Microbial Bioconversion of Dairy Wastewater in Packed Bed Biofilm Reactor into Liquid Biofertilizer

Abstract

Dairy industries are highly polluting, energy and fresh water consuming installations. The present study aims to make dairy effluent treatment plant operation less time consuming with minimal energy consumption while generating a value added product. Analysis of the temporal and spatial variation in performance of a biofilm based plug flow reactor involved in the biotransformation of Dairy Waste Water (DWW) revealed ammonia (57.68 mg L^–1) rich liquid biofertilizer production within 4 h, with associated reduction of nitrate (70.77%), phosphate (36.44%), protein (62.87%), Biological Oxygen Demand (BOD) (26.38%) and Chemical Oxygen Demand (COD) (39.59%). The process was 4 times faster than the fastest existing process reported till date. The consortium showed a striking reduction in its doubling time from 78 min 56 sec (in suspension culture) to 17 min 10 sec (as biofilm) upon immobilization. It could produce 734.60 mg ammonia per kg of immobilization matrix from DWW. Metagenomic analysis revealed the robustness of the biofilm based biotreatment system. The novelty of this study is the innovative approach of rapid conversion of the waste from dairy industry into a value added product using microbes from geosphere in an energy efficient manner which would make dairy effluent treatment plant operation self-sustainable and eco-protective.

Keywords:

• Dairy wastewater
• biofilm
• liquid biofertilizer
• plug flow reactor
• biotransformation
• metagenomics

Acknowledgements

The authors acknowledge Gomati Cooperative Milk Producers' Union Ltd, Agartala, for permitting wastewater collection, Tripura University and Centre of Excellence in Environmental Technology and Management at the Maulana Abul Kalam Azad University of Technology, West Bengal for providing the computational facility and laboratory infrastructure for conducting the experiments. The authors acknowledge Prof. Lalit Mohan Gantayet, Former Distinguished Scientist of Bhabha Atomic Research Centre for designing the reactor used in the study.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by University Grants Commission- Department of Atomic Energy, Government of India under the CRS scheme [UGC-DAE-CSR-KC/CRS/19/TE07/1069/1085]; Biotechnology Industry Research Assistance Council, Government of India under the Biotechnology Ignition Grant [BIRAC/KIIT0200/BIG-10/17]; and Ministry of Education under the Frontier Area of Science and Technology scheme [F.No 5-1/2014-TS.VII dt 7th Aug 2014].