School of Environment, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou, 510006, China.
School of Environmental Science & Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
Water Res. 2021 May 1;195:116999. doi: 10.1016/j.watres.2021.116999. Epub 2021 Mar 3.
Elemental sulfur (S) reduction process has been demonstrated as an attractive and cost-efficient approach for metal-laden wastewater treatment in lab-scale studies. However, the system performance and stability have not been evaluated in pilot- or large-scale wastewater treatment. Especially, the sulfide production rate and microbial community structure may significantly vary from lab-scale system to pilot- or large-scale systems using real domestic sewage as carbon source, which brings questions to this novel technology. In this study, therefore, a pilot-scale sulfur-based sulfidogenic treatment system was newly developed and applied for the treatment of Cu-laden electroplating wastewaters using domestic sewage as carbon source. During the 175-d operation, >99.9% of Cu (i.e., 5580 and 1187 mg Cu/L for two types of electroplating wastewaters) was efficiently removed by the biogenic hydrogen sulfide that produced through S reduction. Relatively high level of sulfide production (200 mg S/L) can be achieved by utilizing organics in raw domestic sewage, which was easily affected by the organic content and pH value of the domestic sewage. The long-term feeding of domestic sewage significantly re-shaped the microbial community in sulfur-reducing bioreactors. Compared to the reported lab-scale bioreactors, higher microbial community diversity was found in our pilot-scale bioreactors. The presence of hydrolytic, fermentative and sulfur-reducing bacteria was the critical factor for system stability. Accordingly, a two-step ecological interaction among fermentative and sulfur-reducing bacteria was newly proposed for sulfide production: biodegradable particulate organic carbon (BPOC) was firstly degraded to dissolved organic carbon (DOC) by the hydrolytic and fermentative bacteria. Then, sulfur-reducing bacteria utilized the total DOC (both DOC degraded from BPOC and the original DOC present in domestic sewage) as electron donor and reduced the S to sulfide. Afterwards, the sulfide precipitated Cu in the post sedimentation tank. Compared with other reported technologies, the sulfur-based treatment system remarkable reduced the total chemical cost by 87.5‒99.6% for the same level of Cu removal. Therefore, this pilot-scale study demonstrated that S reduction process can be a sustainable technology to generate sulfide for the co-treatment of Cu-laden electroplating wastewater and domestic sewage, achieving higher Curemoval and higher cost-effectiveness than the conventional technologies.
元素硫（S）还原过程已被证明是一种有吸引力且具有成本效益的方法，可用于实验室规模的含金属废水处理。然而，该系统的性能和稳定性尚未在中试或大规模废水处理中进行评估。特别是，使用实际生活污水作为碳源时，硫化物产生速率和微生物群落结构可能会显著不同于实验室规模系统，这给这项新技术带来了疑问。因此，在这项研究中，我们新开发了一个中试规模的基于硫的硫化物生成处理系统，并将其应用于使用生活污水作为碳源处理含铜电镀废水。在 175 天的运行过程中，通过 S 还原产生的生物氢硫化物有效地去除了两种类型电镀废水中超过 99.9%的铜（即 5580 和 1187 mg Cu/L）。通过利用原生活污水中的有机物，可以达到相对较高的硫化物产生水平（200 mg S/L），但这很容易受到生活污水中有机物含量和 pH 值的影响。长期使用生活污水会显著改变硫还原生物反应器中的微生物群落。与报道的实验室规模生物反应器相比，我们的中试规模生物反应器中发现了更高的微生物群落多样性。水解、发酵和硫还原细菌的存在是系统稳定的关键因素。因此，我们提出了一种新的发酵和硫还原细菌之间两步生态相互作用的理论，用于硫化物的产生：首先，水解和发酵细菌将可生物降解的颗粒有机碳（BPOC）降解为溶解有机碳（DOC）。然后，硫还原细菌利用总 DOC（DOC 从 BPOC 降解和生活污水中原有的 DOC）作为电子供体并将 S 还原为硫化物。随后，硫化物将在后沉淀池中的 Cu 沉淀下来。与其他报道的技术相比，基于硫的处理系统可将总化学成本显著降低 87.5%至 99.6%，同时实现相同水平的 Cu 去除。因此，这项中试研究表明，S 还原过程可以成为一种可持续的技术，用于生成硫化物以共处理含铜电镀废水和生活污水，与传统技术相比，可实现更高的 Curemoval 和更高的成本效益。
