【作者】 李金成；

【导师】 郑西来；

【作者基本信息】 中国海洋大学 ， 环境工程， 2011， 博士

【摘要】 高锰地下水的广泛存在迫切需要除锰技术具有即用性和稳定性。本研究针对地下水生物除锰过程中滤料成熟期长、除锰效果不稳定的问题,在深入探讨生物除锰机理的基础上,制备了与生物锰氧化物同型的化学负载锰氧化物滤料对水中的锰离子进行吸附去除,再采用化学氧化剂代替生物作用对饱和的负载锰氧化物滤层进行氧化再生。以此为基础,构建了“化学负载锰氧化物滤层(SMOF)+二氧化氯氧化再生”的除锰新工艺。1.通过柱实验研究了接种对生物除锰滤料成熟期的影响,发现形成具有吸附能力的锰氧化物活性层是滤料成熟的关键,由此揭示了锰氧化物在生物除锰中的重要作用:(1)经过接种的滤料成熟期约为70天,而未接种的滤料在此期间却无法达到成熟。(2)接种情况下,吸附能力较强的锰砂只需要20天左右即可达到阶段成熟,而石英砂则需要30天以上。(3)对不接种滤料,通过投加二氧化氯可加快锰氧化物的形成。当二氧化氯投加量为0.5mg/L时,经过30h滤层的出水锰浓度就可稳定在0.05mg/L以下;当投加量为1mg/L时,达到相同去除率的时间可减少到10h。2.将生物除锰滤层(BMRF)灭菌后得到不含微生物的生物负载锰氧化物滤层(BMOF)。二者的对比试验揭示了生物除锰的另一关键过程,即:微生物的催化氧化作用能使锰氧化物的吸附能力得到再生。(1)滤速变化时,BMOF对锰的去除率会下降20%~35%;而BMRF虽然对锰的去除率也会在短时间内下降,但由于生物再生作用的存在,去除率能很快恢复到90%以上。(2)原水锰浓度的提高会使BMOF对锰的去除率快速下降为55.9%。,而BMRF对锰的平均去除率仍可以达到为93.2%;(3)BMOF除锰过程的最佳pH范围在6-7之间,而BMRF则在5-9之间。BMOF除锰过程可以用Yoon-Nelson动态模型进行模拟。3.采用化学法人工制备负载锰氧化物,电镜检测显示其与生物形成的负载锰氧化物具有相同的Birnessite型层状结构。XRD检测表明,这种锰氧化物属于无定形态。生物合成与化学合成锰氧化物负载滤料的负载量分别为4.56mgMn/g和4.62mgMn/g滤料,而后者的负载强度在酸性、碱性和中性条件下都明显好于前者。4.通过化学合成锰氧化物负载滤料(SMOF)的静态吸附研究,建立了SMOF除锰的吸附等温线和动力学方程,得出饱和吸附量为0.32mgMn/g滤料,表明锰氧化物对锰具有较强的吸附能力。热力学分析结果表明,该吸附是自发过程。吸附过程符合准二级动力学方程。5. SMOF对锰吸附的影响因素研究表明,SMOF最佳的除锰pH应大于5,初始锰浓度与出水锰浓度具有一定的线性相关性。水的硬度和Fe2+均对SMOF的除锰效果有干扰:当硬度由100mg/L增加到600mg/L时,锰去除率从83%下降到55%,而当Fe2+由0.5mg/L增加到3mg/L时,锰去除率由82%下降到63%。6. SMOF滤层除锰动态试验显示,初始锰浓度和滤速的增大,都会加快滤层除锰效果的下降。对吸附饱和的SMOF滤层可以采用二氧化氯作为氧化剂进行再生。当再生液浓度为2mg/L时,滤层的除锰能力可在10min得到完全恢复。采用每日再生的方式具有更加稳定的除锰效果。SMOF的动态模型也符合Yoon-Nelson模型,但与BMOF相比吸附容量较小。7.构建了“化学负载锰氧化物滤层+二氧化氯氧化再生”的除锰新工艺。工艺稳定性试验结果显示,在进水锰浓度为1-4mg/L,滤速从8m/h-15m/h变化的情况下,锰去除率保持了良好的稳定性。但进水锰浓度相对于滤速对出水水质影响更大。更多还原

【Abstract】 High content of manganese is widely presented in ground water which needs a technique to remove manganese with instant and steady effect. Filter maturation period is quite long during the process of biological removal of manganese and the removal efficiency is not steady. On the basis of exploring the mechanisms of biological removal of manganese from ground water, chemical method was used to coat manganese oxides on filter and the structure of this manganese oxides filter was the same as the biogenic ones. After adsorbing manganese from ground water, chemical oxide agent was used to regenerate saturated manganese oxides. Further more, a new technique named“chemical manganese oxides-coated filter + chlorine dioxide oxides regeneration”was developed.1. The influences of inoculation on filter maturation were studied. Results showed the formation of manganese oxides active layer was the key factor for filter maturation, and the importance of manganese oxides in biological removal of manganese was revealed. (1) Maturation period of filter was 70 days when inoculated but it could not reach maturation when no inoculum was added during this period. (2) Under inoculation circumstances, manganese sands would reach maturation in 20 days because of its higher adsorption ability, but quartz sands need more than 30 days. (3)Adding chlorine dioxide could accelerate the formation of manganese oxides for no inoculation filter. When the dosage of chlorine dioxide was 0.5mg/L, the manganese concentration in outflow was under 0.05mg/L in 30 h; when 1 mg/L chlorine dioxide was added, it would attain the same removal efficiency in 10 h.2. Sterilize the biological manganese removal filter(BMRF) to obtain the biological manganese oxidation filter(BMOF)with no bacteria. The comparison experiment revealed another key process in biological removal of manganese, i.e. the catalytic oxidation of microorganisms regenerated the manganese sorption ability. (1)The removal efficiency of manganese decreased 20~35% in BMOF when the velocity of filtration varied, but in BMRF the value recovered up to 90% after a short decrease. (2)The removal efficiency of manganese in BMOF decreased to 55.9% when the concentration of manganese in original water increased, but the average removal efficiency in BMRF attained 93.2%. (3)The optimal pH range for manganese removal in BMOF was between 6-7 while in BMRF the pH value was between 5-9. The manganese removal process in BMOF could be simulated by Yoon-Nelson model.3. Manganese oxides were made by chemical method, and electron microscopy analysis indicated they had the same Birnessite structure with biogenic manganese oxides. XRD analysis showed this kind of manganese oxides belonged to amorphous form. The load capacity of biological and chemical synthesized manganese oxides was 4.56 mgMn/g filter and 4.62mgMn/g filter respectively, and the intensity of load in latter oxides was much better when they were used in acid, alkaline and neutral environment.4. Adsorption isotherms and kinetic model of SMOF were established by static adsorption study, and the saturation adsorption capacity was 0.32 mgMn/g filter indicated manganese oxides have significant adsorption ability. Thermodynamics results showed the adsorption process was spontaneous. Adsorption process fitted pseudo-second order model.5. Influencing factor research of adsorbing manganese with SMOF indicated the optimal pH was higher than 5, and the manganese concentration in outflow was in linear correlation with the concentration in inflow. Hardness and Fe2+ in water disturbed manganese removal. When hardness of water increased from 100mg/L to 600mg/L, removal efficiency of manganese decreased from 83% to 55%; when Fe2+ concentration in water increased from 0.5mg/L to 3mg/L,removal efficiency of manganese decreased from 82% to 63%.6. Dynamic experiment of removal manganese by SMOF indicated the removal efficiency decreased with the increase of original manganese concentration and the filter rate. The saturated SMOF could be treated with chlorine dioxide to regenerate its adsorption ability. When chlorine dioxide was added in 2mg/L, the capacity of removal manganese could be fully recovered in 10 min. Regenerating everyday would bring about steady removal efficiency. The dynamic process of SMOF fitted Yoon-Nelson model, but the capacity of adsorption was lower than BMOF.7. New technique for removal manganese from ground water was proposed, i.e.“chemical manganese oxides-coated filter + chlorine dioxide oxides regeneration”. Results showed removal efficiency maintained stable when manganese concentration varied from 1-4mg/L and filter rate changed from 8-15m/h, but manganese concentration in inflow had more influence on outflow quality compared to filter rate. This new technique doesn’t need to experience a maturation period.更多还原