Solid dicarboxylic acid assisted deliming in beamhouse to reduce nitrogen compounds in tannery wastewater

Abstract

In leather manufacturing, ammonia salts in deliming operations contribute to the significant addition of ammonia-nitrogen (NH3–N) into wastewater. Wastewater containing NH3–N serious affects aquatic life and the operations of effluent treatment plants. In this study, the strategy of reducing NH3–N released into tannery wastewater, uses non-ammonia deliming agent-solid dicarboxylic acid (malonic acid) to replace the conventional deliming agent (ammonium sulfate). Utilizing a laboratory experiment, a pilot scale test was carried out and found to be almost comparable with the former experimental work. The generated delimed wastewater, delimed pelts, and manufactured crust leathers were subjected to various physicomechanical analyses. Results revealed that the reductions of NH3–N, TKN, and hydroxyproline amounted, respectively, to 98.78%, 88.69%, and 26.9%, compared to conventional deliming agents. The other pollutants, namely TDS, BOD, COD, and EC were significantly reduced. The physicomechanical properties of the crust leathers met the standard requirements. SEM images of delimed pelt and crust leathers revealed a similar fiber structure. The wastewater emitted during deliming with malonic acid is probably an easier way to conduct effluent treatment by reducing nitrogen pollution. This investigation is a novel approach to finding a viable technology that can satisfy the need for modern leather manufacturing being done in environmentally friendly ways.