Solid organic acid, aminopolycarboxylic acid and alkali salt in deliming to reduce nitrogenous pollution in tannery wastewater.

In leather manufacturing, ammonium-free deliming is gaining popularity because deliming with traditionally used ammonium salts contributes ammonia-nitrogen (NH-N) into wastewater. Wastewater contains NH-N effect on the treatment facility. In this study, an ammonia-free deliming agent-a combination of citric acid (CA), sodium hexametaphosphate (SHMP), and ethylenediaminetetraacetic acid (EDTA) is utilized against the traditional deliming agent to limit the release of NH-N. Physicomechanical properties have been assessed in the produced effluent, delimed pelt, and crust leather. In contrast to traditional deliming, the amount of NH-N and Total Kjeldahl Nitrogen (TKN) is estimated to have decreased by 98.1 % and 85.26 %, respectively. Deliming with CA + SHMP + EDTA can significantly reduce the amount of TKN in the deliming float. A notable reduction of biochemical oxygen demand (34.8 %), chemical oxygen demand (85.7 %), total dissolved solids (56.4 %), electrical conductivity (54.5 %), and turbidity (65.2 %) was achieved. The physical and organoleptic characteristics of crust leathers produced with the CA + SHMP + EDTA deliming process are comparable to the traditional deliming technique. Similar fiber structure is observed in SEM images of crust leather, wet blue leather, limed pelt, and delimed pelt. A pilot-scale production is carried out; the outcomes are similar to the experimental results. For all experimental and control investigations, the Pseudo Second Order kinetic model fits the reaction kinetics. Deliming with CA + SHMP + EDTA offers a simpler wastewater treatment process since it reduces nitrogen contamination in the wastewater.