Effect of coagulant in greywater treatment for reuse: selection of optimal coagulation condition using Analytic Hierarchy Process

Abstract

A B S T R A C TThe objective of the present study was to (i) examine the effect of the coagulants on greywater (GW) characteristics under variable pH conditions, (ii) assess the potential of treated GW for reuse, and (iii) select optimal coagulation condition (pH and optimum dose) using Analytic Hierarchy Process (AHP). The effect of coagulants (alum and lime) was studied under four different pH conditions (8.5, 7.5, 6.5 and 5.5). Multiple linear regression models were built with optimum coagulant dose (OD) vs. pH, turbidity removal and alkalinity consumed. R 2 values ranged from 0.771 to 0.852 in case of alum and from 0.778 to 0.949 in lime treatment. In alum treatment, turbidity removal was above 88%, biochemical oxygen demand removal was in the range 53-77%, and Escherichia coli removal was 95-99% under the pH conditions examined. It was observed that alum-treated GW satisfied most of the reuse standards for the discharge of effluents into land for irrigation and industrial cooling in India. Total eight alternatives were ranked using AHP, considering nine criteria/subcriteria. Using AHP, the optimal alternative selected was alum treatment at pH 5.5 with OD 204 mg/L and the worst was lime treatment at pH 8.5.

Application of rotary in-vessel composting and analytical hierarchy process for the selection of a suitable combination of flower waste

“…Karimi, Mehradadi, Hashemian, Bidhendi, and Moghaddam (2011) used AHP method for selecting the best water treatment process. Ghaitidak and Yadav (2014) used AHP method to check the effect of coagulant in greywater treatment and selected the best coagulant condition. At present, the use of multi-attribute decision method has not used to find the best trials of any method used for the preparation of compost.…”

An assessment of technological development and applications of decentralized water reuse: A critical review and conceptual framework

“…Although ferric chloride works in a wide range of pH, it is very corrosive in nature. On the other hand, alum (Al 2 [SO 4 ] 3 · 18H 2 O) removed up to 83% of TSS and 99% of E. coli in greywater at pH 7.5 (Ghaitidak & Yadav, 2015). Coagulants and flocculants are rarely used as a single‐treatment option and commonly paired with other treatment methods such as sedimentation, sand filtration or disinfection.…”

Effect of particle size on rotary drum composting of garden waste and their ranking using analytical hierarchy process

“…Since, varying attributes have varying dimensions, normalisation is done to make attributes dimensionless. In the present study, geometric mean method is used as it is easier to understand (Ghaitidak & Yadav, 2015). In this method, eigenvalues are determined easily reducing the inconsistencies in judgement (Sharma & Yadav, 2018a).…”