Effect of low temperature thermochemical pretreatment on sludge reduction potential of membrane bioreactor treating primary treated dairy wastewater

Abstract

In this present study, an aerobic submerged membrane bioreactor (MBR) was used to study the effect of thermochemical pretreatment on the efficiency of sludge reduction. For this purpose, two MBRs were fabricated. Between the two MBRs, one acted as a control reactor (CMBR) and the other acted as an experimental reactor (EMBR). The MBRs were operated with a mixed liquor suspended solids (MLSS) concentration in the range of 6,800-7,200 mg/L for a period of 160 days. In the EMBR, part of the MLSS was withdrawn at a ratio of 1% of Q and was pretreated by low temperature thermochemical treatment. The sludge pretreatment was carried out at 60 W C and an alkali dosage in the range of 0.49 to 0.56 mg NaOH/mg MLSS. During the pretreatment, 42% of COD solubilization and 22% of SS reduction were observed. The pretreated sludge was returned to the reactor for further degradation where it was found to be 42% reduced. During the 160 days of reactor operation, both of the MBRs maintained a relatively constant transmembrane pressure. The sludge digestion does not have any impact on the COD removal efficiency of the reactor.

Effect of alkaline and ozone pretreatment on sludge reduction potential of a membrane bioreactor treating high-strength domestic wastewater

“…However, the inorganic fraction of the degraded cells did not accumulate in the EMBR and presumably permeated through the membrane as ionic species. Similar to our study, while working on integration of sludge disintegration system in A 2 O treating domestic wastewater, Banu et al [4] have reported, that there is no change in volatile fraction of the mixed liquor before and after the sludge pretreatment.…”

“…In the present study, sludge reduction experiments were carried out at a fixed MLSS range of 7,000-7,200 mg/L. It was clear that the sludge reduction could be increased by operating the MBR at relatively high MLSS concentrations [4]. At high MLSS concentrations, the sludge yield was comparatively lower than at low MLSS concentrations, and the designed pretreatment Q also carried more solids for disintegration.…”

“…(2014) [1][2][3][4][5][6][7][8] www.deswater.com doi: 10.1080/19443994.2014.923335 growing nitrifier in the reactor. In addition, MBR does not rely on sludge settling characteristics, which is a common factor responsible for failure of activated sludge treatment plant.…”

“…Most of these features result from the possibility of uncoupling the SRT and the hydraulic retention time (HRT), which reflects the basic concept that solid-liquid (sludge/effluent) separation is provided through a highly efficient membrane filtration rather than the traditional gravity settling [2]. The treatment and disposal of excess sludge produced during aerobic treatment accounts for about 50-60% of the total cost of wastewater treatment [3,4]. Therefore, sludge reduction is very important for economical treatment.…”

“…It was basically composed of a mixed carbon source, macro-nutrients (N and P), an alkalinity control (NaHCO 3 ), and a microelement solution [23]. The composition contained (per L) 800 mg glucose, 200 mg NH 4 …”