| Drinking source water pollution is more and more serious, so it is widely concerned that drinking water advanced treatment to biological activated carbon as core. Immobilization biological activated carbon (IBAC) technology by immobilizating artificial cultivated dominant bacteria on activated carbon takes significant advantages and it improves the removal efficiency of organic contaminations depending on the adsorption of ctivated carbon cooperating with biological degradation of dominant bacteria. For open system, IBAC produces the problem of stabilization destruction due to vulnerable impact such as water quality, quantity and environmental factors in practical application, and it limites its broad application in the water industry.Aimming at the raw water quality conditions of the north city, the paper researchs effectively maintaining the biological stability of dominant bacteria from the various key of impacting biological stability of dominant bacteria, the major researches include that optimizing immobilization conditions of dominant bacteria, growth characteristics of dominant bacteria on activated carbon, influence and control of activated carbon property and process conditions to biological stabilization and security control of dominant bacteria and it provides technical support for project application of IBAC.Repeatedly enhancing biological activity of dominant bacteria by different concentration gradient nutrition substrate, it takes biological activity of 300μg/mL as the indicated end-point. By ultrasonic pretreatment to evaluate the immobilization characters of dominant bacteria, the optimizing immobilization conditions are researched. The results show that the optimizing immobilization conditions of dominant bacteria include the contact time 30 min, immobilization manner of cycling 4 h, intermittent 2 h and repeating three times.The growth characteristics of dominant bacteria on activated carbon are monitored at the long-term pilot-scale test by PCR-DGGE and SEM. The results show that at start-up period, there is a quickly reducing process in biomass and biological activity for about a week, then the biomass and biological activity gradually maintain stability for biological activity of 200μg/mL above and biomass quantity class of 106CFU/(g carbon) and the dominant bacteria immobilize on activated carbon in the form of single bacterium and in the rough part of activated carbon surface with more porous; after a long-term operation, the bacteria kinds of IBAC surface increase from 8 at initial stages to 16 after one year with different leves of biomass, but the artificial immobilized dominant bacteria still hold the advantaged position in plentiful biofilm and mission-floc formed on the activated carbon surface, mostly single-layer distribution. The aboriginal bacteria in low volume invasive system lead biological activity decreases of dominant bacteria in long-term slow downward for nutritional competition, sharing competitive and losing of disadvantage bacteria. The biological activity of upper and lower activated carbon deceases from 11×10-3mg O2/(cm3·h) and 7.5×10-3mgO2/(cm3·h)at initial stages to 8×10-3mgO2/(cm3·h) and 6×10-3mgO2/(cm3·h) after 18 months respectively.The water purification effect and growth characteristics of dominant bacteria are systematically researched at the dynamic test by immobilization dominant bacteria on 5 different types of activated carbon and the effect of activated carbon properties to biological stability is analyzed with statistical analysis methods. The results showed that the performance indexes of activated carbon greatly impact on biological stability mainly include molasses, iodine,butane, pH, average particle size, effective particle size, uniformity coefficient, friction coefficient, intensity, and molasses is primary control index of greater than or equal 150mg/g at selecting activated carbon.The effect of process conditions to biological stability including ozone dosage, EBCT and backwashing condition is researched by pilot-scale tests. The results show that the optimizing IBAC process conditions include ozone dosage of about 2.34mg/L, EBCT of 20min, air-water backwash, air backwashing intensity of 10L/m2·s with backwashing time of 5min at summer and 3min at winter, water backwashing intensity of 1215L/m2·s with backwashing time of 810min. The enhanced removal organic pollutions by dominant bacteria are monitored in long-term and the results show that compared with BAC, IBAC improves removal rates of 15% above in UV254, CODMn and TOC respectively and 11.23% in THMFP. The IBAC effluence of toxic substances kinds and concentration has significantly decreases. Aimming at the bio-security of dominant bacteria in application the process, it has been researched from the bacterium toxicology tests, sand controlling various biological leak, effluence toxicology tests and other points and the results showed that the dominant bacteria has higher bio-security. Application of activated carbon iodine value and static test methods, the renewable role of dominant bacteria have been evaluated and the results show that the the life-time of activated carbon can be effectively extended by dominant bacteria. Before reaching adsorption saturation of activated carbon, IBAC may be extended at least 1 year and achieving true failure of activated carbon will need in more than 3 years.The IBAC process has distinct characteristics of stable treatment efficiency, simple operation and management, low-cost operation, so it will bring about significant promotion of the economic, social and environmental benefits.
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