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The goal of this study was to optimize the coagulation-flocculation process in wastewater generated from the paper and pulp industry using a grey relational analysis (GRA)-based Taguchi method. Process parameters included types and doses of natural coagulants and coagulant aid, and pH. To track the efficiency of the treatment process, the following responses were chosen for optimization: chemical oxygen demand (COD), total dissolved solids (TDS) and turbidity ofwastewater, alone or in combination or all together. Analysis of variance showed that the type and dose of the coagulant aid were the most significant parameters, followed by pH and the dose of the coagulant; the type of coagulant used was found to be insignificant in the coagulation-flocculation process. Optimization of process parameters to achieve lower turbidity and greater removal of COD and TDS was verified in a separate confirmatory experiment, which showed improvements in COD and TDS removal and a decrease in turbidity of 8.2, 6.35 and 26.17%, respectively, with the application of the Taguchi method and GRA. [ABSTRACT FROM AUTHOR]

Most coastal cities use the ocean as a site of waste disposal where pollutant loading degrades the quality of coastal waters. Presently, the west coast of Mumbai receives partially treated effluent from wastewater treatment facilities through ocean outfalls and discharges into creeks as well as wastewater/sewage from various open drains and nallahs which affect the water quality of creek and coastal water. Therefore, the objective of this paper is to simulate and assess the hydrodynamic behaviour and water quality due to impact of sewage and wastewater discharges from the west coast of Mumbai. Hydrodynamics and water quality were simulated based on present conditions and validated by using measured tide, current data and observed DO, BOD and FC. Observed and simulated results indicated non compliance to standards in Malad, Mahim creeks and the impact zones of ocean outfalls. The developed model could be used for generating various conditions of hydrodynamics and water quality considering the improvement in wastewater collection systems, treatment levels and proper disposal for proper planning and management of creeks and coastal environment. [ABSTRACT FROM AUTHOR]

The quantity and quality of water available for irrigation is variable from place to place in India. There are regions where the farmers have no access to any surface water body, nor do they have any groundwater source yielding water of acceptable quality for irrigation. Insome of the coastal areas, neither surface water nor ground water ofacceptable quality may be available. In such areas, setting up an industry and transporting good quality surface water from long distances to the site may be useful for farmers in the adjacent areas; the treated wastewater from the industry may constitute a dependable sourcefor irrigation. This paper gives a brief account of some of these peculiar situations. Whatever the situation, it is necessary that the water used for irrigation is of an acceptable quality for the crop concerned, growing on the soil of the site. For a given crop, during itsgrowth cycle, it is essential that the concentration of the soil solution around the root zone with regard to dissolved solids and specific ions, does not exceed the tolerance limit for the crop. The tolerance limits for various crops are different, representing 8- to 10-fold variation. Soil type and meteorological parameters of the site, fora given irrigation scheduling, also govern as to what will be the maximum soil solution concentration during the growth cycle of the crop. For a given crop, given soil and prevailing climate, the quality ofirrigation water and management ultimately determine this maximum level. At a given place, the type of soil and meteorological parameterscannot be managed by human beings. The farmer can, however, exercisesome control on the quality of irrigation water by selecting an appropriate source or changing the quality by dilution and/or he can makecertain changes in the agronomic control and crop selection. In thispaper, an attempt has been made to describe a few more important irrigation water quality criteria which will be easy for the users to follow and ar [ABSTRACT FROM AUTHOR]