Sukumar Devotta

Assessment of the status of municipal solid waste management in metro cities, state capitals, class I cities, and class II towns in India: an insight.

Solid waste management is one of the most challenging issues in urban cities, which are facing a serious pollution problem due to the generation of huge quantities of solid waste. This paper presents an assessment of the existing situation of municipal solid waste management (MSWM) in major cities in India. The quantity and composition of MSW vary from place to place, and bear a rather consistent correlation with the average standard of living. Extensive field investigations were carried out for quantification, analysis of physical composition, and characterization of MSW in each of the identified cities. The MSW management status (per the MSW Rules, 2000) has also been assessed, and an action plan for better management has been formulated; both are presented in this paper. Studies carried out in 59 selected cities in India have revealed that there are many shortcomings in the existing practices used in managing the MSW. These shortcomings pertain mainly to inadequate manpower, financial resources, implements, and machinery required for effectively carrying out various activities for MSWM. To overcome the deficiencies in the existing MSWM systems, an indicative action plan has been presented incorporating strategies and guidelines. Based on this plan, municipal agencies can prepare specific action plans for their respective cities.

Production and Recovery of Lactic Acid for Polylactide—An Overview

In the recent past the ultimate disposability of synthetic plastics has been a greater environmental concern, and it has triggered the R&D efforts in the designing of material with an environmentally friendly life cycle by integrating material design concepts with ultimate disposability, resource utilization, and conservation. Traditionally, all plastics have been manufactured from nonrenewable petroleum resources, and these plastics are nonbiodegradable. Conventional disposal methods include incineration and secured landfill, which are associated with many environmental problems, such as production of dioxins. The continued depletion of landfill space and problems associated with incineration have led to the development of biodegradable plastics such as polylactides (PLA), which are manufactured from lactic acid that in turn is produced from starch. Although production processes for lactic acid and PLA are well known, very few processes have been commercialized and still the cost of PLA is not competitive with synthetic plastics. The crux of the PLA production technology is the fermentative production of optically active lactic acid and its recovery. Many processes are reported in the literature and through patents for the recovery of optically active lactic acid and still offer an extensive scope for research and development. This article critically reviews the production and recovery processes for lactic acid and PLA production.

Flue gas desulfurization: Physicochemical and biotechnological approaches

Various flue gas desulfurization processes —physicochemical, biological, and chemobiological—for the reduction of emission of SO2 with recovery of an economic by-product have been reviewed. The physicochemical processes have been categorized as “once-through” and “regenerable.” The prominent once-through technologies include wet and dry scrubbing. The wet scrubbing technologies include wet limestone, lime-inhibited oxidation, limestone forced oxidation, and magnesium-enhanced lime and sodium scrubbing. The dry scrubbing constitutes lime spray drying, furnace sorbent injection, economizer sorbent injection, duct sorbent injection, HYPAS sorbent injection, and circulating fluidized bed treatment process. The regenerable wet and dry processes include the Wellman Lords process, citrate process, sodium carbonate eutectic process, magnesium oxide process, amine process, aqueous ammonia process, Berglau Forchungs process, and Shells process. Besides these, the recently developed technologies such as the COBRA process, the OSCAR process, and the emerging biotechnological and chemo-biological processes are also discussed. A detailed outline of the chemistry, the advantages and disadvantages, and the future research and development needs for each of these commercially viable processes is also discussed.

Particle Size Distribution in Ambient Air of Delhi and Its Statistical Analysis

Particle size distribution in ambient air has been studied in an urban city, Delhi. Different activity sites namely; kerbside, industrial and residential were selected for the study. The statistical analysis was carried out to study the frequency distribution and sources of different particle size fractions. The dominance of coarse particles attributed to local activities was observed at all the sites. It was observed that at kerbside sites, up to 52% of the particles were lower respiratory tract and up to 47% of the particles were upper respiratory tract particles. At residential and industrial sites, up to 40% and 31% were lower and upper respiratory tract particles, respectively. Factor analysis results indicated auto-exhaust as the dominant source of particulate matter at two of the kerbside sites. Resuspended dust was dominant at remaining two kerbside and residential sites. It was inferred using geometric standard deviation of particle size fractions that these were from different sources at residential and industrial site and from similar sources at three of the kerbside sites.

Estimation and allocation of solid waste to bin through geographical information systems

This study presents a geographical information system (GIS)-based procedure for the precise estimation of solid waste generation, computed using the local population density and income group distribution. Using a triangulated irregular network (TIN) in a GIS environment, the procedure further determines the command area for waste allocation to a particular bin which is generally located so the route slopes towards the collection points for ease of transportation by cart pullers. Computational results of bin location, type, size and the frequency of removal are presented for a typical urban area with known population density, income group distribution, road network and topology.

GIS-based locational analysis of collection bins in municipal solid waste management systems

Solid waste management systems currently receive wide attention, from both economic and environmental planners, because of their complexity during coordination of various management strategies. The efficiency and cost effectiveness of route optimization and disposal site selection depend largely upon the appropriate placement of storage bins and their corresponding command area for waste contribution. The present paper illustrates a geographic information system (GIS) based algorithm for optimal location and number of storage bins, considering p-median constrained model, based on Indian guidelines for Municipal Solid Waste Rules. The algorithm also computes the contributing command area of solid waste to a particular bin, based on the shortest distance, with descending slope for ease in solid waste collection.

Statistical Interpretation of Weekday/Weekend Differences of Ambient Particulate Matter, Vehicular Traffic and Meteorological Parameters in an Urban Region of Kolkata, India

An air quality sampling program was designed and implemented to collect data on ambient PM10, TSP, vehicular traffic and meteorological parameters at weekdays and weekends from November 2003 to November 2004 in Kolkata. Educational institutions and most offices and small-scale industries are closed during weekends. Meteorological parameters were measured by the Indian Meteorological Department, Kolkata. Air quality monitoring was performed weekly for 24-h periods at residential (Kasba) and industrial (Cossipore) sites in an urban region of Kolkata and weekday/weekend differences were compared at both the monitoring sites. Significantly higher weekday values of PM10 and vehicular traffic were observed. The daily average PM10 concentrations on weekdays and at weekends were, respectively, 147.7 and 125.5 g·m 3 at the residential site and 212.3 and 186.3 g·m 3 at the industrial site. Corresponding TSP concentrations were 288.4 and 391.9 g·m 3 and 229.6 and 344.9 g/m3. Average traffic flow for weekdays and weekends were 2.3 104 and 1.9 104 vehicles at the residential site and 2.8 104 and 2.4 104 vehicles at the industrial site. There was a strong linear relationship between PM10 and TSP (R2 >0.90) during weekdays at the residential site and at weekends at the industrial site. TSP had moderate (R2 >0.50) linear relationship with PM10 during weekends at the residential site and good (R2 >0.75) linear relationship during weekdays at the industrial site. The Spearman rank correlation coefficient showed that measured particulate pollutants had an inverse correlation with rainfall, temperature and relative humidity at both sites. Average PM10/TSP ratio was moderately correlated (r>0.50) with average vehicular traffic.

Hazardous Waste Management System in India: An Overview

Lack treatment and disposal facilities causes hazardous wastes (HWs) to ravage municipal landfills and open spaces, raising serious environmental threats. Rapid industrialization over the last few decades has indiscriminately increased HW generation in India. In March 2000, the total HW generated was estimated to be 4.41 metric million tonnes (Babu and Ramkrishna, 2003). Adding to this woe are the substantial quantities of HWs being imported for recycling. Large quantities of HWs generated include used batteries, used and waste oil, broken fluorescent lamps, cleansing chemicals for wastes, pesticides past their expiration dates, and so forth. There are only a few well-established treatment, storage, and disposal facilities (TSDF), which precludes effective enforcement of regulations for HW generated from the industrial or nonindustrial sector. The guidelines issued by the Ministry of Environment and Forests (MoEF), Government of India, and the Central Pollution Control Board (CPCB) are available for selection of the best sites for TSDF and for establishing secured landfills (MoEF Guidelines, 1989, as amended in 2003). Only Gujarat, Maharashtra, and Andhra Pradesh states have TSDFs, though not in sufficient numbers and sizes to cater to the entire quantity of HWs generated (Babu and Ramkrishna, 2003). This article focuses on the current status, problems and challenges, policy issues, and future strategies for improvement in HW management system in India.

Anaerobic digestion of vegetable market waste in India.

A batch digestion study of mixed vegetable market waste was carried out at 5% Total Solid (TS) concentration in a laboratory-scale digester of 10-l capacity. After 41 days, 0.15 m³ of biogas per kg of TS was observed with a maximum gas production rate of 650 ml/h on day 25. The Chemical Oxygen Demand (COD) reduction of vegetable waste slurry was found to be approximately 65%. Degradation of waste was also studied in a solid bed reactor of 100 l capacity at regular intervals. The COD of leachate obtained from solid bed digester ranged between 1500 mg/l and 25,000 mg/l.

Performance study for anaerobic digestion of municipal solid waste in a single phase reactor.

Anaerobic Digestion (AD) has been up to now essentially applied to wastewater. However, anaerobic treatment of organic solid waste fits well with the new requirements for waste management. A batch study of vegetable market waste composed at various solid concentrations was studied in a single phase anaerobic reactor. Prior to this, studies were also carried out in aspirator bottles of different capacity to select essential factors influencing the Single Stage High Solid (SSHS) approach with emphasis on C/N ratio. Initially, the maximum total solid concentration was optimised, which gives maximum biogas yield and at maximum total solid concentration, further experiments were carried out with varying C/N ratio to arrive at optimum C/N ratio leading to maximum biogas yield. This paper describes the performance of AD of municipal solid waste in a laboratory-scale reactor for varying solid concentration and C/N ratio.