Impact of water source management practices in residential areas on sewer networks – a review

Abstract

Prolonged drought which is occurred everywhere around the world has caused water shortages, leading many countries to consider more sustainable practices which are called Source Management Practices (SMPs) to ensure water availability for the future. SMPs include the practices of water use reduction, potable water substitution and wastewater volume reduction such as water demand management, rainwater harvesting, greywater recycling and sewer mining. Besides the well known advantages from SMPs, however they also contribute to the alteration of wastewater characteristics which finally affecting the process in downstream infrastructure such as sewerage networks. Several studies have shown that the implementation of SMPs decreases the wastewater flow, whilst increasing its strength. High strength wastewater can cause sewer problems such as sewer blockage, odour and corrosion. Yet, not all SMPs and their impact on existing sewer networks have been investigated. Therefore, this study reviews some examples of four common SMPs, the wastewater characteristics and the physical and biochemical transformation processes in sewer and the problems that might caused by them and at last, the potential impacts of those SMPs on wastewater characteristics and sewer networks are discussed. This paper provides sewer system managers with an overview of potential impacts on the sewer network due to the implementation of some SMPs. Potential research opportunities for the impact of SMPs on existing sewers are also identified.

An Overview of Hybrid Water Supply Systems in the Context of Urban Water Management: Challenges and Opportunities

“…For instance, as water saving through recycling is encouraged by adopting grey water reuse, dual piping systems and sewer mining, the volume of wastewater may decrease, but this could lead to an increasing in the concentration of key contaminants [24]. Increased concentration of contaminants in wastewater has been known to cause sewer problems, such as sewer blockage, odor and corrosion [35]. Therefore, whilst the investment in decentralized water system technologies can be warranted for developments in growth areas of cities, assessing the impacts of decentralized systems on the existing developments remains challenging due to the lack of understanding of the interaction between decentralized and centralized systems [35,36].…”

“…Increased concentration of contaminants in wastewater has been known to cause sewer problems, such as sewer blockage, odor and corrosion [35]. Therefore, whilst the investment in decentralized water system technologies can be warranted for developments in growth areas of cities, assessing the impacts of decentralized systems on the existing developments remains challenging due to the lack of understanding of the interaction between decentralized and centralized systems [35,36]. Further adoption of the decentralized systems has thus far been limited to demonstration projects [37].…”

“…It can alter the hydraulic radius of the pipe changing the self-cleansing velocity requirement for the pipe [51]. Hence, if only the water is intercepted and the residuals are discharged back to the sewerage networks, there will be a potential for frequent sewer blockage [35]. Further, if recycling of such water is for household non-potable use, then a potential drawback is the cost of establishing second system of household plumbing with safeguard against cross-connection [52].…”

“…The use of tanks to harvest and store rainwater also has the potential to restore some aspects of pre-development flow regimes in receiving water [77]. The use of rainwater harvesting is also beneficial to sewers and improves wastewater treatment in the case of combined sewer networks [35,63,70]. An additional benefit of the use of rainwater tanks to supplement the existing water supply is to reduce localized urban flooding, improve stormwater quality (as these pollutants will remain in the tank) and minimize influx of stormwater into the sewer system [78,79].…”

“…But, wastewater from rainwater harvesting has higher level of metal content (lead and iron) [81], which may react with dissolved sulfide to form metal sulfide precipitates and can cause corrosion in the pipes [35]. Also, there is difficulty in managing rainwater tanks as currently there is no mechanism in place to make sure that the household rainwater collection systems are maintained and in a good condition [82].…”