Reclamation of water from dairy wastewater using membrane bioreactor (MBR)-Membrane filtration processes

In India, there are around 400 dairy plants in operation. Dairy wastewater is characterized by high organic load and suspended solids. The various treatment schemes (e.g. microbial fuel cell, hydrothermal liquefaction & membrane distillation, algal bioreactor, chemical coagulation & membrane bioreactor (MBR), ultrafiltration and MBR) achieve 75-80% organic load removal. The present study aims to improve the water recovery with the complete removal of organic loads and total solids from dairy wastewater (DWW), so that the treated water could be reused in the industry. The study involved an integrated treatment system of MBR and membrane filtration processes. The MBR was inoculated with specific bacterial colony acclimatized with dairy wastewater. Two different types of treatment system (i) submerged flat sheet polyvinylidene fluoride (PVDF) membrane of 0.2-0.3 lm pore size, and (ii) ceramic membrane was used. The MBR-PVDF membrane resulted in the removal of 99.8% COD, 98% BOD, 40% total dissolved solids, 80% NH4-N, and 98.7% PO4. The MBR-ceramic membrane resulted in the removal of 88.8% COD, 90% BOD, 30% total dissolved solids, 75% NH4-N, and 98.7% PO4. Both the MBR's produced clear treated water with no turbidity. The results mentioned above were obtained after 10 weeks of continuous operations in each MBR. The water produced no foul smell even after storing it in plastic container for more than 3 months at room temperature. The microbial population was identified under microscope as gramnegative rod-shaped bacteria Staphylococcus. FTIR-ATR study shows protein and carbohydrate deposition on the membrane surface. Chemical cleaning produced better flux than physical cleaning of the membrane surface. To reuse the treated water, it was passed through Polyamide Vontron75GPD (ULP 181275) commercial membrane in a dead end-filtration unit. The process resulted into 88.5% reduction in conductivity at 20 bar, thereby reducing the conductivity to 1.1 mS/cm. The treated water could be reused in the dairy industry. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Sustainable Technologies in Water Treatment and Desalination; "Materials Science".