الفهرس | Only 14 pages are availabe for public view |
Abstract The increasing environmental awareness of the world community to provide proper and efficient engineering solutions to wastewater treatment as part of a global strategy to control the pollution is the motive to carry out researches on enhancement of treatment technologies and improving their performance. The membrane bioreactors (MBR) technology is among the most recent promising innovations for wastewater treatment which give very high treatment efficiency. This study was carried out to assess the feasibility of combination between intermittent UASB with submerged membrane bioreactors to develop two stages (UASBIMBRl) for the treatment of domestic wastewater (sewage). Two treatment systems were operated in parallel, two stages (UASBIMBRl) system and single stage (MBR2) system. The field experimental work was divided into different phases: First phase: investigation and assessment of the combination between the intermitted UASB under mesophilic (25°C) conditions and the MBR system in a two stage UASBIMBRI compared with the single stage MBR2 system. Second phase: to study the performance of the two stage UASBIMBRI system with comparison with single stage MBR2 system under high flux rates (40-50 Vm2/hr). Third phase: to study the performance of the MBRs under moderate flux rates (20-25 Vm2/hr). Fourth Phase: to study the effect of the shock organic load on the performance of the two stage UASBIMBR system.The performance of both MBRs systems were evaluated regarding the prolonged steady operation period, the steady operational flux rate the trend for TMP increase, the chemical cleaning frequency and clean flux recovery after cleaning steps, and also, the treatment efficiency. The proposed combined UASBIMBRI system improved the operation performance ofMBRI to achieve maximum water recovery, higher permeate flux accompanied by less biofouling and less need. for chemical cleaning of the membranes. According to the obtained results, the present study resulted in the following conclusions: • the two stage UASBIMBRI systems shows a very high removal efficiencies with respect to the biological oxygen demand (BODS), the total suspended solids (SS), and chemical oxygen demand (COD) rather than single stage . MBR2 system, i.e., the average effluent concentration of BODS was 4 mg/l with a removal ratio of 98.6 % and the effluent concentration of COD was 46 mgll with average removal ratio of 90 % and the suspended solids on the effluent were not detective «2 mg/l), under normal operation conditions. • The efficiencies achieved by the intermittent UASB during the whole study for CODcsF, CODcF, CODDF, and SS were 61%, 37%, 26%, and 51%, respectively. • Making use of the produced biogas according to the anaerobic degradation of the wastewater can overcome a high percent of the energy cost required by the MBRsystem. • The most appropriate concentration of the mixed liquor suspended solids for the MBR is range from 8 to 12 gil for good aerobic biodegradability and proper steady operation of the MBR system. • The steady operation period was in range from 2.75 to 3 times higher with MBRl(two stage UASBIMBR1) rather than single stage MBR2, and hence the cleaning frequency was less leading to increasing the life time for the membranes unit and decreasing the cost for the membranes. • The cleaning rate is reduced for the two stage UASBIMBRI system with 65% saving the chemical required and avoiding the bad effect of the used chemicals on the life time of the membrane units. The combined UASBIMBR.l system was capable to handle the high organic shock load achieving removal ratio for COD total equal to 92.3% compared with 62.3 |