to generate information on quantity and quality of waste, water sources, sewerage and drainage systems, existing waste practices in waste management, and identification of suitable land for setting up of composting facilities. This information was used to develop an action plan which was discussed with the residents and approved.
Before execution of the plan, a thorough environmental education (EE) programme was undertaken and all residents, commercial users, servants, etc., were covered. Different technique of EE were used depending on socio-cultural lifestyles of target groups. Most important component of EE was need for quality segregation at source.
Simultaneously waste management committees were set up to monitor and manage the programme. Members of WMCs were trained by the technical experts. Door-to-door segregated collection was initiated in August 1998. All wastes were transferred in specially designed low-cost rickshaws. Localised compost plants were constructed and all biodegradable wastes were transferred to the compost facility. All recyclables were sold by the waste collectors (erstwhile rag pickers, scavengers, etc.) which added to their monthly remunerations. The monthly remunerations of the waste collectors was fixed. Remaining waste (low quantities of recyclables, soiled wastes, and hazardous wastes) are transferred to secondary collection points of BDA.
Compost Facilities
Localised compost facilities were set up in the residential area. Usually an open ground or buffer area was preferred. Eight compost facilities were installed for the first two layout schemes. Although composting facilities originally used aerobic decomposition, they are now being converted to vermicomposting technology with special microbial cultures obtained from the University of Agriculture Sciences, Bangalore in a step-to-step process. This switch will take time since vermicomposting is a more expensive option and requires large capital and O&M investments. The compost pits are of the size of 9 x 4 x 3 ft and it takes an average of 60 days for a compost to be ready, which is then sieved to retrieve the finer compost, while the coarser compost is put back into the pits with fresh garbage. All compost pits are lined with bricks and waterproof material and have sheds over them to protect them from rain and sun. Mesh wires have been provided around the facility to keep away stray animals (see picture).
Financial Outlay
The IUEIP has a three-year time span for execution. The budgetary provision included Rs.363.28 lakhs with funding from NORAD accounting for Rs.290 lakhs (around 80% of the budget) and the remaining Rs.73.28 lakhs contributed from implementing agencies. The O&M costs are recovered from residents and sale of compost to residents and outsiders.
Cost Recovery
Households need to pay Rs.15 per month to the WMC which manages the bank account jointly with CEE. Composts are sold at Rs. 2/- per kg to residents and Rs. 6/- per kg to outsiders. Vermicompost, which has a large market demand, is sold at Rs.7.50/- per kg. One of the biggest purchasers of this compost has been the Horticulture Wing of BDA which uses it in its parks, medians, buffers, etc.
Management Issues
The management of the entire project lies with the WMCs with support from the local NGOs. The monthly remuneration for the workers, overhead charges, and O&M costs from running the project as well as the compost facilities are managed by the WMC from the monthly charges collected from residents and shopkeepers.
Environmental Hazards
This is a low environmental hazard procedure. It results in waste reduction at primary level, which have a direct environmental benefit. This reduces the load on the landfills as well as reduce transportation costs and thus, environmental costs from lesser fuel usage. The negative side effects of aerobic composting (foul odour) has been done away with time and shifting in parts to vermicomposting. Use of lined pits (lined with brick and waterproof) ensures that there is no leaching, especially during rainy season. These pits have been covered to protect them from direct rain and fenced to protect them from stray animals. Over a period of time a 'green screen' consisting of trees and bushes have been created to visually cut off the compost facilities from surrounding areas (see picture).
Marketability Issues
The compost produced from these facilities is of good quality; they are being used by neighbouring agriculture farmers (who use the coarse compost as it is better suited for rice produce), organic farming industry, floral industry, etc. The Horticulture Wing of BDA is another major buyer of this compost and uses it for improving greenery on medians, buffers, parks, etc. (see picture). Improved SWM in these colonies have also had an impact on cost recovery for other services, with residents more willing to pay for water supply, sewerage and drainage services. Real estate values of these areas have also gone up.
Sustainability Issues
Operating Parametres of the Composting Plant of m/s Excel Industries, Mumbai
| Volume of Garbage: 450 m3/day | Weight of Garbage: 300 TPD |
| Quality of Garbage: Unsegregated | Total Land Requirement: 6 Ha. |
| Capital Investment (excluding land cost: Rs. 2.5 crore | |
| Value of Product: Rs.1300/ton | Net Return per ton of Garbage Processed: Rs.100-120 |
Source: FEC & Delphi, 1997
Although the IUEIP is over, SWM in the target areas is still ongoing managed by WMCs. In fact, WMCs have been able to recover enough money from residents and sale of compost not only for sustainable management, but also for shifting from aerobic form of composting to vermicomposting, which is a more costly, though environment-friendly, option. Following the demonstration of success of this initiative, many other colonies/schemes in Bangalore have taken up similar initiatives on their own. Therefore, at a decentralised level, this is a sustainable project and this technology/process can be easily transferred to other cities in
