Effluent polishing with the use of ultrafiltration

Summary

The results of investigating the removal of phosphate ions and suspended solids that enhance eutrophication of water bodies from biologically treated domestic wastewater after secondary settling tank are presented. Experimental studies of effluent polishing with the use of ultrafiltration technology in combination with coagulation were carried in the laboratory of the Nizhny Novgorod State University of Architecture and Civil Engineering. The aluminium hydroxychloride dosage of 20 mg/l as Al2O3 was used as a coagulant. Hollow-fiber module manufactured by Fazerkraft Russian Company with polyvinylidenefluoride was used for tangential ultrafiltration in cycle mode. The membrane module is a device with a cylindrical shell with a bunch of hollow fibers inside with porous walls. The impact of transmembrane pressure on the filtration process was investigated. It was found that the specific flow rate of permeate increases with the increase of transmembrane pressure within the range of 0.05–0.2 bar. The tests showed that 20-fold increasing the concentration of the suspension subject to treatment does not result in any significant decrease of permeate production of the membrane module. Increasing recycling rate (of tangential flow) results in the increase of permeate flow; however, on account of technical and economic aspects, the range of low recycle flow values is of most interest. The results of the studies showed that the suggested ultrafiltration technology provided for almost complete elimination of suspended solids (more than 93% treatment efficiency), 97% reduction of phosphates in wastewater, and reduction to 0.04 mg/l aluminium concentration in permeate.

Key words

suspended substances , membrane module , wastewater aftertreatment , phosphates , ultrafiltration

Wastewater Aftertreatment on Granular Bed Filters

Summary

Problems of the wastewater aftertreatment on granular filters of different design are described. Advantages of Ecopolymer drainage systems at reconstruction of these filters are shown. On the basis of generalization of its firsthand knowledge the Ecopolymer Group of Companies in the course of designing of wastewater aftertreatment uses rapid filters with descending filtration, air-water washing and rinse water low discharge system consisting of Ecopolymer sand-catching chutes and stream-guiding protuberances. Filters are equipped with the Ecopolymer drainage-distribution system consisting of drainage filters and Ecopolymer aerators. Conditions required for successful operation of wastewater aftertreatment rapid filters are defined. Results of operation of such filters designed by the Ecopolymer Company are presented.

Key words

granular media , rapid filter , drainage-distribution system , wastewater aftertreatment , filtration cycle

Removing heavy metal ions from wastewater in the process
of tertiary treatment with a new sorbent based on modified clays

Summary

The concentrations of heavy metal ions present in municipal and industrial wastewater after biological treatment often exceed the maximum permissible values set for fishery water bodies. Sorption on activated carbon is a popular method in wastewater tertiary treatment practice. However, activated carbon is rather expensive and ineffective in removing heavy metal ions. Lately zeolites that provide for meeting MPC_fishery waterbodies in tertiary treatment have been used; however, their sorption capacity is low. In ordert to reduce the cost of tertiary treatment brand new sorption materials that are free from shortcomings of activated carbon and zeolites, widely used and affordable are required. The results of studying the removal of heavy metal ions from the model multicomponent solution with the use of new sorbents based on modified clays and peat from the Samara Region are presented. The activation was executed by thermal method. For the enhanced removal of copper, iron, manganese, zinc and lead ions from effluents the sorbent prepared from two clay types and peat in equal ratio with polyvinil acetate emulsion as a bonding agent turned to be most efficient. The required contact time of sorbent and solution was 90 minutes. For aluminium removal a sorbent prepared from two clay types, peat,wood ash and polyvinil acetate can be used with 150 minutes contact time with the solution. Sorbents prepared on the basis oft he Samara Region clays provide for meeting MPC_fishery waterbodies in the process of removing copper, iron, manganese, zinc, lead and aluminium from municipal and industrial effluents after biological treatment.

Key words

wastewater aftertreatment , sorbent , heavy metal ions , modified clay , sorption kinetics