Assessing the feasibility of a vertical double submerged membrane modules system for wastewater reclamation under different conditions

Nowadays, water is deteriorating for several reasons, such as an increase in wastewater that flows into rivers and the limitation of water resources. Therefore, we have concentrated our plans on securing water resources by reusing wastewater treatment effluent. In this study the reuse system was organized using a submerged membrane bioreactor (SMBR) consisting of an anoxic, select, and aerobic tank. Our plan to solve the problems mentioned above involved optimizing the operating hydraulic retention time (HRT), which was done by comparing the characteristics of water treatment for several HRTs. Also, the simple and vertical double membrane modules were analyzed to find more effective operating condition in SMBR. The Specific characteristics of the SMBR system were represented as follows. We could know below 10 mg/L of BOD, below 5 mg/L of COD, 0 mg/L of SS without changes of HRT, which was satisfied with the standard of reuse water. Optimized HRT was 2.3 h and by composing the vertical double membrane modules, air flow rate could be reduced by 28.5%, lower than that of the simple membrane module.

For water reuse of municipal wastewater the combined system, bio-reactor as the bio-treatment of Activated sludge system and submerged membrane module, creates the following results. The removal efficiencies of the SS, COD and BOD in the submerged membrane bio-reactor with the various HRTs were 100, 95 and 93% respectively. Also Turbidity, color and total coliforms were removed on the mode 4 condition, which was the shortest HRT to 0.49 NTU, below 20 degrees and not detected respectively. Therefore, it could be possible to meet the water reuse standards even though the shortest HRT of line I and line II was applied (Line I: 4.6 h; Line II: 2.3 h). The relationship between the COD, BOD volumetric loading rates and the effluent quality was investigated. The COD, BOD volumetric loading rates highly ranged 0.061–0.48 kg. COD m3/day, 0.28–1.5 kg. BOD m3/day respectively. But the average removal efficiencies of BOD and COD were 95 and 93% with the mode 4 condition which was the shortest HRT. It indicates that the organic loading is not the factor affected to the effluent quality, because the SMBR system is maintained over 10,000 mg/L of MLSS concentration which can reduce the loading impact from the inflow organic loading. To evaluate the economic advantage of the SMBR, two different membrane module configurations were also investigated. The vertical double membrane modules configuration (line II) could operate with only increasing 1.5 times aeration amounts compared to the simple membrane module configuration (line I). At that time the A/L ratios were 20.7, 14.8 respectively. The A/L ration of line II decreased to 28.5%. As the results the vertical double membrane modules configuration can produce twice the quantity of water with the same bioreactor volume of the simple membrane module. It is the economic advantage of this system. Therefore, it proves that the vertical double membrane modules configuration is very effective configuration of the SMBR system.