Treatment of industrial wastewater in the sequential membrane bioreactor

The aim of presented study which was associated with modification of the various work cycle phases duration in the membrane bioreactor, was to reduce the concentration of phosphate phosphorus during the leachate co-treatment with dairy wastewater. The experimental set-up was comprised of the membrane bioreactor equipped with the immersed membrane module installed inside the reactor chamber, and the equalization tank. During the co-treatment experiment performance the excessive activated sludge was constantly removed from the membrane bioreactor in order to keep its concentration at 3.5 g/dm³. The load of the sludge with the contaminants was equal to 0.06 g COD/g d.m. d. The concentration of oxygen was equal to 3 mg/dm³. The share of the leachates in the co-treated mixture was equal to 10% vol. The membrane bioreactor worked as the sequential biological reactor, in two cycles per day. Duration of each phase was equal as follows: filling - 10 min - with concurrent mixing phase lasting for 4 h, aeration phase - 1 h, sedimentation - 30 min and removal from purified wastewater - 30 min. After 4 weeks under these conditions, the modification of the sequential membrane bioreactor's work cycle was made. The duration of particular phases was shortened and two phases of denitrification and nitrification were introduced. Work cycle phases were modified as follows: filling - 10 min - with concurrent mixing phase lasting for 3 h, aeration phase - 4 h, mixing phase - 1 h, aeration phase - 3 h, sedimentation - 30 min and removal from purified wastewater - 30 min. Based on research, it was found that the change in membrane bioreactors' work cycle affects the effectiveness of treated mixture. It was found that the applied modification of phases of the cycle of the MSBR did not affect the concentration of organic compounds and the no significant changes in the concentration of ammonium and nitrate nitrogen in the effluent from the bioreactor were observed, however, the total nitrogen removal efficiency increased by 50%. Alteration of MSBR reactor particular phases duration caused reduction of concentration of P-PO₄³ from 4.7 to 2.9 mg/dm³.