ORIGINAL PAPER Utilization of electrocoagulation-treated spent wash sludge in making building blocks P. Sharma 1 • H. Joshi 1 Received: 26 August 2014 / Revised: 6 April 2015 / Accepted: 5 July 2015 / Published online: 28 July 2015 Ó Islamic Azad University (IAU) 2015 Abstract Minimization, utilization and disposal of industrial waste are very important from the environmental esthetic point of view. Sludge generated during the treat- ment of distillery spent wash by electrocoagulation process is highly complex in nature and requires proper disposal. In this context, the present study was conducted to employ the electrocoagulation-generated sludge as a partial replace- ment of cement while manufacturing the non-construc- tional building blocks. Various physiochemical and thermo-gravimetric characterization studies have been carried out on electrocoagulation-generated sludge and cement. Mortar specimens with different proportions of sludge ranging from 0 to 15 % by weight of cement were tested for density, compressive strength and leachability of heavy metals by standard method. Results from the anal- ysis showed that the cement-based solidification of EC sludge reduces the heavy metal concentration in the lea- chate from cement–sludge mortars compared to the EC sludge alone. Reduction in the compressive strength of mortar with 7.5 % substitution of cement by EC sludge was \ 5 % against the control mortar (without sludge), there- after the reduction was substantial. The optimum percent- age of sludge that can replace the cement with marginal change in the physiochemical properties is found to be 7.5. This can be used in the manufacturing of the non-con- structional building material within the industry for their different types of usages such as paving, pot making and fencing of garden without affecting the environment. Keywords Electrocoagulation sludge Á Compressive strength Á Leachability Á Thermal degradation Introduction Distilleries are among 17 most polluting industries in India (CPCB 2001–2002). Usually about 8–15 l of wastewater is generated for every liter of alcohol produced by the molasses-based distilleries called ‘‘spent wash.’’ The spent wash is characterized by extremely high chemical oxygen demand, biological oxygen demand, suspended solids, inorganic solids, color content and acidic pH (Shin et al. 1992; Saha et al. 2005). For industries using large quantities of water such as distilleries, it is essential to treat and reuse their wastewater for achieving zero discharge. Electroco- agulation (EC) technology is one of the promising tech- nologies for the treatment of this high-strength industrial wastewater. An important issue associated with the EC treatment is the generation of large volume of sludge that is semisolid and bulky. EC sludge generated is very complex in nature having organic and inorganic matter; oil and grease; toxic heavy and trace metals (Rahman et al. 2012). It also contains hydroxide of metals used as sacrificial anode dissociated during wastewater treatment (Golder et al. 2006). These metal hydroxides are hazardous in nature and cannot be discharged as such to water bodies. This residual solid waste is considered as a nuisance to the distilleries as well as to the environment because of various handling and management issues (Weng et al. 2003; Balasubramania et al. 2006; Baskar et al. 2006). Sludge treatment and dis- posal are an expensive operation and has negative impact on environment. The land application of metal containing sludge leads to soil and ground water contamination (Thomson et al. 2009). Leaching of heavy metals (e.g., Cd, & P. Sharma jangra.pinki@gmail.com 1 Department of Hydrology, Indian Institute of Technology Roorkee, Roorkee 247667, India 123 Int. J. Environ. Sci. Technol. (2016) 13:349–358 DOI 10.1007/s13762-015-0845-7