Pilot-scale Study On Dye Wastewater Treatment By Compound Anaerobic Baffled Reactor

Dye wastewater is characterized by complex quality, high pH, low biodegradability and so on, which is difficult to be discharged under standard by single aerobic biological treatment. Therefore, this study used a pilot-scale compound anaerobic baffled reactor (ABR) to treat dye wastewater, which utilized the hydrolyzation and acidification of the anaerobic microbes to degrade the complex organic matter in dye wastewater to simple one which could be easily used by aerobic microbes. This study identified technical parameters for steady operation of the modified anaerobic baffled reactor, and thus supplied basis and reference for decision making for the design and operation of the anaerobic part revamp engineering of the First Period Engineering in Shaoxing Water Treatment and Development Ltd.This study investigated the startup and operation performance of the modified anaerobic baffled reactor. The pilot-scale trial results showed that the reactor were successfully started up under the condition that influent COD range was 700~1 300 mg/L, HRT was 60 h, pH 7.0~8.5, hydraulic load range 9.3 m~3/(m~2·d) and volume load 0.4 kgCOD/(m~3·d). The modified anaerobic baffled reactor reduced the organic matter type number from 84 to 44, effectively removed some types of dye; when pH fluctuated between 7.0 and 9.0, the effect of hydrolyzation and acidification was evident, the average COD removal efficiency was 28.6 % and the ratio of BOD to COD from 0.27 to 0.35; when pH fluctuated between 6.5 and 7.2, the effect of methanogenesis was intensified, and the average COD removal efficiency reached 40.0 %. The average SS removal efficiency was 40.8 %.After the effluent of the compound ABR was treated by aerobic process, the COD variation range was 104~142 mg/L, the average of which was 124 mg/L. The effluent could be discharged under standard after cogulation treatment by a small amount of aluminium sulfate. The compound ABR reduced the pollution degree of dye wastewater, improved its biodegradability, decreased its pH variation range, and thus supplied favorable conditions for the steady operation of the latter aerobic part.The results of generalized grey relational analysis showed that hydraulic load, volume load, water temperature and influent SS greatly influenced COD removal efficiency. Based on the operational performance of the modified anaerobic baffled reactor and the results of generalized grey relational analysis maintained in a certain range: technical parameters for steady operation of the reactor were identified: HRT 12 h; pH range 7.0~9.0; alkalinity range 600~1400 mg/L; ORP range -450~-550 mV; hydraulic load range range 40~48 m~3/(m~2·d), volume load range 1.3~2.5 kgCOD/(m~3·d).Based on comprehensive analysis on the influencing factors of COD removal efficiency of the reactor, it is suggested that the maximum elevation of hydraulic load of the reactor should not be higher than 3 m~3/(m~2·d) per day; there is no need to regulate the reactor temperature, but it is better to take some insulation measures; it is necessary to discharge a proper amount of sludge at the bottom of each compartment in time.