Phosphate dosing is used by water utilities to prevent plumbosolvency in water supply networks. However, there is a lack of knowledge regarding biofilm formation on lead and plastic materials when phosphate concentrations are modified in drinking water systems. In this study, biofilms were grown over lead coupons and PVC tubes in bioreactors supplied with local drinking water treated to provide different phosphate doses (below 1, 1 and 2 mg/L) over a period of 28 days. A range of commercial iron pellets (GEH104 and WARP) were tested aiming to maintain phosphate levels below the average 1 mg/L found in drinking water. Changes in biofilm community structure in response to three different phosphate treatments were characterised by Illumina sequencing of the 16S rRNA gene for bacteria and the ITS2 gene for fungi. Scanning electron microscopy was used to visualise physical differences in biofilm development in two types of materials, lead and PVC. The experimental results from the kinetics of phosphate absorption showed that the GEH104 pellets were the best option to, in the long term, reduce phosphate levels while preventing undesirable turbidity increases in drinking water. Phosphate-enrichment promoted a reduction of bacterial diversity but increased that of fungi in biofilms. Overall, higher phosphate levels selected for microorganisms with enhanced capabilities related to phosphorus metabolism and heavy metal resistance. This research brings new insights regarding the influence of different phosphate concentrations on mixed-species biofilms formation and drinking water quality, which are relevant to inform best management practices in drinking water treatment.

自来水公司使用磷酸盐剂量来防止供水网络中的铅溶解。然而，当饮用水系统中的磷酸盐浓度发生变化时，人们对铅和塑料材料上生物膜的形成缺乏了解。在这项研究中，生物膜在生物反应器中的铅块和 PVC 管上生长，生物反应器提供经过处理的当地饮用水，在 28 天的时间内提供不同的磷酸盐剂量（低于 1、1 和 2 毫克/升）。对一系列商用铁丸（GEH104 和 WARP）进行了测试，旨在将饮用水中的磷酸盐含量保持在平均 1 毫克/升以下。通过细菌 16S rRNA 基因和真菌 ITS2 基因的 Illumina 测序来表征生物膜群落结构响应三种不同磷酸盐处理的变化。使用扫描电子显微镜观察铅和 PVC 两种材料中生物膜发育的物理差异。磷酸盐吸收动力学实验结果表明，从长远来看，GEH104 颗粒是降低磷酸盐水平同时防止饮用水浑浊度增加的最佳选择。磷酸盐富集促进了细菌多样性的减少，但增加了生物膜中真菌的多样性。总体而言，选择较高的磷酸盐水平是为了增强与磷代谢和重金属抵抗力相关的能力。这项研究带来了关于不同磷酸盐浓度对混合物种生物膜形成和饮用水质量的影响的新见解，这有助于为饮用水处理的最佳管理实践提供信息。