Economical Treatment Method for Waste Pickling Liquor for Micro, Small and Medium Scale Enterprises

Abstract

Waste pickling liquor is pertinent to hazardous waste. Various types of recovery and regeneration methods are used to recover and regenerate the acid and metals from waste pickling liquor. But these methods are sumptuous and not amenable for small scale industries. In a developing country like India, where lots of micro, small and medium scale industries exist, only precipitation is a pecuniary treatment method but it generates lots of sludge. There are severe problems in its disposal to lined sites (landfills). This study has been undertaken to minimize the generation of the pickling sludge by different neutralizing agents and their combinations with economic valuation and also sludge characterization has been done. The results show that the treatment of pickling effluent with lime only is the economical solution but the quantity of sludge generation is on a higher side. However, the authors recommend 20% calcium hydroxide and 80% sodium hydroxide for the treatment because sludge reduction is appreciable and lower sludge generation will result in lower cost of sludge handling, i.e., sludge collection, transportation and disposal arrangement. The sludge characterization results show that the sludge generated by treatment of WPL requires further treatment before using it as a building material.