Liu Dongpo, Jin Juntao, Liang Sichen, Zhang Jinsong
Shenzhen Water (Group) Co., Ltd Shenzhen 518035 Guangdong China.
School of Civil Engineering Guangzhou 510006 Guangdong China.
RSC Adv. 2019 Jan 30;9(7):4035-4047. doi: 10.1039/c8ra08645a. eCollection 2019 Jan 25.
Many cities in China have implemented urban water supply pipe network renovation projects; however, at the beginning of new pipeline replacements, customers often complain about water quality problems, such as red water, odour and other water quality problems. To overcome these frequent water quality problems, this study selected a commonly used ductile cast iron (DCI) pipe, stainless steel (SS) pipe and high-density polyethylene (HDPE) pipe for laboratory simulations of the water quality regularity of new pipes, the variations in pipe inner walls, and the presence of microbial communities. Based on the research results, combined with actual water sample analysis, the stabilisation time of the interaction between the tubings inner walls and bulk water was determined, to allow pipeline cleaning and water quality maintenance. The results showed that the water quality change in the DCI was the most significant, while the SS and the HDPE pipes showed consistent changes with severe initial deterioration, then later stabilisation to meet the required standard. The DCI inner wall changed from a loose porous particle shape to a relatively dense and irregular three-dimensional shape, with the constituent elements mainly being O and Ca. The SS inner wall had a uniform structure in the early stage, but are obvious spherical balls of different sizes formed later, with the elemental composition here mainly being C and O. The HDPE inner wall was smooth and had small perforations in the early stage, while the perforation in the middle and late stages increased to become rough and scale-like at a much later stage. The proportion of Proteobacteria in effluents (72.82% to 86.87%) was significantly increased compared with the influent (48.45%), while the proportion of Proteobacteria (86.87%) in the DCI was significantly higher than in the SS (74.28%) and HDPE pipes (81.68%). Moreover, compared with the influent (23.33%), the Bacteroidetes (2.79% to 3.32%) levels in the effluents were significantly reduced, indicating that the pipe material affects the microbial abundance in water.
中国许多城市都实施了城市供水管网改造工程；然而，在新管道更换初期，用户经常抱怨水质问题，如黄水、异味等水质问题。为克服这些常见的水质问题，本研究选取了常用的球墨铸铁（DCI）管、不锈钢（SS）管和高密度聚乙烯（HDPE）管，对新管道的水质规律、管道内壁变化以及微生物群落的存在情况进行实验室模拟。根据研究结果，结合实际水样分析，确定了管材内壁与主体水相互作用的稳定时间，以便进行管道清洗和水质维护。结果表明，DCI管的水质变化最为显著，而SS管和HDPE管的变化趋势一致，初期水质严重恶化，随后趋于稳定并达到要求标准。DCI管内壁从疏松多孔颗粒状变为相对致密且不规则的三维形状，其组成元素主要为O和Ca。SS管内壁初期结构均匀，但后期形成明显大小不同的球形颗粒，此处元素组成主要为C和O。HDPE管内壁初期光滑，有小穿孔，中后期穿孔增多，后期变得粗糙且呈鳞片状。与进水（48.45%）相比，出水（72.82%至86.87%）中变形菌门的比例显著增加，而DCI管中变形菌门（86.87%）的比例显著高于SS管（74.28%）和HDPE管（81.68%）。此外，与进水（23.33%）相比，出水（2.79%至3.32%）中拟杆菌门的水平显著降低，表明管材会影响水中微生物的丰度。
