| In this paper, comprehensive dyeing printing industrial wastewater, which was made up most by alkali-minimization dyeing printing industrial wastewater from somewhere, was subjected to be investigated. From researching biological process treated with facultative-contact oxidation to remove the diagnostic pollutant terephthalic acid (TA), technical and theoretic analyzed how to reduce the enormous excess sludge. Opened out some intrinsical and diagnostic problem.Compared with traditional dyeing printing industrial wastewater, alkali-minimization dyeing printing wastewater which was characterized with TA as the principal pollutant, had much higher organic concentration, color and pH. It usually had a high COD concentration of 648-2265 mg/L, BOD 325-1346mg/L, color 250~600(dilution ratio), TA 286-1279mg/L,month average B/C 0.35 ~ 0.49.Wastewater in which pH>10 took up 75% of total wastewater around a year. The ratio of COD:N:P was 100:0.58:0.24, which indicated the nutrient of N and P for microbe of bio-treatment were far less than the necessary.Some important factors affecting wastewater biological treatment, such as temperature, MLSS (Mixed Liquor Suspended Solid), stir intensity were researched in the facultative static state. The result showed that the limit temperature should be controlled below 45℃~50℃, temperature between 35~40℃ suit the microorganism growing. Along with the increasing of concentration of MLSS, the rate of hydrolysis also increased, but too high concentration MLSS blocked the hydraulic blending. To reduce excess sludge well, at the experimental stirrer impeller diameter, the stir rate should be control at 30r/min.Some technique and parameter such as COD loading, HRT (Hydraulic Retention Time), sludge refluence, which affecting biological treatment, were optimized in the dynamic two-step facultative and contact oxidation bio-treatment system. The result showed that the COD loading should be 2.4kgCOD/m3 d, HRT of single reactor should be 10~12h. Comprehensive probed into wastewater quality parameter such as COD, color, NH3-N, SS, pH on both excess sludge refluence and no excess sludge refluence, consequently considered excess sludge refluence was feasible. The results showed that all the excess sludge can be reduced in the container, and can be got a good effluent quality. Ensured a removal efficiency of 91.3% CODCr, 97% BOD5, 62% SS, and 96% COL under experiment condition. And sludge cycled back to AI can be benefit to get rid of the color from wastewater and recruit nutrition and phosphor to the system, result showed that sludge cycled back can reduce 37.5% COL compared with no sludge refluence.The concentration of MLSS in every container arise when the excess sludge full back to AI, the MLSS concentration of 0 (Oxidation) container arise about 30%, but the excess sludge reducing is successfully from integer. The quantity of excess sludge discharge reduced 4.48g/d compared with no excess sludge recycling. Within experimental time, under the condition of experiment, the excess sludge reducing rate is 100%, so use this process can get the result of no excess sludge discharge.TA could be removed quickly from wastewater in aerobic condition, the removal rate of TA can be above 96% within 12~16h of HRT. By contrast, facultative system could only degraded 15.3% within 210h of HRT. TA made up 40-78% of the total COD of alkali-minimization dyeing printing wastewater, the mean is 55%. The biodegradation characteristic of TA illustrated that aerobic biological system should be in charge of this kind of wastewater treatment.The modeling of excess sludge reducing by hydrolysis and the modeling of TA biodegraded kinetic were set up; the experimental data verification for model equation is satisfactory. According to the model analysis, easily biodegradable substrates co-existence is a inhibitors for TA biodegradation. Within the limit of range, a two-step facultative and contact oxidation bio-treatment system, dealing with this kind of wastewater is suggested.
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