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

Results of studying the removal of heavy metal ions from industrial wastewater

Summary

The results of studies on the removal of heavy metal ions from acid-base wastewater of electroplating industry by neutralization, sedimentation and filtration are presented. During a laboratory experiment carried out with processing real acid-base wastewater of one of the enterprises in Samara with caustic soda, the optimal pH range found was 9.8–10.6. Using a flow through model of a vertical settling tank, the calculated hydraulic size of the suspension generated during the alkalization of the given wastewater category was determined that can be taken as 0.28 mm/s. The level of heavy metal ion removal in the process of galvanic wastewater treatment according to the flow scheme «pH adjustment – settling tank – filter with granular media» was experimentally determined in mg/l as: total iron 0.42–0.97; copper 0.028–0.087; nickel 0.016–0.073; zinc 0.047–0.28; cadmium 0.006–0.016. At the same time, the requirements for receiving industrial effluents into the Samara municipal sewer were met only for iron; whereas, the concentrations of other metals ranged from 0.85 to 13.3 shares of the permissible concentrations; therefore, in order to achieve the established standards, additional treatment was required, for example, by sorption.

Key words

wastewater , hydraulic size , filtration , galvanic production , heavy metal ions , neutralization