Development of kinetic models for organic and nutrient removal in biofilm photobioreactor for treatment of domestic wastewater

In this study, four biofilm photobioreactors (BPBRs) were developed for treating septic tank effluent under different hydraulic retention times (HRTs), organic (OLR), nitrogen (NLR) and phosphorus (PLR) loading rates and light intensities. The HRT of 6 days, OLR of 390 mg COD/(m(2).d), NLR of 90 mg N/(m(2).d), PLR of 6.1 mg P/(m(2).d) and light intensity of 150 mu mol/(m(2).s) were found to be optimum operating conditions for the BPBRs, resulting in the COD, TN and TP removal efficiencies of 85, 87 and 84 %, respectively, with the effluent quality meeting the discharge standards of Thailand and the ISO 30500. Moreover, the HRTs, OLRs, NLR, PLRs, light intensities as well as daily light integral (DLI) were observed to significantly affect treatment performance and biomass productivity of the BPBRs. Hence, the kinetic models involving these operating parameters including temperature were developed for COD, TN and TP removal in the BPBR system and validated satisfactorily with the data obtained from some previous studies. Application of the developed kinetic models in the design and operation of the BPBR system treating a domestic wastewater was also demonstrated. (C) 2021 Elsevier B.V. All rights reserved.