Microbial Remediation of Dairy Industrial Wastewater Using Batch Mode Moving Bed Biofilm Reactor (MBBR)

El Bestawy, Ebtesam; Easa, Saadia M.; Freez, Dalia M. A.

doi:10.21608/eajbsg.2022.257766

Microbial Remediation of Dairy Industrial Wastewater Using Batch Mode Moving Bed Biofilm Reactor (MBBR)

Document Type : Original Article

Authors

¹ Department of Environmental Studies, Institute of Graduate Studies and Research, Alexandria University, 163 Horria Ave. El-Shatby, P.O. Box 832, Alexandria, Egypt.

² Department of Microbiology, Faculty of Science, Ain Shams University.

³ Department of Microbiology, Faculty of Science, Tanta University.

10.21608/eajbsg.2022.257766

Abstract

The purpose of the present study was to investigate the ability and efficiency of the biological treatment to reduce dairy wastewater pollutants by reaching acceptable limits for safe discharging using indigenous bacteria. Ten indigenous bacteria (DM1-DM10) were isolated from dairy wastewater effluent and screened for decontamination process for 7 days. Quality parameters including biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO) and total viable count of bacteria (TVCB) were determined before and after the bioassay and their removal efficiencies (REs) were calculated. The three most promising screened bacterial strains were molecularly identified and used as individual or mixed free-living cultures in a batch mode remediation assay. Results showed a general trend of increasing the REs of all parameters by all the tested bacteria with increasing the exposure time. Strains DM5 {Bacillus Cereus ATCC14579 (NR-114582.1)}, DM6 {(Bacillus Aerius 24 K (NR-118439.1)} and DM7 {Bacillus cereus ATCC14579 (NR-074540.1)} recorded the highest activity for removing the selective pollutants, while strains DM2, DM8 and DM10 recorded the lowest removal efficiency for the same parameters. Therefore, DM5, DM6 and DM7 were used as individual and mixed free-living cultures in a batch mode remediation process. Raw dairy wastewater contains a very high level of COD (7680 mg/l), BOD (2700 mg/l) and a high level of TSS (1923 mg/l) indicating high organic load and suspended particles.It also contained an intermediate level of TDS (1220 mg/l) and a low DO level (0.49 mg/l) due to high organic contents and high microbial oxidation demand. Bacillus cereus ATCC14579 (DM7) showed the highest removal efficiency of BOD (78.11), COD (88.66%) and TSS (70.10 %) from dairy wastewater. It also exhibited the highest increase in TDS (59.10 %) and DO (389.89%). However, the mixed culture showed the lowest removals for the included contaminants. Moreover, DM7 showed the highest biomass yield (growth stimulation) during the batch mode treatment bioassay where it possesses the highest ability to biodegrade and benefit from the organic pollutants in the dairy effluents for its growth among all tested strains. Results of the present study confirmed that DM7 {Bacillus cereus ATCC14579 (NR-074540.1)} is the most promising for either minimization or decontamination of pollution load (mostly organic) from the dairy wastewater.

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