Effluent characterization and different modes of reuse in agriculture-a model case study

High-quality waters are steadily retreating worldwide. Discharge of industrial effluent in the environment again declines soil/water quality to a great extent. On the other hand, effluent reuse in agriculture could be a means to conserve natural resources by providing assured water supply for growing crops. But industrial effluents are highly variable in nature, containing a variety of substances, and all are not favorable for farming. Appraisal and developing modes of effluent reuse is therefore a prerequisite to enable its proper use in agriculture. Effluents of various industries were assessed and approaches for their use in farming were developed for a particular region in this study. As per availability of effluents, the same could be implemented in other water-scarce areas.

Effluents of 20 different industrial units were characterized by 24 attributes. Comparing these with corresponding irrigation water quality standards, the probability of their reuse was interpreted in the first approach. On the basis of relevant properties of major soil types dominated in a particular region, the soil-based usability of effluent was worked out in the second approach. By emphasizing the limitation of groundwater development where it went beyond 50% exploitation level, the land form and major soil type were then identified by applying a soil-based effluent reuse approach; the area-specific suitability of its use was perceived in the third approach.

On the basis of irrigation water quality standards, the irrigation potentials of paper mill, fermentation (breweries and distilleries), and sugar factory effluents were recognized. In a soil-based approach, the compatibility of effluent with soil type was marked with A (preferred) and B (moderately preferred) classes and, compiling their recurring presence, the unanimous preference for paper mill effluent followed by rubber goods manufacturing industries/marine shrimp processing units, fermentation, and sugar mills was noted. Usability of these was also evident from a groundwater exploitation status-based approach.

The approaches of assessing industrial effluents differing in compositions systematically reflected the ability and applicability of certain effluents in agriculture. The context-specific assessment of effluent offers options to compare effluent from a range of viewpoints and enhances its reasonability of use for growing crops.

Chemical characterization of various industrial effluents first disclosed their potential of reuse. The soil-properties-based compatibility of effluent focused their prospects of use and groundwater-exploitation-status-based portrayed its area of use in a specific region. Assessment of effluent through these enhances reliability and appropriateness of its reuse in agriculture.

Options of industrial effluent (prospective) reuse in agriculture provide ways to combat freshwater crisis without degrading environmental quality. It may be applied for assessing effluent before its reuse in several water-starved countries.