| Abstrakt: |
Concern about the discharge of untreated industrial wastewater as a threat to the ecosystem is seriously increasing every day. Part of these discharges are generated by the agri-food industries, which must consider purification for successful remediation of ecosystems. Effluents from dairy industries are among the agri-food wastes richest in organic matter. It constitutes a major source of pollution due to its richness in macroelements and microbial pollutants. This study focused on the treatment of raw dairy effluents (RDE) from a dairy unit located in Bechar (Southwestern Algeria) using two processes: the first, a biological process in a laboratory-scale batch culture through three bacterial strains, namely Bacillus subtilis, Pseudomonas aeruginosa, and E. coli, and the second, a chemical treatment by adding different concentrations of coagulants [Al2(SO4)3; FeCl3]. Pollution indicator parameters, namely BOD5, COD, and total nitrogen content (TKN) were monitored and compared with the control sample (RDE). The results obtained for the analyzed pollution parameters of dairy effluents (COD: 653mgO2/L; BOD5: 554,5mgO2/L; TKN: 57,2mg/L; and NO3 -: 80mg/L) exceed the thresholds set by national regulations and must be adjusted to ensure compliance with Algerian standards. The results of the biological treatment showed high purification efficiency compared to chemical treatment with an abatement rate of 84,84% for COD; 95,06% for BOD5; 87,76% for total nitrogen; and 67,62% for nitrate, and removal of bacterial indicators of pollution by 48-50% for fecal coliforms; and 34-40% for fecal streptococci at the outlet of the batch culture system, attributed to B. subtilis and P. aeruginosa strains making post-treatment dairy effluents more compliant with national discharge standards than E. coli by reducing pollution indicator parameters. While chemical treatment with coagulants were less favorable with relatively high COD and BOD values. These results confirm the advantage of biological processes, which are simple, economical, and respectful of the environment. Thus, the purified effluent can be reused on-site in the production process, namely cooling, washing, and even irrigation. [ABSTRACT FROM AUTHOR] |
