Development of Effective Microbial Consortia based liquid formulations for Secondary Treatment of Wastewater

Naturally occurring bacteria in wastewater have a significant potential for bioremediation,
making them valuable for biological wastewater treatment. The effectiveness of microbial
communities in breaking down pollutants depends on their diversity and metabolic
capabilities. Therefore, developing environmentally friendly, indigenous microbial
consortia is crucial for efficient wastewater treatment. In this study, 20 bacterial strains
were isolated from wastewater samples collected from the dairy industry, sugar industry,
and hostel sewage water in Pusa, Bihar. These isolates were screened for their ability to
degrade starch, protein, and fat, as well as their potential to reduce Biological Oxygen
Demand (BOD) and Chemical Oxygen Demand (COD). Among the 20 isolates, 18
exhibited starch degradation, 10 showed protein degradation, and 11 demonstrated fat
degradation. Notably, seven isolates (DS-13, DS-27, DS-57, DS-58, DS-67, DS-68, and
DS-72) exhibited all three degradation activities and were further analyzed for their
impact on BOD and COD reduction. Out of these seven isolates, three (DS-58, DS-67,
and DS-72) demonstrated the highest reductions in BOD and COD when inoculated into
autoclaved effluents from the dairy industry, sugar industry, and hostel sewage. In
contrast, the blank (un-autoclaved effluents without bacterial inoculation) recorded BOD
levels of 835 mg/L, 1035 mg/L, and 620 mg/L, and COD levels of 1680 mg/L, 2280
mg/L, and 1470 mg/L for the respective effluent sources. To enhance biodegradation
efficiency, these three bacterial isolates were combined into different formulations,
creating four distinct microbial consortia. Among them, consortium C4 (comprising DS-
58, DS-67, and DS-72) exhibited the highest biodegradation efficiency, with starch
degradation of 14 mm, protein degradation of 24 mm, and fat degradation of 18 mm.
Additionally, C4 significantly reduced BOD levels from 115 mg/L to 353 mg/L and COD
levels from 407 mg/L to 641 mg/L. These findings indicated that the formulated C4
consortium has strong potential for biological wastewater treatment by effectively
breaking down organic pollutants and reducing water pollution. Its application in
wastewater management can contribute to environmentally sustainable bioremediation
strategies.