A Pilot-scale Study Of Hybrid Membrane Bioreactor Applied To Campus Wastewater Treatment

Membrane bioreactor(MBR) technique, as the best practical sewage treatment technology in the 21 st century, has significant advantages in sewage collection and disposal, resulting in positive treatment outcomes. However, problems including membrane flux decline, frequent cleaning of membrane element and short service life of membrane module, caused by membrane fouling, have restricted MBR application in process stability and economical aspects. In this article, normal campus sewage was treated and researched by anoxic-oxic hybrid membrane bioreactor(A/O-HMBR), which is anoxic/oxic membrane bioreactor(A/O-MBR) added with different packing, so that the optimizing function on A/O-MBR comprehensive treatment effect and the contribution function on retarding membrane fouling by packing were investigated and the different effects from different packing were compared, which helped select a better A/O-HMBR technique.Firstly, A/O-MBR and A/O-HMBR with two different packing had been operated continuously and steadily for 30 days under a better operating condition(IR is 200%, HRT is 8h, aeration intensity is 20 m3/h). The results showed that the removal rate of CODCr, NH3-N, TN and TP from A/O-HMBR from combined packing were 0.56%, 1.5%, 11.23% and 7.84% higher than A/O-MBR. The results of A/O-HMBR from suspended packing were 0.65%, 0.9%, 8.16% and 5.7%. Also, the comprehensive treatment effect of combined packing was slightly better than that of suspended packing. The affinity interaction on microorganism from combined packing’s soft fiber bundles was better than that of suspended packing, of which the surface was relatively smooth, thus having better effect on organic pollutants’ removal. It was the effluent quality of A/O-HMBR system meeting the reclaimed water reuse standard that illustrated A/O-HMBR could be applied in sewage treatment of urban landscaping.Secondly, when using TMP to represent two A/O-HMBR systems’ membrane fouling condition, this experiment had undergone initial stable development phase, mid-term slow growth phase and late rapid growth phase. The first two phases of combined packing membrane module were longer than those of suspended packing one and the polluting rate was relatively lower. After filtration resistance measurement,it was found that the internal resistance force(Rirf) caused by absorbing blocking pollutant in membrane duct was the main factor leading to membrane fouling and the percentage of Rirf from combined packing module was 4.4% lower than that of suspended packing module. After measuring membrane module surface EPS and packing surface EPS, the average module surface EPS of combined packing module was 1.4 mg/gMLSS lower than that of suspended packing module and the packing surface EPS of combined one was 15mg/gMLSS higher. The main reason was that the suspension method and surface microorganism living condition could ease suspended particle deposition on surface and reduce cake layer deposition fouling. Also, suspended packing could hardly remain complete fluidized state and contain less surface microorganism, thus having less membrane fouling inhibiting effect. Therefore, combined packing A/O-HMBR system was better than suspended packing one in terms of reducing membrane fouling. Also, the two A/O-HMBR surface EPSs were 7.8 mg/gMLSS and 6.4mg/gMLSS respectively lower than that of A/O-MBR systems, which meant surface packing could slow down membrane fouling process. After cleaning membrane module by water, acid and alkali, pure alkali cleaning contributed the most with recovery rate being 50% or so. In addition, a series of operation measures in this experiment had furthest slowed down membrane fouling process.Finally, economic analysis was conducted in terms of A/O-HMBR system engineering construction fee, operation and management fee and economic benefit. It turned out that membrane purchase cost and replacement fee took the highest proportion in total cost. Adding packing could reduce membrane depreciation cost and lower membrane cleaning frequency. In conclusion, A/O-HMBR system with packing has practical meaning to reduce fouling and operating cost.