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

Abstract

In leather manufacturing, ammonium-free deliming is gaining popularity because deliming with traditionally used ammonium salts contributes ammonia-nitrogen (NH3–N) into wastewater. Wastewater contains NH3–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 NH3–N. Physicomechanical properties have been assessed in the produced effluent, delimed pelt, and crust leather. In contrast to traditional deliming, the amount of NH3–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.

Keywords

• Physicomechanical
• Ammonia-nitrogen
• Ammonium sulfate
• Organoleptic