Grey water treatment in upflow anaerobic sludge blanket (UASB) reactor at different temperatures

摘要

The treatment of grey water in two upflow anaerobic sludge blanket (UASB) reactors, operated atndifferent hydraulic retention times (HRTs) and temperatures, was investigated. The first reactorn(UASB-A) was operated at ambient temperature (14–25 WC) and HRT of 20, 12 and 8 h, while thensecond reactor (UASB-30) was operated at controlled temperature of 30 WC and HRT of 16, 10 and 6 h.nThe two reactors were fed with grey water from ‘Flintenbreite’ settlement in Luebeck, Germany.nWhen the grey water was treated in the UASB reactor at 30 WC, total chemical oxygen demand (CODt)nremoval of 52–64% was achieved at HRT between 6 and 16 h, while at lower temperature lowernremoval (31–41%) was obtained at HRT between 8 and 20 h. Total nitrogen and phosphorous removalnin the UASB reactors were limited (22–36 and 10–24%, respectively) at all operational conditions. Thenresults showed that at increasing temperature or decreasing HRT of the reactors, maximum specificnmethanogenic activity of the sludge in the reactors improved. As the UASB reactor showed ansignificantly higher COD removal (31–64%) than the septic tank (11–14%) even at low temperature, itnis recommended to use UASB reactor instead of septic tank (the most common system) for greynwater pre-treatment. Based on the achieved results and due to high peak flow factor, a HRT betweenn8 and 12 h can be considered the suitable HRT for the UASB reactor treating grey water atntemperature 20–30 WC, while a HRT of 12–24 h can be applied at temperature lower than 20 WC.