| The alkali-minimization wastewater, produced by the alkali deweighting process, is difficult treatment in the textile printing and dyeing wastewater, with high p H and CODCr, variable to water quality and quantity, and poor biochemical characteristics. In the process, the alkali-minimization wastewater is mixed with the textile printing and dyeing wastewater to reduce the high p H and CODCr. But difficult biodegradation materials, such as terephthalic acid sodium salt, oligomer, etc., bring greater challenge for dealing with wastewater.This topic is that the SCAR deals with alkali-minimization wastewater, to study on the start-up, key factors, and the influence of reflux ratio for wastewater treatment and anaerobic granular sludge. The purpose of this subject is to study degradation characteristics for main pollutants of alkali-minimization wastewater in SCAR, and to provide theoretical reference for dealing with alkali-minimization wastewater.The experimental results showed as follows:（1）SCAR was inoculated with anaerobic granular sludge to treat artificial alkali-minimization wastewater, with the temperature of 3335℃, R=0.5, p H=6.87.2 and HRT=24h. After continuously running 60 days for six stages, the results showed that the average removal rate of CODCr was up to 42%. The VFA concentration was stable at around 300 mg/L and had no phenomenon of accumulation in the system.The reactor appeared obvious function of degenerating pollutants in the vertical direction.During the start-up time, the concentration of dehydrogenase in the second outlet of the reactor was the highest with 5.16 mg/（g VSS·h） and in the third outlet of the reactor was the slowest. Coenzyme F420 showed slow growth at first and then remained stable, in which the highest concentration was 0.0167μmol/g VSS. SCAR exhibited differentremoval rules inboth CODCrand UV254foralkali-minimizationwastewater withdifferentmolecularweightorganics.SCAR cannot degrade benzene series completely in the laboratory’s condition.（2） After completion of the start-up, the SCARwas designed for orthogonal experiment. The experiment was respectively changed of HRT（24, 12,8 h）, wastewater alkalinity（120, 500, 1000 mg/L） and rise velocity（0.5, 1, 2 m/h）, and each experimental ran 15 d with nine experiments.Through the analysis of CODCr, UV254 removal efficiency in each outlet, the important order of removal effect: HRT> flow rate > alkalinity.（3） In condition of HRT = 24 h, SCAR was regulated reflux ratio through the flowmeter on the return piping（R = 0, 5, 8, 13, 19）. The alkali-minimization wastewater treatment effect and the characteristics of the granular sludge were analyzed under different reflux ratio to obtain the optimal reflux ratio. The research showed that CODCr removal rate was 48.58%, UV254 removal rate was 35.24% with R = 8. In the condition of R = 8, UV254 and CODCr removal rate reached the maximum, and dehydrogenase and coenzyme F420 reached maximum concentration in each outlet. At the same time,in the condition of R = 8, the ratio of protein and polysaccharide was large and stable, and VSS increased obviously, with higher organic constituents, and microorganism quantity and activity in granular sludge.（4） The granular sludge in the first compartment of SCAR mainly consisted of spherical bacteria, bacillus and some filamentous fungi. The surface of granular sludge in the second compartment of SCAR mainly had more different shapes of holes than in the first compartment of SCAR, mainly composed of methane filamentous fungi. No.2 outlet was the most, and No.4 outlet was middle, and No.1outlet was lowest in the classification operation unit number at different height of granular sludge, consistent with the Chao 1 index, Shannon index. In the Phylum level, the advantage of bacteria was Chloroflexi and Euryarchaeota in No. 1 outlet, Chloroflexi and Proteobacteria in No. 2 and No. 4 outlet. |
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