Pollution Loads from Leather Tanning Processing in Palestine

Abstract

The present study aims determining the pollution loads from the wastewater (WW) released from the leather tanning industry in Palestine. WW samples were collected from all leather manufacturing processes from seven tanneries located in Hebron, Palestine. The physicochem ical characteristics of the WW including, chemical oxygen demand (COD), total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), pH and chromium, were analyzed and compared. The results showed that approximately 10 m3 of WW is generated per processing of one ton of hide. The physicochemical characteristics of the released WW vary according to the manufac turing process and differ from tannery to tannery. For instance, the COD of the WW released form hair removal and liming process was the highest amongst other leather manufacturing processes, with an average value of about 8000 mg/L. The pH of the WW was greatly depen dent on the manufacturing process. The WW from pickling and tanning processes was rather acidic with pH values (2-4), whereas, liming and de-liming processes generated alkaline WW with pH values ranged between 8-12. WW resulting from washing process have the highest val ue of TS, TSS and TDS. The chromium was mainly present in the WW generated from tanning operation with an average chromium of approximately 3500 mg/L. It was mostly existed in the form of trivalent chromium (Cr+3) and only traces of the hazardous hexavalent (Cr+6) could be detected. The pollution loads discharged from leather making processes was rather high. The whole leather tanning sector releases about 29 ton of organic pollutants, 365 ton of total solids and 6 ton of chromium every year.