Combining submerged membrane technology with anaerobic and ...

TMP (kPa)Combining UASB and MBR for the treatment of low-strength wastewater at environmental temperaturesThe low OLR applied to the MBR had a great impact on MLVSS concentration. Asmentioned before, temperature also played an important role in the membraneperformance. COD removal efficiency in the methanogenic reactor increased withtemperature, causing a diminution of the biodegradable COD supplied to the aerobic MBR,and, as a consequence, leading to a lower MLVSS. The beginning of period II coincidedwith the beginning of the springtime. Therefore, higher temperatures observed from periodII onwards provoked an improvement of COD removal in the methanogenic reactor andhence, a decrease in the OLR applied to the MBR (figure 4.2a). Therefore, the supply of aminimum OLR in the MBR was shown to be of prime importance in order to maintainMLVSS, and hence to control membrane fouling rate. In this sense, the proposed systemcould be modified in order to allow the feeding of a small fraction of the raw influent directlyinto the aerobic biofilm chamber, in order to assure a minimum biodegradable CODsupply, and thus maintain F/M ratio above 0.1 kgCOD·kgMLVSS -1·d -1 (Brepols, 2006;Judd, 2011), especially when operating at higher temperatures.12111098760 2 4 6 8 10 12Time (h)Figure 4.5. TMP profiles after a physical cleaning at 3.0 gMLVSS·L -1 () and 0.5gMLVSS·L -1 (•) during operating days 145 and 319, respectively.4.5. Conclusions The combination of UASB and aerobic MBR technologies in one single system oras a post-treatment, presented a good performance for the treatment of low-strengthwastewaters at ambient temperatures. Both proposed configurations presented an125