Physicochemical and Microbial Caracteristics Performency in Wastewater Treated Under Aerobic Reactor

Problem statement: The current work study the efficiency of biological wastewater treatment by an aerobic reactor which could be used in small agglomerations. RBC reduced physicochemical and microbiological load of wastewater but values remain above Tunisian standard. Approach: Experiments were conducted on a sand filled PVC column fed with wastewater treated by Rotating Biological Contactor (RBC) at a pulsed rhythm of 8 sequences per day. For performances study process, physicochemical and bacterial analyses effluent at inlet and outlet of column were realized. Results: The results showed that through filter mass (D10 = 0.55 mm, D60 = 1.3 mm and coefficient uniformity = 2.36) 96% of suspended solids, 99% of NH₄ ⁺-N (during first phase), 92% of COD, 91% of BOD₅ and 46% of phosphorus are retained by surface filtration. The microbial abatement results is <1.6 Log units of indicators fecal contamination (fecal coliforms, fecal streptococci and E. coli). The microbial water quality is slightly higher than Tunisian standards. The removal of microbial indicators in the considered reactor depends on the depth of the filter and negatively correlated with NO₃ ^--N (r = -0.99, with E. coli at 3rd OPD). Conclusion/Recommendation: Results confirmed that the reactor tested is performed as an advanced treatment system for DBO, COD, SS, NH₄ ⁺-N and NO₃ ^--N. Despite that 96% of SS efficiency reduction, clogging is not achieved quickly that due to biofilm detachment phenomena. The removal of microbial indicators in the considered reactor depends on the depth of the filter and negatively correlated with NO₃ ^--N. Disinfection performances for the considered reactor reduce microbial load, however chlore, ozone or UV disinfection should be considered.