Biological treatment of oil refinery wastewater in a biosorption membrane reactor

Summary

The basic process and kinetic regularities of biomembrane and biosorption membrane treatment of fuel and lube refinery wastewater are presented. The enhancement of denitrification process is suggested by reducing the dissolved oxygen concentration in the circulating flow of activated sludge by vacuum treatment. Summarizing the results of operating a pilot vacuumizing unit the more efficient use of biosorption membrane technology compared to the biomembrane method is shown. Single dosing of 1 g of powdered activated carbon per 1 liter of mixed liquor provided for reducing the mean monthly concentration of pollutants in permeate: in COD – from 68 to 49 mg/l; in BOD_full – from 6 to 3.5 mg/l; in oil products – from 0.65 to 0.21 mg/l. The kinetic constants of the processes of eliminating the basic pollutants in membrane and biosorption membrane reactors were determined. It was stated that the specific oxidation rate in biosorption membrane reactors exceeded the similar indicators of membrane bioreactors only for easily sorbed substances – oil products and organic pollutants evaluated in BOD_full. Vacuum treatment of circulating activated sludge during 5 minutes at minus 90 kPa pressure in a membrane bioreactor provided for 2-fold reduction of the dissolved oxygen concentration, improvement of the sedimentation properties of activated sludge (compared to the flow scheme without vacuum treatment) and the dissolved oxygen concentration less than 0.5 mg/l in the anoxic zone of the membrane bioreactor.

Key words

wastewater , nitrification , activated sludge , membrane bioreactor , denitrification , oil refinery , kinetic constant , activated carbon , biosorption membrane reactor

Biosorption-membrane reactor with flat filtering elements: the calculation method

Summary

The results of studying the Don River water purification with the use of biosorption-membrane method in a biosorption-membrane reactor with flat-frame filtering elements are presented. An experimental plant with a capacity of less than 2.7 m³/day with addition of powdered activated carbon was constructed at the Novocherkassk water treatment facilities. The specific flow through the membrane was less than 17.6 l/(m²·h). The experimental results showed the high efficiency of natural water purification in a biosorption-membrane reactor that provided for meeting the requirements of Sanitary Rules and Regulations (SanPiN). The efficiency of COD reduction averaged to 41.2%, color – 57.3%, permanganate value – 33.3%. During the entire experiment no suspended solids were found in permeate. The obtained data were used as a basis for calculating the specific rate of organics oxidation estimated by COD and permanganate value. The maximum values of V_max oxidation rate and K_m Michaelis constant were determined by graphical method of double reciprocal. The permanganate value dependence of the specific organics oxidation rate and COD from temperature was obtained. Temperature constant of Van Hoff’s equation was determined by COD and permanganate value to calculate the specific rate of organic pollutants oxidation during winter (10–11 °С) and summer seasons (20–22 °С). The method of calculating a biosorption-membrane reactor is presented.

Key words

powdery activated carbon , natural water treatment , biosorption membrane reactor , specific oxidation rate , biosorption , membrane filtration

Removal of organic compounds from natural water
in a biosorption-membrane unit

Summary

The results of experimental studies on the purification of natural water of the Don River in a biosorption-membrane reactor equipped with flat-plate microfiltration membranes are presented. The research aimed at investigating the efficiency of the biosorption-membrane reactor operating with natural water with the subsequent determination of the kinetic characteristics of the running biosorption process. As a result of processing the experimental results, the efficiency of removing not only the turbidity and color of water, but also organic substances that caused high permanganate index and COD, was specified. The temperature constant was determined that provided for calculating the specific rate of oxidation of organic pollutants for the winter and summer seasons of the year. Using the obtained constants, it is possible to perform a design calculation of a biosorption-membrane reactor to any degree of purification required.

Key words

natural water , microfiltration , domestic water supply , biosorption membrane reactor , specific oxidation rate