Design Of Internal Circulation Reactor And Research On Treatment Of Grease Wastewater

High-rate anaerobic reactors are energy saving and environmental devices in the organic treatment of wastewater. The Internal Circulation Reactor (IC reactor) the third group of high-rate anaerobic reactors, which was developed by Paques BV based on UASB reactors, can be operated at high reactor volume lading rates and high liquid up- flow velocity with low investment cost and space occupation.Because the high value COD and low SS and pH value of grease wastewater, the IC reactor was chosen as the anaerobic reactor for the research. In the experiment, the column organic glass-made IC reactor was designed with 15 mm high gas-liquid separator located at the top of the IC reactor and it is 1.35m high and 25L. The start-up and running of the full-scale IC reactor in treating grease wastewater were explored and the characteristics of granular sludge and process parameter of the running system were studied.Inoculation sludge in the start-up of the reactor is the granular sludge of the anaerobic biofilter of domestic wastewater treatment plant in Dalian and the VSS and SS of the sludge is and 59.4g/L respectively 44.7g/L.The granular sludge was black-brown and 50L was inoculated into the reactor the start-up experiment went through for 25 days. The experiment completed the start-up research of IC reactor and the results showed that the volume loading reached to 25kgCOD/(m~3·d) with the running temperature 35±1℃. Simultaneously, the removal rate of COD in the first and second reaction room was reviewed and the shape of granular sludge in the reactor was observed in the process of start-up.The methane was produced two days after start-up and the output was higher in the following days. The volume loading rose to 10kgCOD/(m~3·d) from 5kgCOD/(m~3·d) nine days after start-up with the removal rate of COD moved up to 60.4% from 42.3% .When the reactor reached to the designed running volume loading 25kgCOD/(m~3·d) the removal rate of COD was 84.3% and the HRT was 13.3h.When the reactor completely ran shabbily the runoff of the influent was adjusted and the volume loading was controlled fluctuating between 15 kgCOD/(m~3·d) and 35kgCOD/(m~3·d) with the removal rate of COD keeping between 73.4% and 85.2% and the most appropriate running loading was 25 kgCOD/(m~3·d) which was consistent with the designed running loading.The experiment loading of the influent applied to the designed reactor and when the volume loading was controlled between 15 kgCOD/(m~3·d) and 25kgCOD/(m~3·d) the VFA was basically below 300mg/L even lower than 150 mg/L sometimes which showed that the reactor ran comparatively steadily. With the running of the reactor, the sludge bed expanded continuously and the amount of little granule sludge gradually reduced. The granule sludge bigger than 1.5mm increased obviously at the bottom of the reactor so the sludge concentration also increased and the colour of the granular sludge became gray-black, black roundness and oval roundness little by little.