Sudhakar Yedla

DEVELOPMENT OF A PURPOSE BUILT LANDFILL SYSTEM FOR THE CONTROL OF METHANE EMISSIONS FROM MUNICIPAL SOLID WASTE

In the present paper, a new system of purpose built landfill (PBLF) has been proposed for the control of methane emissions from municipal solid waste (MSW), by considering all favourable conditions for improved methane generation in tropical climates. Based on certain theoretical considerations multivariate functional models (MFMs) are developed to estimate methane mitigation and energy generating potential of the proposed system. Comparison was made between the existing waste management system and proposed PBLF system. It has been found that the proposed methodology not only controlled methane emissions to the atmosphere but also could yield considerable energy in terms of landfill gas (LFG). Economic feasibility of the proposed system has been tested by comparing unit cost of waste disposal in conventional as well as PBLF systems. In a case study of MSW management in Mumbai (INDIA), it was found that the unit cost of waste disposal with PBLF system is seven times lesser than that of the conventional waste management system. The proposed system showed promising energy generation potential with production of methane worth of Rs. 244 millions/y (

Economic evaluation of a landfill system with gas recovery for municipal solid waste management: a case study

5.2 million/y). Thus, the new waste management methodology could give an adaptable solution for the conflict between development, environmental degradation and natural resources depletion.

Economic insight into municipal solid waste management in Mumbai: a critical analysis

Economic activity uses resources, which leads to waste generation. With rapid industrialisation and urbanisation, per capita solid waste generation has increased considerably. Solid waste generation data for last two decades shows an alarming increase. Owing to its improper and untimely collection, the transport and disposal of municipal solid waste poses a severe threat to various components of the environment and also to public health. This paper describes the merits and demerits of various technological aspects of solid waste management. Landfill technology, as it is the most widely employed and is regarded as the most suitable and simple mechanism, especially for tropical countries such as India, is emphasised. All possible costs and benefits and externalities are examined. A cost-benefit analysis of a landfill system with gas recovery (LFSGR) has been carried out for Mumbai citys solid waste, accounting for certain external costs and benefits, and found that it could make a huge difference of savings of about Rs. 6.366 billion (approx.

Modified landfill design for sustainable waste management

0.l40 billion) per annum with reference to the existing system of waste disposal.

Adsorption of hexa-valent chromium using treated wood charcoal - elucidation of rate-limiting process

Mumbai generates 6256 tonnes of waste every day, of which 17.20% is recyclable, but only a fraction of this is retrieved by rag-pickers. The economic value of the retrieved material is not considered by the Municipal Corporation of Greater Mumbai in valuing the waste management system as there is no retrieval mechanism except the informal rag-picking activity. Moreover, the cost of land used for the dumping of waste is also not accounted for. In the present paper, a comprehensive cost-benefit analysis for the present system of municipal solid waste management in Mumbai is carried out, with due consideration for implicit or hidden costs and benefits. Accounting for the implicit costs and benefits showed a difference of

Removal mechanism of endosulfan sorption onto wood charcoal

6 per every tonne of waste disposal. This could show a considerable difference in policy development at the municipality level. Demand supply analysis proved that the present system of waste management would not yield a feasible market solution without private sector participation. With the increasing demand for improved waste management, private sector participation is essential and a Pigouvian tax is a necessary tool to make the private sector participation in solid waste management a success.

Replication of urban innovations – prioritization of strategies for the replication of Dhaka’s community-based decentralized composting model

Waste management, being one of the most important aspects of urban development, is gaining importance among developing nations. Landfills, which were initiated for hazardous waste management and subsequently transformed into sanitary landfills, have been the most widely adapted practice for municipal solid waste management worldwide. However, the conventional design of landfills not only fails to fulfil the needs of waste management but also fails to target optimal resource recovery and energy generation. In the present study, modified design was proposed for partially engineered landfill system based on theoretical considerations. Its potential for energy generation and resource utilisation was analysed with a case study of Mumbai municipal solid waste. It was found that the system with modified design could yield 0.157 million tons of landfill gas (0.145 million tons of coal equivalent) out of one year of solid waste. Further, this could recover resource valued at US

Development of a methodology for electronic waste estimation: A material flow analysis-based SYE-Waste Model

2.49 million per year.

Removal of endosulfan using aerobic mixed bacterial culture

In the present study, locally available wood charcoal was used as an adsorbent to remove Cr (VI) from water. It was found to be giving poor removal efficiency whereby only 19% of Cr (VI) was removed. Considering the fact that wood charcoal possesses a honeycomb structure, an acid treatment was tried with HCl, H2SO4 and HNO3. Treatment with concentrated hydrochloric acid has improved the removal efficiency of wood charcoal to 94%. Kinetic studies were carried out with various systemic parameters, namely initial Cr (VI) concentration (0.5, 1, 2 mg/L), adsorbent size (0.11, 0.18, 0.25, 0.36, 0.51 mm) and agitation speed (130 to 180 rpm) to understand and determine the equilibrium time, order of reaction, rate constants, diffusion coefficients, and to determine the maximum adsorption capacity and also the rate limiting process. It was found that the uptake of Cr (VI) onto wood charcoal reached equilibrium within the first 6 h of contact time. Isothermal studies explained by using the Freundlich model revealed that the maximum adsorptive capacity (Qmax) of the treated wood charcoal is 677 µg/g, which is well within the standard/feasible value for a wood‐based charcoal. The process limiting the rate of adsorption (rate limiting step) was analyzed using the kinetic data as well as using various systemic parameters such as initial Cr (VI) concentration, adsorbent size, and agitation speed was finally confirmed by the multiple interruption test. It was concluded that the adsorption process was controlled by film diffusion.

Development of techno-economic integrated models: LFSGR and aerobic composting for municipal waste management

Endosulfan is among the most widely used pesticides in developing countries and other parts of the world and has been found to contaminate various parts of the environment, including drinking water sources. In an earlier study to find a suitable adsorbent to remove endosulfan, wood charcoal was found to give promising results. In the present study, the process controlling the rate of endosulfan sorption onto wood charcoal and the mechanism of removal were examined using various methodologies. Both film and pore diffusion coefficients were determined, and the linearity of the rate constants of adsorption with initial endosulfan concentrations revealed the process to be controlled by film diffusion. This was supported by the linear fit of the rate constants with the inverse of the diameter of adsorbent particles and the change in adsorption rates with agitation speed. Multiple interruption tests also revealed that endosulfan sorption onto wood charcoal is controlled by film diffusion. The increase in reaction rate constant with temperature and isosteric heat of adsorption in the range of -2.655 to 5.185 kcal/mol implied that the endosulfan removal process was endothermic in nature. The activation energy of 2.33 kcal/mol, which was less than 12 kcal/mol, revealed that the removal mechanism could be attributed to physisorption with a major contribution of van der Waals and electrostatic forces.