Recycled water for heavy industry and preventing sea water intrusion

Hydrogeology

Australian Water Recycling Centre of Excellence

RP-ID  :  EP155284

学科分类：地球科学(综合)

澳大利亚|英语

来源: CSIRO Research Publications Repository

【 摘 要 】

This investigation of the feasibility of using managed aquifer recharge of treated wastewater to augment non-potable water supplies for heavy industry at Kwinana arose out of several issues:•A history of gradually falling groundwater levels and increasing seawater intrusion, both of which were increasing concerns about the ability of the unconfined Superficial Aquifer to continue to met most of the current industry needs for cooling and process water.•A lack of available groundwater for new industry in the Kwinana Industrial Area and projections of increasing industrial demands would result in an increasing gap between water supplies and demands.•The nearby increasingly abundance of often highly treated wastewater •Several investigation of managed aquifer recharge which had improved the understanding of concerns related to managed aquifer recharge using treated wastewater; namely wastewater quality, groundwater contamination, clogging,preferred pathway flow in limestone aquifers and cost relative to alternative supply options.•A long history of apparent safe disposal of treated wastewater to land at wastewater treatment plants which lack an ocean outfall; rivers not being a feasible solution in south-western Australia.The investigation reached the following main conclusions:1.Managed aquifer recharge appears to be a cost-effective future non-potable water source for heavy industry in the Kwinana Industrial Area under the assumptions used in this investigation, including those about the management of risks associated with affecting contaminated sites and discharge of nitrogen to Cockburn Sound2.Discharging treated wastewater to the Superficial Aquifer at the Kwinana WWTP appears to have helped save up-gradient Spectacles wetlands from drying as most other wetlands in the same chain have in recent decades. There is no evidence that the treated wastewater has contaminated the wetlands or down gradient groundwater which has flowed through the industrial area and discharges into Cockburn Sound. Recent upgrades to the WWTP now produce lower total nitrogen concentration water than comes from mineralising of the peat in the wetland base. 3.Risks and associated management costs area associated with the following assumptions and site conditions; a.The degree of additional treatment the treated wastewater requires to remove solids (if added through galleries) or nitrogen (if loads pose a risk to downstream wetlands and Cockburn Soundb.Whether MAR water mobilises or interacts with contaminated site water in a negative or positive way (e.g. by enabling more rapid reclamation)c.The fate of added water in terms of mixing with ambient groundwater, uptake in bores or expression at the surface in wetlands or the Sound. d.Whether all added MAR water can be used or a proportion needs to be retained for environmental purposes in a drying climatee.How well MAR water is at reversing seawater intrusion.The project results support a number of prior investigations in terms of groundwater responses to MAR, flow rates through the aquifer, discharge to the Sound and nitrogen loads. However there remain areas requiring site-specific investigations to test the conclusions. One investigation already underway on the importance of groundwater nitrogen loads compared with other sources of nitrogen in the water column (including bottom sediments) and whether nitrogen levels are no longer affecting water quality and seagrass health.