Comprehensive process solutions for oily wastewater treatment

Summary

The demand for a comprehensive solution of the problems of construction and upgrade of the local wastewater treatment facilities necessitates the need in manufacturing equipment sets that provide for the complete oily wastewater treatment cycle. Based on the experience in this field a most efficient economically feasible technology of industrial wastewater treatment – dissolved-air chemical flotation with subsequent filtration in different filter types is proposed. «Ecoservice» Company has developed modular treatment facilities placed in container units or demountable buildings. These are ECO-LS units (for storm water treatment), ECO-AM (for car wash sites) etc. For the enterprises of «Russian Railways» ECO-NS unit was developed that had a compliance certificate and an expert report of Rospotrebnadzor. In this unit the comprehensive approach to the treatment technology – chemical dissolved air flotation, mechanical filtration and sorption was implemented. The versatility of this scheme is in the use of different flotation units depending on the wastewater pollution level. Besides, the use of different filter media provides for eliminating specific pollutants – ammonium, phenols, heavy metals. The complex unit is designed for wastewater treatment to the standard of effluent discharge into fishery water bodies. Despite the fact that the given complex unit has been developed for «Russian Railways» enterprises it can be used in other industries to remove oil products from wastewater.

Key words

filtration , sorption , local treatment facilities , oil effluents , comprehensive technology , chemical flotation , modular treatment facilities

Oilfield wastewater treatment with the use of centrifugal apparatuses

Summary

The task of the studies was improving the efficiency of polydisperse oil particles removal from oilfield wastewater. The process is complicated with the presence of adsorption (inhibiting) shells of mechanical impurities on fine-dispersed oil droplets. A new technology of oilfield wastewater treatment is suggested that provides for wastewater pretreatment in hydraulic cyclones equipped with cylindrical (tubular) overflow chambers that allow stimulating the processes of oil droplets coalescence. The flow sheet of a pilot plant for studying the processes of emulsified oil droplets growth is presented. The plant comprises a hydraulic cyclone connected to the upper and lower overflow chambers. Oilfield wastewater of «Tatneft» OJSC was chosen as a test subject (oil concentration 710–800 mg/l). It was stated that the coalescence efficiency was determined by the vortex value parameter in overflow chambers and by the time of wastewater treatment in the centrifugal field. Processing the test results on the oil droplet size distribution showed that the optimal vortex parameter values for the upper overflow chamber of the hydraulic cyclone were within 20–23; whereas for the lower overflow chamber – 16–18.5. The recommended time of wastewater treatment in the upper and lower overflow chambers was relatively 24.5 and 18.5 seconds. It was experimentally determined that the residual oil concentration after oilfield wastewater treatment in the hydraulic cyclone and two hours sedimentation was less than 72 mg/l at 91% treatment efficiency. It was 6% higher compared with the wastewater sedimentation efficiency after treatment in the hydraulic cyclone only. The design of BGTO plant (hydraulic cyclone block – overflow chamber – sedimentation tank) is suggested that provides for the efficient treatment of oil effluents on industrial scale.

Key words

settling , hydrocyclone , oil effluents , oil droplet coalescence , overflow chamber , treatment plant