1. Sulfur-containing wastewater: This refers to the liming wastewater and corresponding washing wastewater generated during the liming process of hair removal using the lime-alkali method. Lime-liming wastewater contains protein, lime, sodium sulfide, and suspended solids, with total CODcr at 28%, total S2- at 92%, and total SS at 75%.
2. Degreasing wastewater: This refers to the wastewater generated during the degreasing process in tanning and fur processing, where surfactants are used to treat the grease in raw hides, and the corresponding washing wastewater. The degreasing wastewater has high levels of grease, CODcr, and BOD5.
3. Chromium-containing wastewater: This refers to the waste chromium liquor and corresponding washing wastewater generated during chrome tanning and chrome retanning processes. The main pollutant in chrome tanning wastewater is the heavy metal Ce3+, with a mass concentration of approximately 3-4 q, and a weakly acidic pH.
4. Comprehensive wastewater: refers to the general term for all kinds of wastewater generated by leather and fur processing enterprises or centralized processing areas that are directly or indirectly discharged into comprehensive wastewater treatment projects (such as process wastewater and domestic sewage from the factory area).
