Study On Biodegradation And Engineering Of Natural Pigment Production Wastewater By Anaerobic Combined Aerobic Process

A large amount of waste water will be produced in the process of extracting natural pigments from plants.This kind of wastewater has high chemical oxygen demand(COD),low p H value,and large chroma.In this study,shake flask experiments were used to verify the biochemical feasibility of anaerobic treatment of natural pigment production wastewater.After that,a lab-scale continuous flow reactor was used to treat natural pigment production wastewater.The microbial community structure and changes before and after reactor operation were analyzed.Finally,applied this technology in pilot and full-scale plant.Provides reliable data support for engineering applications of anaerobic/aerobic treatment of natural pigment production wastewater.In this study,the SBR experiment was used to prove that: after removing the suspended solids in the influent,the reaction temperature was 35 °C,the p H value was 8.5,and the influent COD was 4000 mg/L,the lowest effluent COD of the shake flask was 919 mg/L.Both first-order and second-order kinetic models can fit the reaction well.The lab-scale continuous flow reactor is a laboratory-made reactor.The anaerobic reactor has a working volume of 3.5 L and the aerobic reactor has a working volume of 4.32 L.The anaerobic reactor operates at 33 °C and the aerobic reactor operated at room temperature.The start-up volume load of the anaerobic reactor was 1kg COD/(m3·d).The experiment increased the water influent load by reducing the hydraulic residence time.When the hydraulic retention time(HRT)of the reactor was reduced to 22 h,the maximum volume load was 6 kg COD/(m3d),the effluent COD was increased to more than 2000 mg/L,and the effluent alkalinity is reduced to 7mmol/L.The aerobic reactor in a small laboratory test performed was general.The highest volume load was only 0.1 kg COD/(m3·d).The study used high-throughput sequencing technology to analyze the changes of microbial community structure before and after the operation of the laboratory reactor.Mi Seq sequencing results showed that the total amount of sludge was increasedduring the operation of the reactor,but the diversity decreased and the community structure changed.Bacteria at the highest level of abundance in anaerobic reactors at the phylum level is the same as reported for degradation of natural pigment production wastewater.Proteobacteria,Bacteroidetes and Planctomycetes are the dominant bacteria in aerobic sludge.Bacteria have a significant increase in the abundance of bacteria with hydrolytic acidification,degradation of refractory contaminants,and denitrification at the genus level.The pilot test was conducted at the factory site with a volume of 231 L and a maximum volume load of 4 kg COD/(m3·d).After the renovation of the water treatment facilities in the plant has been completed,we also recorded the on-site project commissioning results.The commissioning data showed that when the anaerobic reactor enters a stable period,the influent load is 5 kg COD/(m3·d)and the effluent COD is 500 mg/L.Only anaerobic removal efficiency can reach over 90%.During the adjustment process,the maximum load of the aerobic reactor can reach0.7 kg COD/(m3d),and the effluent COD can still reach 400 mg/L.