Treatment Of CMC Wastewater By A/O-Micro Electrolysis-BAF Process

Carboxymethyl cellulose （CMC） is a kind of cellulose derivatives, easy to dissolve in water. In the industrial field, the sodium salt of sodium carboxymethyl cellulose is widely used. In the process of producing of carboxymethyl fibers will produce a certain amount of high salinity, high concentrations of wastewater, containing mainly large molecules such as cellulose, CMC, and hydroxyl, chloroacetic acid, sodium acetate, sodium chloride, ethanol and other pollutants.This kind of high salt and high concentration organic wastewater can bring serious environmental pollution and huge economic loss if it is not treated directly.This study proposes seeding halotolerant bacteria （SEM）, under no desalination and no dilution conditions, using the system treatment of A/O-micro electrolysis-BAF process to treat CMC wastewater. To prove the possibility of this high salt wastewater can be biochemical directly, and ensure the wastewater can be discharged up to the standard. With a series of experimental researches carried out, the appreciate conditions of process for CMC wastewater treatment was preliminary proved.The main results are as follows:1. By inoculation with complex salt tolerant sludge, the starting of anaerobic and aerobic reactor can be completed in 22d and 15d, respectively. The optimal operation parameters of the anaerobic reactor were that the optimal hydraulic retention time was 96h, initial pH was 7-7.5, the reaction temperature is 32-35 ℃. The optimal operation parameters of the aerobic reactor were that the optimal hydraulic retention time was 48h, initial pH was 7.0, the concentration of dissolved oxygen was 3-5mg/L,the reaction temperature is 32～35℃.2. The advanced oxidation process of micro electrolysis-Fenton can improve the biodegradability of wastewater and remove the organic pollutants further. The best reaction conditions were that:initial pH was 2.0, the reaction time was120min, H₂O₂ dosage was 4%o, under aeration conditions the COD removal rate can reached more than 45%. Orthogonal experiment also shows that the importance of influence factors of the COD removal rate, the order was:pH> reaction time> the dosage of H₂O₂.3. The results of using the upflow BAF for advanced treatment of CMC wastewater show that, the optimal hydraulic retention time was 5h, gas water ratio was 4:1, the filter height was 60cm at least,the backwash cycle was 7 days.4. The CMC wastewater after the treatment of A/O-micro electrolysis-BAF process, the effluent COD concentration was less than 100mg/L, which can meet the first grade of waste discharge standard （GB8978-1996）.The A/O-Micro electrolysis-BAF treatment process was an effective way to be applied in the practice of CMC wastewater treatment. It could provide theoretical basis and practical guidance for practical engineering design and application.