Department of Chemical Engineering, Complutense University of Madrid, Facultad de Ciencias Químicas, Ciudad Universitaria s/n, 28040 Madrid, Spain.
Waste Manag. 2012 Jun;32(6):1236-43. doi: 10.1016/j.wasman.2011.12.011. Epub 2012 Jan 13.
According to current environmental legislation concerned with water scarcity, paper industry is being forced to adopt a zero liquid effluent policy. In consequence, reverse osmosis (RO) systems are being assessed as the final step of effluent treatment trains aiming to recover final wastewater and reuse it as process water. One of the most important drawbacks of these treatments is the production of a retentated stream, which is usually highly loaded with biorecalcitrant organic matter and inorganics; and this effluent must meet current legislation stringent constraints before being ultimately disposed. The treatment of biorefractory RO retentate from a paper mill by several promising advanced oxidation processes (AOPs) - conventional Fenton, photo-Fenton and photocatalysis - was optimized considering the effect and interaction of reaction parameters; particularly using response surface methodology (RSM) when appropriate (Fenton processes). The economical cost of these treatments was also comparatively assessed. Photo-Fenton process was able to totally remove the COD of the retentate, and resulted even operatively cheaper at high COD removal levels than conventional Fenton, which achieved an 80% reduction of the COD at best. In addition, although these optimal results were produced at pH=2.8, it was also tested that Fenton processes are able to achieve good COD reduction efficiencies (>60%) without adjusting the initial pH value, provided the natural pH of this wastewater was close to neutral. Finally, although TiO(2)-photocatalysis showed the least efficient and most expensive figures, it improved the biodegradability of the retentate, so its combination with a final biological step almost achieved the total removal of the COD.
根据当前有关水资源短缺的环境法规，造纸业被迫采取零液体排放政策。因此，反渗透 (RO) 系统被评估为废水处理工艺的最后一步，旨在回收最终废水并将其再用作工艺用水。这些处理方法的一个最重要的缺点是产生了浓缩物流，其中通常含有大量生物难降解的有机物和无机物；并且在最终处置之前，必须满足当前法规对这种废水的严格限制。通过几种有前途的高级氧化工艺 (AOP)——传统芬顿法、光芬顿法和光催化法——对造纸厂的 RO 浓缩物进行了处理，优化了反应参数的影响和相互作用；特别是在适当的情况下（芬顿工艺）使用响应面法 (RSM)。还比较评估了这些处理方法的经济成本。光芬顿法能够完全去除浓缩物的 COD，并且在高 COD 去除水平下的操作成本甚至比传统芬顿法更便宜，传统芬顿法的 COD 去除率最高可达 80%。此外，尽管这些最佳结果是在 pH=2.8 下产生的，但还测试了芬顿工艺能够在不调节初始 pH 值的情况下实现良好的 COD 去除效率（>60%），只要这种废水的自然 pH 值接近中性即可。最后，尽管 TiO(2)-光催化法的效率最低且成本最高，但它提高了浓缩物的生物降解性，因此与最终的生物步骤结合几乎可以实现 COD 的完全去除。
