Research And Optimization On Treatment Process Of Molasses Alcohol Wastewater

Molasses wastewater as an organic wastewater from the anaerobic effluent, being higher chemical oxygen demand (COD) and dark brown chroma is extremely difficult to be disposed. In this study, COD and chroma removal of the wastewater were investigated involved on the five processes, including the combination of hydrolysis acidification and aerobic treatment, the adsorption of activated carbon, diatomite filtration, electrocoagulation treatment and the combination of aerobic treatment and electrocoagulation. And, the process conditions were optimized and cost was taken into account. Furthermore, the effect of electrocoagulation technology on other characterization of wastewater was investigated.By comparing the COD and chroma removal in five treatment processes, it is shown that COD and chroma removal efficiencies were up to 17.78% and 1.8% respectively when the combination of hydrolysis acidification and aerobic treatment was used and those of activated carbon adsorption and diatomite filtration were respectively 17.9% and 39.3%, 1.56% and 2.7%. Those of electrocoagulation technology were 48.02% and 63.66%, but it produced large amounts of foam which blocked the reactor. The problem was solved by diluting ten-fold for raw wastewater, COD and chroma removal efficiencies were respectively improved to 65.1% and 74.2%. In addition, the effect of secondary and tertiary electrocoagulation technology on COD and chroma removal efficiencies were carried out, and it csn rise up to 77.4% and 95.8%, 85.1% and 98.5% using an aluminum anode respectively.According to the characterization of actual raw wastewater, the combination of aerobic treatment and electrocoagulation technology was used. The results showed that COD decreased to 821 mg/L from 1410 mg/L and chroma was down to 650 times from 700 times in the aerobic treatment periods. In electrocoagulation treatment periods, the smaller the electrode distance was, the better the removal efficiency was, but too much would lead to the non-uniform stirring. So the optimal condition was electrode distance of 3 cm. And suitable pH of the wastewater was itself 7.83. Higher current density and longer electrolysis time benifited COD and chroma removal. The removal efficiency with an iron anode was superior to that of an aluminum anode for primary electrocoagulation, and COD and chroma of effluent can respectively reach 172 mg/L and 20 times. Furthermore, the more the electrocoagulation order was, the better the removal efficiency was. Taken into account economic view, electrocoagulation cost with iron anode was higher than that of aluminum anode. In addition, the concentration of NH3-N and the conductivity of the solution reduced, but pH was up to 10.82 from 7.83 in 30 minutes using aluminum anode for primary electrocoagulation.