Cost effective bioprocess for actual dye manufacturing industrial wastewater using statistical tool

Abstract

Dye contaminated wastewater is a cause of concern in textile and dyeing industry. By law, it is now mandatory to treat colour along with chemical oxygen demand (COD) from the effluent to required standards before discharging the same. In this context, bioremediation of textile effluent by bacterial consortium has gained considerable attention as it is relatively cost-effective and eco-friendly. Here, we propose a novel bacterial consortium consisting of <i>Bacillus </i> sp., <i>Proteus mirabilis</i>, <i>Alcaligenes faecalis</i> and <i>Bacillus cereus</i>, capable of removing 70% ADMI and 65% COD of effluent in mineral medium with 100% removal of heavy metals present in the effluent. Medium formulation by response surface methodology (RSM) method resulted in 89% COD reduction and 84% ADMI reduction from the SSDM effluent. The consortium was capable for degradation of SSDM effluent having as high as 21000 ADMI colour value. Analysis of untreated and treated SSDM effluent on UV-Vis spectroscopy and HPLC confirmed the mineralization of SSDM effluent. Induction of intracellular azo reductase (838%, 780%), NADH-DCIP reductase (288%, 216%) in addition to extracellular tyrosinase (102%, 309%) in F-MSMUJ and MSMYG medium, respectively indicates the vital role of oxido-reductive enzymes in the mineralization process. Single cell gel electrophoresis technique using <i>Allium cepa</i> showed decrease in tail length of comet for treated effluent compared to the untreated. Complete germination (100%) of plant seeds, <i>Vigna radiata</i> and <i>Trigonella foenum-graecum</i>, was achieved after treatment by the consortium in contrast to a meagre 20 and 30% germination of the respective plants in case of untreated effluent. Batch and fed batch treatment of SSDM effluent showed significant tolerance of consortium at high effluent load.