Commonwealth Scientific and Industrial Research Organisation (CSIRO), Environment, Waite Campus, South Australia, Australia.
CSIRO, Environment, Lucas Heights, NSW 2234, Australia.
Sci Total Environ. 2024 Nov 25;953:175924. doi: 10.1016/j.scitotenv.2024.175924. Epub 2024 Sep 2.
Sewer overflows are an environmental concern due to their potential to introduce contaminants that can adversely affect downstream aquatic ecosystems. As these overflows can occur during rainfall events, the influence of rainwater ingress from inflow and infiltration on raw untreated wastewater (influent) within the sewer is a critical factor influencing the dilution and toxicity of the contaminants. The Vineyard sewer carrier in the greater city of Sydney, Australia, was selected for an ecotoxicological investigation of a sanitary (separate from stormwater) sewerage system and a wet-weather overflow (WWO). Three influent samples were collected representing dry-weather (DW), intermediate wet-weather (IWW) and wet-weather (WW). In addition, a receiving water sample was also collected downstream in Vineyard Creek (WW-DS) coinciding with a WWO. We employed direct toxicity assessment (DTA) and toxicity identification evaluation (TIE) approaches to gain comprehensive insights into the nature and magnitude of the impact on influent from rainwater ingress into the sewer. Three standard ecotoxicological model species, a microalga, Chlorella vulgaris, the water flea, Ceriodaphnia dubia and the midge larva, Chironomus tepperi were used for both acute and chronic tests. The study revealed variable toxicity responses, with the sample of influent collected in wet-weather displaying lower toxicity compared to the dry-weather sample of influent. Ammonia, and metals, were identified in dry weather as contributors to the observed toxicity, however, this risk was alleviated through rainwater ingress in wet-weather with further dilution within the receiving water. Based on toxicity data, dilutions of influent to minimise effects on C. vulgaris and C. dubia ranged from 1 in 12 in DW to 1 in 2.8 in WW, and further diminished in the receiving water to 1 in 1.8. The successful application of ecotoxicological approaches enabled the assessment of cumulative effects of contaminants in influent, offering valuable insights into the sanitary sewer system under rainwater ingress.
污水溢出是一个环境问题，因为它们有可能引入污染物，从而对下游水生生态系统造成不利影响。由于这些溢出物可能发生在降雨事件期间，因此雨水从流入和渗透进入污水管的进水对污水管中未经处理的原始废水（进水）的影响是一个关键因素，会影响污染物的稀释和毒性。澳大利亚大悉尼地区的葡萄园污水输送管被选为卫生（与雨水分开）污水系统和雨天溢流（WWO）的生态毒理学研究对象。采集了三个进水样本，分别代表干天（DW）、中期雨天（IWW）和雨天（WW）。此外，还在 Vineyard Creek 下游采集了一个受纳水体样本（WW-DS），与 WWO 同时进行。我们采用直接毒性评估（DTA）和毒性识别评估（TIE）方法，全面了解雨水进入污水管对进水的影响的性质和程度。三种标准的生态毒理学模式生物，一种微藻，普通小球藻（Chlorella vulgaris）、水蚤（Ceriodaphnia dubia）和摇蚊幼虫（Chironomus tepperi）被用于急性和慢性测试。研究结果表明，存在不同的毒性反应，与干天进水样本相比，雨天进水样本的毒性较低。在干天，氨和金属被确定为观察到的毒性的贡献物，但在雨天，随着雨水的进入和在受纳水体中的进一步稀释，这种风险得到了缓解。基于毒性数据，进水的稀释度可将对 C. vulgaris 和 C. dubia 的影响降至最低，范围从 DW 中的 1:12 到 WW 中的 1:2.8，在受纳水体中进一步降至 1:1.8。生态毒理学方法的成功应用使我们能够评估进水污染物的累积效应，为雨水进入下的卫生污水系统提供了有价值的见解。
