| The security of water supply has in face of challenges because of serious water pollution and the more restrictive standard of water quality. As a high-efficiently and stably advanced water treatment technology, Bio-Enhanced Activated Carbon(BEAC) is widely used in city water treatment plants. Different from carbons focusing on adsorption, carbons focusing on bio-enhancement should balance adsorption capacity and holding capacity for functional bacteria. Therefore, carbons focusing on bio-enhancement requires more reasonable distribution of pore structure. However, carbons commonly used in the drinking water treatment in China are almost microporous carbons. BEAC process established using microporous carbons still has some disadvantages. Narrow distribution of superficial and internal pore structure of microporous carbons are difficult to deal with natural organic matter and immobilization of functional bacteria. These advantages seriously affected the purification efficiency and service-life of carbons. Therefore, the development and performance evaluation of an innovative activated carbon tailored for biological enhancement have important theoretical meaning and project application value.In this paper, based on coal-based activated carbons which pore structure have been regulated by innovative procedure including oxidation and depth-activation processes, effects of pore structure regulation was identified in terms of physical and chemical properties, adsorption capacities and holding capacity for functio nal bacteria. An innovative activated carbon XHIT focusing on bio-enhancement(XHIT) was identified through the above research. Results suggested that meso- and micro-porous structures of XHIT was synchronously regulated by introducing oxidation and depth-activation process. Compared to microporous carbons focusing on adsorption, XHIT has synchronously well-developed mesoporous(0.7041 cm3/g), microporous(0.2616 cm3/g) and macroporous(0.153 cm3/g) structues. Mesoporous volume during 20.4-208.2 ? increased to 0.6848 cm3/g, it promoted adsorption capacities of XHIT. Adsorption values of iodine, methylene blue and humic acids of XHIT reached to 1110, 251 and 1.033 mg/g, respectively. After 24 hours of immobilization, biomass of functional microbes on XHIT increased by 45.84 % and 21.40 %, respectively, compared to commercial carbons ZJ15 and PS. Abundant oxygen containing functional groups on surface of XHIT was beneficial to biodegradation and bioactivities of functional bacteria.Based on small-scale and RSSCT-scale system, comparative research on performance evaluation of XHIT was conducted treating water from Songhua River. Cooperative effectiveness between adsorption and biodegradation of XHIT was also investigated in terms of total amount control of micro-pollutants. Results suggested that purification efficiencies achieved by XHIT in both BAC(C-XHIT) and BEAC(B-XHIT) process were superior to regular carbons(PS and ZJ15), especially for fulvic acid, humic acid, aromatic organic matter, alkanes, benzene and naphthalene. Research on cooperative effectiveness between adsorption and biodegradation shows that cumulative uptake of organic-pollutants represented by CODMn(QC) and overall proportion achieved by biodegradation in B-XHIT increased from 31674.72(33.40%) to 61364.53 mg·CODMn/kg·carbon(47.53 %) during KBV ranges of 39.50-96.06 m3·H2O/kg·carbon. Biomass and microbial community structure indicated that surface micro-environment and pore structure distribution of XHIT was much more beneficial to immobilization and proliferation of advantage function bacteria and natural bacteria that originate from source water.Through the rapidly breakthrough of small-scale operation system, evaluation methods and representative indexes of service life of XHIT were i nvestigated based on breakthrough of CODMn and variation characteristics of adsorption performance indicators. Results suggested that accumulated water can be treated by XHIT in C-XHIT(2st-KBVC-3.0) and B-XHIT(2st-KBVB-3.0) reached up to 75.20 and 96.06 m3·H2O/kg·carbon, respectively, when average values of CODMn of raw water was 3.28±0.47 mg/L. QC achieved by C-XHIT(2st-QCC-3.0) and B-XHIT(2st-QCB-3.0) reached up to 103875.2 and 129089.85 mg·CODMn/kg·carbon, respectively. Well nonlinear correlation between KBVC/B-1.5(QCC/B-1.5) and 2st-KBVC/B-3.0(2st-QCC/B-3.0) was identified. Both KBVC/B-1.5 and QCC/B-1.5 were identified as the representative indexes to evaluate service-life of carbons. Results suggested that service-life of carbons evaluated based on variation characteristics of adsorption performance indicators were less than 2st-KBVC-3.0 and 2st-KBVB-3.0. Recommended limited value of adsorption performance indicators were proposed in present study.Based on above research findings, relating to characterization, purification performance, cooperative effectiveness and service life of XHIT, fundamental performance evaluation index system of carbons focusing on bio-enhancement was propose in present study. And comprehensive quantitative indicators syste m was established and improved. Results suggested holding capacity for functional bacteria and cumulative uptake of organic-pollutants can be well-predicted by comprehensive quantitative indicators(CQI), which calculated from 12 indicators including pore structure distribution and adsorption performance by introducing of ideal mode carbon and weightiness of fundamental performance evaluation indicators. Economic index of water purification of carbons based on 2st-KBVC/B-3.0 and 2st-QCC/B-3.0 suggested that tons of water-treatment cost of XHIT decreased in cooperation with PS and ZJ15. At the same time, XHIT achieved higher cumulative uptake of organic-pollutants. Therefore, XHIT was a promising coal-based carbon tailored for bio-enhancement with higher performance-price ratio.Through studies above, effects of pore structure regulation on adsorption capacities and holding capacity for functional bacteria was identified. Evaluation methods relating to cooperative effectiveness and service-life was established based on total amount control of micro-pollutants and characteristics of adsorption performance indicators. And comprehensive quantitative indicators system of carbons focusing on bio-enhancement are established and improved. Research findings in present study can provide new material and theoretical-technical support to depth water treatment process using activated carbon. The research can provide a reliable theory base and reference for stable operation of BEAC process. |
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