A two-stage multi-attribute decision-making model for selecting appropriate locations of waste transfer stations in urban centers.

Selecting appropriate locations for municipal solid waste (MSW) management facilities, such as transfer stations, is an important issue in rapidly developing regions. Multiple alternatives and evaluation attributes need to be analyzed for finalizing the locations of these facilities. Multi-attribute decision-making (MADM) approaches are found to be very effective for ranking several potential locations and hence selecting the best among them based on the identified attributes. However, conventional MADM approaches fail to find the rankings of alternatives derived from all possible combinations of these potential locations. Therefore, this study presents a two-stage MADM model that also accounts for all possible combinations of locations. This study evaluates economical, environmental, social and technical attributes based on realistic conditions of the study area, i.e., Nashik city (India). The results provide the ranks of all possible combinations along with their probabilities of rank reversibility. The mean and standard deviation of the relative closeness are further evaluated for the top-ranking locations under distinct schemes. The present study will help stakeholders in finding suitable locations for MSW management facilities while considering economic, environmental, social and technical attributes.

A facility location model for municipal solid waste management system under uncertain environment.

In municipal solid waste management system, decision makers have to develop an insight into the processes namely, waste generation, collection, transportation, processing, and disposal methods. Many parameters (e.g., waste generation rate, functioning costs of facilities, transportation cost, and revenues) in this system are associated with uncertainties. Often, these uncertainties of parameters need to be modeled under a situation of data scarcity for generating probability distribution function or membership function for stochastic mathematical programming or fuzzy mathematical programming respectively, with only information of extreme variations. Moreover, if uncertainties are ignored, then the problems like insufficient capacities of waste management facilities or improper utilization of available funds may be raised. To tackle uncertainties of these parameters in a more efficient manner an algorithm, based on interval analysis, has been developed. This algorithm is applied to find optimal solutions for a facility location model, which is formulated to select economically best locations of transfer stations in a hypothetical urban center. Transfer stations are an integral part of contemporary municipal solid waste management systems, and economic siting of transfer stations ensures financial sustainability of this system. The model is written in a mathematical programming language AMPL with KNITRO as a solver. The developed model selects five economically best locations out of ten potential locations with an optimum overall cost of [394,836, 757,440] Rs.1 /day ([5906, 11,331] USD/day) approximately. Further, the requirement of uncertainty modeling is explained based on the results of sensitivity analysis.

Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash in a fungal stirred tank aerobic reactor.

Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash was studied in a fungal stirred tank aerobic reactor without dilution of wastewater. Aspergillus niger isolate IITB-V8 was used as the fungal inoculum. The main objectives of the study were to optimize the stirrer speed for achieving maximum decolourization and to determine the kinetic parameters. A mathematical model was developed to describe the batch culture kinetics. Volumetric oxygen transfer coefficient (k (L) a) was obtained using dynamic method. The maximum specific growth rate and growth yield of fungus were determined using Logistic equation and using Luedeking-Piret equation. 150 rpm was found to be optimum stirrer speed for overall decolourization of 87%. At the optimum stirrer speed, volumetric oxygen transfer coefficient (k (L) a) was 0.4957 min(-1) and the maximum specific growth rate of fungus was 0.224 h(-1). The values of yield coefficient (Y ( x/s)) and maintenance coefficient (m (s)) were found to be 0.48 g cells (g substrate)(-1) and 0.015 g substrate (g cells)(-1) h(-1).

Optimization of the parameters for decolourization by Aspergillus niger of anaerobically digested distillery spentwash pretreated with polyaluminium chloride.

Molasses spentwash from distilleries is characterized by high COD and colour. The fungal decolourization of anaerobically digested molasses spentwash requires significant dilution. In this study, decolourization by Aspergillus niger isolate IITB-V8 was performed on polyaluminium chloride (PAC) treated anaerobically digested spentwash without dilution of wastewater. Optimization of parameters was studied using statistical experimental designs. In the first step, Plackett-Burman design was used for screening the important parameters. Glucose was taken as the carbon source for the growth of A. niger. KH(2)PO(4) and pH were found to be the important factors affecting decolourization. In the second step, Box-Behnken design was used to determine the optimum level of each of the significant parameters. A second-order polynomial was determined by the multiple regression analysis of the experimental data. The optimum values for the important factors to achieve maximum decolourization of 68.4% were 5.5 g/L Glucose, 1.2 g/L KH(2)PO(4) and 5 pH. The determination coefficient (R(2)) was 0.9973, which ensures adequate credibility of the model. The total decolourization obtained after fungal treatment was 86.8% which indicates fungal decolourization after pretreatment with PAC is a viable option for the treatment of digested molasses spentwash.

A GIS based transportation model for solid waste disposal--a case study on Asansol municipality.

Uncontrolled growth of the urban population in developing countries in recent years has made solid waste management an important issue. Very often, a substantial amount of total expenditures is spent on the collection of solid waste by city authorities. Optimization of the routing system for collection and transport of solid waste thus constitutes an important component of an effective solid waste management system. This paper describes an attempt to design and develop an appropriate storage, collection and disposal plan for the Asansol Municipality Corporation (AMC) of West Bengal State (India). A GIS optimal routing model is proposed to determine the minimum cost/distance efficient collection paths for transporting the solid wastes to the landfill. The model uses information on population density, waste generation capacity, road network and the types of road, storage bins and collection vehicles, etc. The proposed model can be used as a decision support tool by municipal authorities for efficient management of the daily operations for transporting solid wastes, load balancing within vehicles, managing fuel consumption and generating work schedules for the workers and vehicles. The total cost of the proposed collection systems is estimated to be around 80 million rupees for the fixed cost of storage bins, collection vehicles and a sanitary landfill and around 8.4 million rupees for the annual operating cost of crews, vehicles and landfill maintenance. A substantial amount (25 million rupees/yr) is currently being spent by AMC on waste collection alone without any proper storage/collection system and sanitary landfill. Over a projected period of 15 yr, the overall savings is thus very significant.

Effect of different inorganic and organic compounds on sorption of 2,4-D and atrazine.

In this study, the effects of size of adsorbent, temperature, pH of solution, ionic strength, presence of inorganic substances such as calcium ion, magnesium ions, chloride ions, fertilizers and presence of organic substances such as dissolved organic matter, surfactant, other herbicides on sorption of 2,4-D and atrazine onto rubber granules were investigated. The removal efficiency was more for fine adsorbent particles. Temperature played an important role in sorption process. Temperature effect was endothermic for 2,4-D and exothermic for atrazine, respectively. The removals were maximum at pH 4 for 2,4-D and at pH 6 for atrazine. The presence of other herbicide (butachlor) reduced sorption capacity of rubber granules by approximately 10% for both 2,4-D and atrazine. All other factors had insignificant effect on sorption capacity. The mathematical expressions were developed for predicting the overall percentage removal of 2,4-D and atrazine on the basis of major four controlling factors viz. adsorbent size, temperature, pH and presence of other herbicide.

Development of fixed bed adsorber for abatement of endosulfan in aqueous media.

In this paper an attempt was made to develop and evaluate the performance of a fixed bed adsorber (FBR) column to remove endosulfan, an organochlorine pesticide from the water environment using wood charcoal as an adsorbent. The FBR column design parameters were evaluated using the column breakthrough data at different bed depths. The Bohert and Adams model was used with bed depth-service time (BDST) approach for the design of the adsorber. Similarity in service time values estimated from BDST approach and experimental curves revealed that BDST approach could be adapted for the design of this system. Desorption of the exhausted column with 10% methanol solution took lhr with maximum desorption occurring at 0.5 hrs with a maximum endosulfan concentration of 47 mg 1(-1). A laboratory column study for 3 successive cycles of operation (adsorption-desorption) revealed that the column could treat 47.27 bed volumes of endosulfan contaminated water up to breakthrough and 158.45 bed volumes up to exhaustion. It showed a promising performance with more than 89% of its original efficiency even after the 3rd cycle of operation. It dearly demonstrates adaptability of the present study in developing adsorber columns for rural areas.

Assessment of imidacloprid in Brassica environment.

Imidacloprid was applied as seed treatment (Gaucho 70 WS, 5 and 10 g ai kg(-1) seed) and foliar spray (Confidor 200 SL, 20 and 40 g ai ha(-1)) at 50% pod formation stage on mustard (Brassica campestris Linn.) to control mustard aphid, Lipaphis erysimi Kalt. It was detectable upto 82 and 96 days in plants after sowing from lower and higher doses of seed treatment. However, it dissipated faster and became nondetectable after 7 and 15 days of foliar treatments from lower and higher rates of application, respectively. The dissipation models yielded the rate constants of 0.0209 and 0.0230 and 0.0736 and 0.0779 day(-1) from seed and foliar treatment. The corresponding half-lives of 14.40 and 13.07 and 4.09 and 3.86 days were recorded. This suggested that the dissipation was independent of initial doses and followed a first order rate kinetics. The projected TMRC of imidacloprid from seed (0.136 and 0.225 mg person(-1) day(-1)) and foliar (0.069 and 0.1497 mg person(-1) day(-1)) treatments were found lower than the MPI (3.135 mg person(-1) day(-1)). At harvest mustard grains did not contain imidacloprid residues. The absence of imidacloprid in 0-10 and 10-20 cm soil layers indicated no leaching of insecticide. Therefore, imidacloprid treatments could be taken as safe for crop protection, consumption of leaves and environmental contamination point of view.

Methodology for management of endosulfan contaminated eluent.

Management of Endosulfan contaminated eluent (24 mg/l) resulting from a treatment process to remove Endosulfan from water with wood charcoal, was attempted using various methods viz. volatilisation, hydrolysis and sorption by viable cell bacteria with and without acclimatisation. Volatilisation failed in giving better result, as Endosulfan was not considerably volatile. It could achieve a removal efficiency of 1.4-2%. Hydrolysis resulted in 28.4% and 17.9% removal of Endosulfan in acidic and alkaline media, respectively. Viable cell bacteria (aerobic) without prior acclimatization showed efficiency of 89.7% and after prior acclimatisation showed 96% removal efficiency. Sorption by the acclimatized biomass was found a suitable method for the removal of Endosulfan at a concentration of 24 mg/l.

Adsorbent selection for endosulfan removal from water environment.

In the present study, an attempt was made to select a low cost adsorbing material for the removal of endosulfan [C,C'-(1,4,5,6,7,7-hexachloro-8,9,10- trinorborn-5-en-2,3-ylene)(dimethylsulphite)] from water. Various low cost adsorbents like wood charcoal, kimberlite tailings, silica, macro fungi sojar caju were tried with activated charcoal as reference material. The above materials were selected from various sources encompassing organic, inorganic, clayey, and biological sources. For the selection of suitable adsorbent for endosulfan uptake, maximum adsorption capacity (Qmax) was chosen as the parameter. Kinetic profiles of removal were generated for all the materials to assess the equilibrium time. Equilibrium studies were carried out for all materials to assess the adsorption equilibrium model that they followed. The model that gave the best correlation coefficient by linear regression analysis, was adopted for the calculation of Qmax of the corresponding adsorbent material. Using linearised forms of equilibrium models like Langmuir, BET, and Freundlich, maximum adsorptive capacities were determined. Activated charcoal showed the best adsorptive capacity with Qmax of 2.145 mg/g followed by wood charcoal 1.773 mg/g, sojar caju 1.575 mg/g, kimberlite tailings 0.8821 mg/g, and silica 0.3231 mg/g. Albeit activated charcoal gave better performance, it was not considered as a candidate material because of its high cost. Wood charcoal was the next best adsorbent with Qmax 1.773 mg/g. Therefore, wood charcoal was chosen as the best material for endosulfan removal. The study of physical and chemical characteristics of wood charcoal revealed that it is a potential adsorbent and can even be improved further.