No abstract

To accomplish rapidly the granulation process of digestion sludge for the treatment of actual coking wastewater and meanwhile achieve high COD, phenol, SCN- and CN- removal, the EGSB reactor was employed with two operation stages. StageI: Granular sludge was formed from digestion sludge using brewery wastewater as substrate in the anaerobic way (meanwhile adding little granules, which were 1/7 of the total biomass). StageII: Granular sludge was acclimatized with the actual coking wastewater through continuous micro-oxygenation way. The experimental results showed that the granular sludge could quickly form in 10d in the EGSB reactor seeded with digestion sludge and little loose granules. It took only about 6 months for the successful micro-aerobic acclimating of the granular sludge by the actual coking wastewater. The removal efficiencies of COD, phenol, SCN- and CN- were 72.9, 99.5, 95.7 and 97.5%, respectively, at 12.1h hydraulic retention time (HRT) and for 631-922, 12.8-37.7, 66.7-232.7 and 0.3-57.8mg.L-1 influent COD, phenol, SCN- and CN- concentration.

Treatment of actual coking wastewater considered to be difficult by traditional systems. The present study is related to treatment of actual coking wastewater through microaerobic EGSB reactor. The study showed the EGSB reactor could attain about 75% high COD removal. IncreasingVupcould strength COD removal. Moreover, high sludge concentration and profound communal synergism existing within the dense granules were very important. As a result of the kinetic analysis of the EGSB reactor treating actual coking wastewater for COD removal using a modified Stover–Kincannon model, the maximum substrate utilization rate,vmax, half saturation constant,KS, inhibitor constant, KI, actual pollutant removal rate, , and the actual inhibition degree,KS/KIwere determined as 2.65×10-3h-1, 39.57mg.L-1, 415.82mg.L-1, 6.7×10-5h-1.mg-1.L and 0.1(before increasingVup), 7.34×10-3h-1, 19.53mg.L-1, 197.76mg.L-1, 3.7×10-4h-1.mg-1.L and 0.1(after increasingVup), and 9.35×10-3h-1, 6.38mg.L-1, 162.81mg.L-1, 1.47×10-3h-1.mg-1.L and 0.04 (after increasingVupand X), respectively. The inhibition of toxic contaminants in the actual coking wastewater would cause the decreasing of pollutant removal rate, however, enhancing and X (simultaneously optimizing sludge aggregate structure) could strengthen the performance effect.

Treatment of actual domestic wastewater at ambient temperature, even low temperature is considered to be difficult by traditional systems. The present study is related to treatment of actual domestic wastewater in an EGSB reactor. The study showed the effectiveness of biological treatment of actual domestic wastewater involving appropriate microorganism and granules in an EGSB reactor. At 26°C, the reactor was operated at 18.7kg COD.m−3.d−1 of average organic loading and 83% high COD removal efficiency, and even at the highest loading rate of 57.12kgCOD.m−3.d−1, the COD removal efficiency still could attain to 68%. Varied influent flow need to supply varied optimal and thus to ensure the optimal removal effect. Low temperature would cause pollutant removal rate decrease. However, enhancing could optimize the contact of sludge and wastewater and thus strengthen the performance effect. Modified Stover–Kincannon model was applied to data obtained from experimental studies in EGSB reactor. Treatment efficiencies of the reactor were investigated at different hydraulic retention times (0.5-1.3h) and different operation temperature (15°C, 26°C). The modified Stover–Kincannon model was best fitted to the EGSB reactor, and the substrate utilization rate( ), saturation constant value( ), and actual pollutant removal rate( ) were found to be , , and for 26°C, , , and for 15°C( before increasing ), and , , and for 15°C(after increasing ). Low temperature could cause decrease and thus cause distinct decreasing of COD removal efficiency. However, increasing could increase and accordingly increase COD removal efficiency.

To strengthen the COD removal from actual coking wastewater, a lab-scale granular bio-film reactor was continuously operated at three stages for about 9 months: anaerobic vs. micro-aerobic (over 2 months), with and without supplement of bicarbonate (over 2 months), and with and without supplement of diatomite (about 4 months).Compared with anaerobic condition, the micro-aerobic operation could strengthen COD removal in the actual coking wastewater and increase COD removal efficiency from 21.4% to 36.4%. At micro-aerobic operation conditions, the supplement of 3g.Linfluent-1 bicarbonate could distinctly increase COD average removal efficiency from 32.9% to 65.3%, and the supplement of 6g·L-1·d-1 diatomite could significantly increase COD average removal efficiency from 33.1% to 78.1%. The supplement of bicarbonate or diatomite for the granular bio-film reactor must be an effective way for the treatment of actual coking wastewater.