牛皮铬鞣废液循环过程中关键成分及水质特征分析

Components and characteristics of reused chrome liquor in recycling tanning system

针对铬鞣废液循环工艺技术在某制革企业工业化应用的实际效果进行了跟踪研究,研究中对连续循环30次铬鞣废液中总铬、Cl-和SO42-含量的变化,水质污染特征和蓝湿革收缩温度的动态变化进行了监测。结果表明:总铬含量在前15次循环有上升趋势,后期基本稳定;Cl-含量在循环15次前有所下降,后期稳定在17~18 g/L;SO42-含量基本处于稳定状态,约600 mg/L。铬鞣废液在循环30次后水质污染特征分析结果显示:循环前期CODCr含量逐渐上升,在循环15次后趋于平衡;NH4+-N在循环15次后稳定于400 mg/L左右,30次后约200 mg/L;铬鞣废液TOC含量稳定在1 000~1 400 mg/L,基本上呈现先上升后期稳定的趋势。铬鞣废液分别在循环第15次、第10次以后未检出六价铬的存在,且循环后鞣制的蓝湿革收缩温度均在95℃以上,耐湿热稳定性良好,基本满足后期应用条件,实践证明本试验所用铬鞣废液循环利用工艺技术是安全环保可行的,且风险较低,对后期的推广具有重要意义。

The key components and effluent characteristics of chrome tanning system were analyzed, which tookfrom commercial process effluent of a tannery based on the closed-loop chrome tanning system. The total chromiumcontent, Cl-and SO42- content, the effluent characteristics of chrome tanning solution and shrinkage temperature ofwet blue leather in 30 cycles of chrome tanning solution were analyzed. The experimental results show that the total chromium content increases in the first 15 cycles and is stable in the later period, Clcontent decreases before 15 cy-cles and stabilized between 17 g/L and 18 g/L in the later period, SO42- content was basically stable, about 600 mg/L. The analysis results of water pollution characteristics of chromium waste liquor after 30 cycles show that the CODCrcontent increases gradually in the early stage of the cycle and tended to balance after 15 cycles. NH4+-N stabilizes atabout 400 mg/L after 15 cycles and about 200 mg/L after 30 cycles. The TOC of chromium liquor remained stable be-tween 1 000 mg/L and 1 400 mg/L. Basically, it shows the phenomenon of rising first and stabilizing later. No hexa-valent chromium is detected in chrome tanning liquor after the fifteenth and tenth cycles, and the shrinkage tempera-ture of wet blue leather sheet after cycles is above 95 ℃. The wet-heat stability is good, which basically meets the lat-er application conditions. The practice proves that the recycling technology of waste chrome tanning liquor provided byBIOSK is safe and environmentally feasible. And the risk is low, which is of great significance to the later promotion.