Enhancing water efficiency and wastewater treatment using sustainable technologies: A laboratory and pilot study for adhesive and leather chemicals production

Abstract

The current study was designed to obtain the maximum water efficiency using water conservation strategies and at-source effluent treatment leading it reusable in three manufacturing plants (P I, II and III) of a leather chemical industry. The best available techniques (BATs) for water conservation were applied which resulted in 28.1 % and 44.8 % reduction in water usage and effluent generation respectively. Laboratory and pilot-scale electrocoagulation (EC) as well as horizontal subsurface flow constructed wetlands (HSSF CWs) were applied for the final treatment of effluent. In the electrocoagulation method, the obtained removal efficiency of COD, TDS, TSS and conductivity was 93.58 %, 43.23 %, 55.48 % and 35.42 % at the laboratory and 92.84 %, 37.97 %, 53.57 % and 33.58 % at pilot-scale respectively for P I and P II effluent. Removal efficiency using electrocoagulation was very low (all below 35 %) for P III effluent because of presence of electrolytes in excess which disrupt the experiment. Therefore, HSSF CWs were applied as an alternative treatment method for P III. Removal efficiency of COD, TDS, TSS and conductivity of HSSF CWs was 95.48 %, 34.10 %, 53.07 % and 9.83 % at laboratory and 95.43 %, 37.59 %, 51.52 % and 8.65 % at pilot-scale respectively. Finally, the treated wastewater was reused in all manufacturing plants for non-process activities. It is concluded that curtailing water consumption significantly reduces the effluent generation which after at-source treatment through sustainable technologies can be reused to produce near zero liquid discharge (ZLD) from leather chemical industry.