Atul N. Vaidya

Bioreactors for treatment of VOCs and odours – A review

Volatile organic compounds (VOCs) and odorous compounds discharged into the environment create ecological and health hazards. In the recent past, biological waste air treatment processes using bioreactors have gained popularity in control of VOCs and odour, since they offer a cost effective and environment friendly alternative to conventional air pollution control technologies. This review provides an overview of the various bioreactors that are used in VOC and odour abatement, along with details on their configuration and design, mechanism of operation, insights into the microbial biodegradation process and future R&D needs in this area.

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.

A roadmap for development of sustainable E-waste management system in India

The problem of E-waste has forced Environmental agencies of many countries to innovate, develop and adopt environmentally sound options and strategies for E-waste management, with a view to mitigate and control the ever growing threat of E-waste to the environment and human health. E-waste management is given the top priority in many developed countries, but in rapid developing countries like India, it is difficult to completely adopt or replicate the E-waste management system in developed countries due to many country specific issues viz. socio-economic conditions, lack of infrastructure, absence of appropriate legislations for E-waste, approach and commitments of the concerned, etc. This paper presents a review and assessment of the E-waste management system of developed as well as developing countries with a special emphasis on Switzerland, which is the first country in the world to have established and implemented a formal E-waste management system and has recycled 11kg/capita of WEEE against the target of 4kg/capita set by EU. And based on the discussions of various approaches, laws, legislations, practices of different countries, a road map for the development of sustainable and effective E-waste management system in India for ensuring environment, as well as, occupational safety and health, is proposed.

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.

Kinetics of biosurfactant production by Pseudomonas aeruginosa strain BS2 from industrial wastes

SummaryBatch kinetic studies were carried out on rhamnolipid biosurfactant production from synthetic medium, industrial wastes viz. distillery and whey waste as substrates. The results indicated that the specific growth rates (μ max) and specific product formation rates (V max) from both the wastes are comparatively better than the synthetic medium, revealing that both the industrial wastes (distillery and whey) can be successfully utilized as substrates for biosurfactant production.

Pretreatment of banana agricultural waste for bio-ethanol production: individual and interactive effects of acid and alkali pretreatments with autoclaving, microwave heating and ultrasonication.

Banana agricultural waste is one of the potential lignocellulosic substrates which are mostly un-utilized but sufficiently available in many parts of the world. In the present study, suitability of banana waste for biofuel production with respect to pretreatment and reducing sugar yield was assessed. The effectiveness of both acid and alkali pretreatments along with autoclaving, microwave heating and ultrasonication on different morphological parts of banana (BMPs) was studied. The data were statistically analyzed using ANOVA and numerical point prediction tool of MINITAB RELEASE 14. Accordingly, the optimum cumulative conditions for maximum recovery of reducing sugar through acid pretreatment are: leaf (LF) as the substrate with 25 min of reaction time and 180°C of reaction temperature using microwave. Whereas, the optimum conditions for alkaline pretreatments are: pith (PH) as the substrate with 51 min of reaction time and 50°C of reaction temperature using ultrasonication (US).

Biotreatment of Oil-Bearing Coke-Oven Wastewater in Fixed-Film Reactor: A Viable Alternative to Activated Sludge Process

Coke-oven wastewater is produced in the integrated steel plants at coke-oven gas-cleaning operations. It is laden with phenol, cyanide, thiocyanate, and oil. Although the activated sludge process is widely practiced in the biological treatment of coke-oven wastewater, it was observed during field visits that oil contamination and poor sludge settleability had resulted in poor maintenance of the activated sludge process. These problems can be minimized by the use of fixed-film systems such as trickling filters; however, availability of a microbial consortium, which would sustain oil contamination, was a major constraint. Research endeavor at this Institute has resulted in the development of such a microbial consortium, and the same was applied on a bench-scale fixed-film system such as a trickling filter, for the treatment of coke-oven wastewater. The unit was set up in the steel industry, and fresh coke-oven wastewater was treated over a period of 45 days. The results indicated that phenol and oil were si...

Biomethanation of vegetable market waste in an anaerobic baffled reactor: Effect of effluent recirculation and carbon mass balance analysis.

In the present study, feasibility of biomethanation of vegetable market waste in a 4-chambered anaerobic baffled reactor (ABR) was investigated at 30d hydraulic retention time and organic loading rate of 0.5gVS/L/d for one year. Indicators of process stability viz., butyrate/acetate and propionate/acetate ratios were consistent with phase separation in the different chambers, which remained unaltered even during recirculation of effluent. Chemical oxygen demand (COD) and volatile solids (VS) removal efficiencies were observed to be consistently high (above 90%). Corresponding biogas and methane yields of 0.7-0.8L/g VS added/d and 0.42-52L/g VS added/d respectively were among the highest reported in case of AD of vegetable waste in an ABR. Process efficiency of the ABR for vegetable waste methanation, which is indicated by carbon recovery factor showed that, nearly 96.7% of the input carbon considered for mass balance was accounted for in the product.

Effect of organic loading rate during anaerobic digestion of municipal solid waste

The effect of chemical oxygen demand (COD) and volatile solids (VS) on subsequent methane (CH4) production during anaerobic digestion (AD) of organic fraction of municipal solid waste (OFMSW) was studied in a laboratory-scale digester. The experiment was performed in 2L anaerobic digester under different experimental conditions using different input mass co-digested with inoculum and organic loading rate (OLR) for 27days at 38±2°C. Three digesters (digesters 1, 2 and 3) were operated at initial loading of 5.1, 10.4 and 15.2g/L CODS per batch which were reduced to 77.9% and 84.2%, respectively. Cumulative biogas productions were 9.3, 10.7 and 17.7L in which CH4 yields were 84.3, 101.0 and 168.4mL/gVS removal in digesters 1, 2, and 3, respectively. The observed COD removal was found to be influenced on variation in CH4 production. Co-efficient of determination (R(2)) was 0.67 and 0.74 in digesters 1 and 2, respectively.

Treatment of mixtures of toluene and n-propanol vapours in a compost-woodchip-based biofilter.

The present work describes the biofiltration of mixture of n-propanol (as a model hydrophilic volatile organic compound (VOC)) and toluene (as a model hydrophobic VOC) in a biofilter packed with a compost–woodchip mixture. Initially, the biofilter was fed with toluene vapours at loadings up to 175 g m−3 h−1 and removal efficiencies of 70%–99% were observed. The biofilter performance when removing mixtures of toluene and n-propanol reached elimination capacities of up to 67 gtoluene m−3 h−1 and 85 g n− propanol m−3 h−1 with removal efficiencies of 70%–100% for toluene and essentially 100% for n-propanol. The presence of high n-propanol loading negatively affected the toluene removal; however, n-propanol removal was not affected by the presence of toluene and was effectively removed in the biofilter despite high toluene loadings. A model for toluene and n-propanol biofiltration could predict the cross-inhibition effect of n-propanol on toluene removal.