Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China.
Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Crops, Hainan University, Haikou 570228, China.
Water Res. 2019 Sep 1;160:70-80. doi: 10.1016/j.watres.2019.05.045. Epub 2019 May 20.
Depleted oxygen (O) in the sediment and overlying water of malodorous black water poses a potential threat to aquatic ecosystems. This study presents a method for sustainable regulation of the dissolved oxygen (DO) levels towards the malodorous black water. Oxygen-loaded natural porous materials were prepared by vacuum degassing to remove air from the pores and fill them with pure O. Capping anaerobic sediment with the prepared 6 oxygen-loaded porous materials was effective in prompting the DO concentration of the malodorous black water. Although granules activated carbon (GAC) displayed the highest oxygen-loading capability, oxygen-loaded volcanic stone additive was more efficient for long-lasting combating of the anaerobic condition because the DO level at sediment-water interface (SWI) and the DO penetration depth showed approximately 5.38- and 3.75-fold increase, respectively, compared with the untreated systems. The improvement in DO was substantially enhanced in the presence of submerged macrophyte (Vallisneria natans), during which the release of O from oxygen-loaded volcanic stone facilitated the plant growth. With the joint efforts of the O released from volcanic stone and photosynthesis by the macrophytes, the DO levels were maintained at approximately 6.80 mg/L after a 41-day incubation, which exceeded (P < 0.05) the value in only oxygen-loaded volcanic stone or macrophytes added treatments. In addition to the elevated DO level, the combined employment of oxygen-loaded volcanic stone and macrophytes triggered a negative ammonia (NH-N) flux across the SWI and an 85.82% reduction of methane (CH) production compared with those without treatment, accompanied by a decrease in total inorganic carbon and a 2.55- fold increasing of submerged macrophyte biomass, which is presumably attributed to nitrification, remineralization, and assimilation. The results obtained here shed a degree of light on the sustainable modulation of the anaerobic condition in malodorous black water.
底泥和上覆水中的耗氧（O）对水生生态系统构成了潜在威胁。本研究提出了一种可持续调节恶臭黑水溶解氧（DO）水平的方法。通过真空脱气制备了负载氧气的天然多孔材料，从孔中去除空气并用纯 O 填充。用制备的 6 种负载氧气的多孔材料覆盖厌氧沉积物，可以有效地提高恶臭黑水的 DO 浓度。虽然颗粒活性炭（GAC）显示出最高的氧气负载能力，但负载氧气的火山石添加剂在长期对抗厌氧条件方面更为有效，因为沉积物-水界面（SWI）和 DO 穿透深度分别比未处理系统增加了约 5.38 倍和 3.75 倍。在沉水植物（苦草）存在的情况下，DO 的改善得到了极大的提高，在此期间，负载氧气的火山石释放的 O 促进了植物的生长。在负载氧气的火山石释放的 O 和沉水植物光合作用的共同作用下，在 41 天的孵育后，DO 水平维持在约 6.80mg/L，超过了仅添加负载氧气的火山石或沉水植物处理的 DO 值（P<0.05）。除了提高 DO 水平外，负载氧气的火山石和沉水植物的联合使用还引发了 SWI 上负氨（NH-N）通量，并将甲烷（CH）的产生量减少了 85.82%，与未处理的相比，总无机碳减少，沉水植物生物量增加了 2.55 倍，这可能归因于硝化、再矿化和同化。本研究结果为可持续调节恶臭黑水中的厌氧条件提供了一定的思路。
