Develop a multi-functional green pervious concrete (MGPC) pavement with polycyclic aromatic hydrocarbons (PAHs) removal function.

Stormwater runoff induced Polycyclic Aromatic Hydrocarbons (PAHs) contaminant increasingly imperils the groundwater quality and the sustainable development of human society due to the potential carcinogenic risks. Pavement can be considered as the first line of defense for contaminant removal of the stormwater runoff. New construction materials with stormwater runoff quantity and quality control are in urgent demand for updating the existing pavement system. An innovative material called Multi-functional Green Pervious Concrete (MGPC) was developed in the department of Civil and Environmental Engineering at University of Louisville. This material uses organoclay as the amendment to enhance the PAHs removal capacity of conventional pervious concrete. The objective of this study is to evaluate the potential implementation of MGPC as a pavement material with the groundwater contamination remediation functions. The study was performed in five stages. First, The PAHs remediation function of MGPC was tested by introducing organoclay [bis (hydrogenated tallow alkyl) dimethyl ammonium modified montmorillonite] to the conventional pervious concrete. After test and verification, the mix proportion of MGPC was designed to meet the compressive strength and hydraulic conductivity requirements of pervious concrete. A small amount of organoclay addition was found not to adversely affect the compressive strength and hydraulic conductivity of MGPC. The preliminary study of the PAHs removal functions of MGPC was conducted in stage two. The isothermal batch sorption test was conducted to quantify the sorption capacity of the organoclay modified cement paste, and the column test was performed to investigate the transport mechanism and retardation behavior of PAHs in MGPC. It was found that the developed MGPC with a small addition of organoclay could substantially remove PAHs contaminants and it also has much stronger adsorption and retardation capacity than the conventional pervious concrete. In stage three, a series of comprehensive laboratory-scale tests were conducted to examine the effectiveness of stormwater induced PAHs removal by using the MGPC pavement. The results indicated that the initial concentrations of the PAHs and the flow rates would impact the removal efficiency of MGPC. The tests showed that the MGPC still maintained considerable sorption capacity after 50 PAHs sorption and desorption cycles. An ideal site under steady-state groundwater conditions was generated to simulate the long-term performance of MGPC on PAHs removal by using the finite element method in stage four. The laboratory experiments were used to determine the physicochemical parameters of MGPC, and three sorption isothermal models (linear, Freundlich and Langmuir) were fitted to the sorption test data. The computer simulation revealed that the MGPC had significant remediation efficiency on the PAHs contaminant. Other than the material properties of MGPC, the efficiency of contaminant remediation of MGPC was also found to be influenced by the permeability of the subbase and the initial concentration of PAHs. It was also found that the linear isotherm model would overestimate the removal efficiency of PAHs with higher concentration sources. At last final fifth stage, a Pavement Environment and Performance Index (PEPI) was proposed to evaluate the environmental impacts of three different types of pavements (impervious concrete, conventional pervious concrete, and MGPC). The data from experiments and the Environmental Footprint Database was used to calculate the PEPI. Based on the Life Cycle Assessment (LCA) results, it was found that the MGPC pavement was much more environmentally friendly with relatively lower greenhouse gas emissions and energy consumption, and better environmental performance comparing with the other two types of pavements

SALT WATER INTRUSION IN WATER DISTRIBUTION SYSTEMS: ANALYSIS, SOLUTION, AND ECO-EFFICIENCY

Since many water distribution systems (WDSs) experience saltwater intrusion, system behavior during saltwater intrusion is important. An alternative to the currently accepted WDS decontamination method of hydrant flushing is needed since during the current procedure all contaminated water is discharged to the surroundings which imposes environmental impacts. Hence, this research was conducted to study salt spread in different WDSs and to seek an alternative to hydrant flushing as a way of WDS decontamination. First, salt contamination was modelled in real water system models to document the salt spread. It was found that (1) if salt enters as a short pulse, it may contaminate different parts at different times; (2) in a multi-reservoir system if any reservoir remains fresh during a salt contamination event, contamination might take a longer time to reach the system edges; and (3) for all system types, time to clear the system from salt contamination is linearly correlated to the rate of salt entry at the source. Second, the performance of a containment pond was evaluated as an alternative to hydrant flushing, in which a pond lined with impermeable material will be constructed in a suitable place. Network modeling was performed, and it was found that (1) a containment pond can be a better option for WDS decontamination from an environmental viewpoint; (2) flushing only into the containment pond cannot clear all areas of the system; and (3) for some systems, some pond locations might be better from an economic perspective, while other locations will be better environmentally. A containment pond also has some environmental impact since the pond requires initial construction. Also, the decontamination time depends on the decontamination option chosen. Finally, a life cycle assessment study was performed using SimaPro for both the decontamination options and the impacts were assessed using IMPACT 2002+. The results show that (1) a containment pond can reduce the environmental impact caused during hydrant flushing alone; (2) using a containment pond can be more effective in an urban area; and (3) the time needed for the decontamination and the area exposed to contaminated water significantly affect environmental impact

Integrated Environmental Modelling Framework for Cumulative Effects Assessment

Global warming and population growth have resulted in an increase in the intensity of natural and anthropogenic stressors. Investigating the complex nature of environmental problems requires the integration of different environmental processes across major components of the environment, including water, climate, ecology, air, and land. Cumulative effects assessment (CEA) not only includes analyzing and modeling environmental changes, but also supports planning alternatives that promote environmental monitoring and management. Disjointed and narrowly focused environmental management approaches have proved dissatisfactory. The adoption of integrated modelling approaches has sparked interests in the development of frameworks which may be used to investigate the processes of individual environmental component and the ways they interact with each other. Integrated modelling systems and frameworks are often the only way to take into account the important environmental processes and interactions, relevant spatial and temporal scales, and feedback mechanisms of complex systems for CEA. This book examines the ways in which interactions and relationships between environmental components are understood, paying special attention to climate, land, water quantity and quality, and both anthropogenic and natural stressors. It reviews modelling approaches for each component and reviews existing integrated modelling systems for CEA. Finally, it proposes an integrated modelling framework and provides perspectives on future research avenues for cumulative effects assessment

The capacity of the Cape Flats aquifer and its role in water sensitive urban design in Cape Town

There is growing concern that South Africa's urban centres are becoming increasingly vulnerable to water scarcity due to stressed surface water resources, rapid urbanisation, climate change and increasing demand for water. Furthermore, South Africa is a water-stressed country with much of its surface water resources already allocated to meet current demands. Therefore, in order to meet the future urban water supply requirements, countries like South Africa will need to consider alternative forms of water management that focus on moving towards sustainability in urban water management. WSUD is one such approach that aims to prioritise the value of all urban water resources through reuse and conservation strategies, and the diversification of supply sources. This study investigates the capacity of the Cape Flats Aquifer (CFA), assessing the feasibility of implementing Managed Aquifer Recharge (MAR) as a strategy for flood prevention and supplementing urban water supply. The implementation of MAR on the CFA aims to facilitate the transition towards sustainable urban water management through the application Water Sensitive Urban Design (WSUD) principles. The fully-integrated MIKE SHE model was used to simulated the hydrological and hydrogeological processes of the CFA in Cape Town at a regional-scale. Using the results of the regional-scale model, four sites were selected for more detailed scenario modelling at a local-scale. Several MAR scenarios were simulated to evaluate the aquifer's response to artificial recharge and abstraction under MAR conditions. The first objective was to evaluate the feasibility of summer abstractions as a flood mitigation strategy at two sites on the Cape Flats prone to winter groundwater flooding, viz. Sweet Home and Graveyard Pond informal settlements. The second objective of the study was to assess the storage potential and feasibility of MAR at two sites in the south of the Cape Flats, at Philippi and Mitchells Plain. In addition, the migration of solute pollutants from the injected or infiltrated stormwater was simulated and climate change simulations were also undertaken to account for potential fluctuations in rainfall and temperature under climate change conditions. The results indicated that flood mitigation on the Cape Flats was possible and was likely to be most feasible at the Graveyard Pond site. The flood mitigation scenarios did indicate a potential risk to local groundwater dependent ecosystems, particularly at the Sweet Home site. Yet, it was shown that a reduction in local groundwater levels may have ecological benefits as many of the naturally occurring wetlands on the Cape Flats are seasonal, where distinct saturated and unsaturated conditions are required. Furthermore, MAR was shown to improve the yield of wellfields at Philippi and Mitchells Plain through the artificial recharge of stormwater while also reducing the risk of seawater intrusion. MAR was shown to provide a valuable means of increasing groundwater storage, improving the supply potential of the CFA for water supply while aiding the prevention or mitigation of the seasonal flooding that occurs on the Cape Flats. Furthermore, the case was made that MAR is an important strategy to assist the City of Cape Town in achieving its WSUD objectives. MAR and groundwater considerations, in general, are essential for the successful implementation of WSUD, without which, there is an increased risk of overlooking or degrading urban groundwater resources. The findings of this study resulted in a number of recommendation to urban water resources managers, planners and policy makers. First, MAR is an important means for Cape Town to move towards becoming a truly water sensitive city. This study indicated that the CFA should be incorporated as an additional source of water supply for Cape Town especially considering the recent drought conditions and due to its ability for the seasonal storage of water, this would improve the city's resilience to climate change. Furthermore, it was recommended that the application of MAR on the CFA could also be used to reduce groundwater related flooding on the Cape Flats. Second, it was emphasised that urban planning, using WSUD principles is essential for the protection of the resource potential of the CFA. Finally, for the implementation of WSUD and MAR to be successful, there needs to be appropriate policy development alongside the implementation of these strategies to ensure they are achieving their initial objectives and are not causing detriment to the aquifer

SMaRT-OnlineWDN: A Franco-German Project For The Online Security Management Of Water Distribution Networks

Water Distribution Networks (WDNs) are critical infrastructures that are exposed to deliberate or accidental chemical, biological or radioactive contamination which need to be detected in due time. However, until now, no monitoring system is capable of protecting a WDN in real time. Powerful online sensor systems are currently developed and the prototypes are able to detect a small change in water quality. In the immediate future, water service utilities will install their networks with water quantity and water quality sensors. For taking appropriate decisions and countermeasures, WDN operators will need to dispose of: 1) a fast and reliable detection of abnormal events in the WDNs; 2) reliable online models both for the hydraulics and water quality predictions; 3) methods for contaminant source identification backtracking from the data history. Actually, in general none of these issues (1) – (3) are available at the water suppliers. Consequently, the main objective of the project SMaRT-OnlineWDN is the development of an online security management toolkit for WDNs that is based on sensor measurements of water quality as well as water quantity. Its main innovations are the detection of abnormal events with a binary classifier of high accuracy and the generation of real-time, reliable (i) flow and pressure predictions, (ii) water quality indicator predictions of the whole water network. Detailed information regarding contamination sources (localization and intensity) will be explored by means of the online running model, which is automatically calibrated to the measured sensor data. Its field of application ranges from the detection of deliberate contamination including source identification and decision support for effective countermeasures to improved operation and control of a WDN under normal and abnormal conditions (dual benefit).In this project, the technical research work is completed with a sociological, economical and management analysis

A Literature Review of Wetland Treatment Systems Used to Treat Runoff Mixtures Containing Antibiotics and Pesticides from Urban and Agricultural Landscapes

Wetland treatment systems are used extensively across the world to mitigate surface runoff. While wetland treatment for nitrogen mitigation has been comprehensively reviewed, the implications of common-use pesticides and antibiotics on nitrogen reduction remain relatively unreviewed. Therefore, this review seeks to comprehensively assess the removal of commonly used pesticides and antibiotics and their implications for nitrogen removal in wetland treatment systems receiving non-point source runoff from urban and agricultural landscapes. A total of 181 primary studies were identified spanning 37 countries. Most of the reviewed publications studied pesticides (n = 153) entering wetlands systems, while antibiotics (n = 29) had fewer publications. Even fewer publications reviewed the impact of influent mixtures on nitrogen removal processes in wetlands (n = 16). Removal efficiencies for antibiotics (35–100%), pesticides (−619–100%), and nitrate-nitrogen (−113–100%) varied widely across the studies, with pesticides and antibiotics impacting microbial communities, the presence and type of vegetation, timing, and hydrology in wetland ecosystems. However, implications for the nitrogen cycle were dependent on the specific emerging contaminant present. A significant knowledge gap remains in how wetland treatment systems are used to treat non-point source mixtures that contain nutrients, pesticides, and antibiotics, resulting in an unknown regarding nitrogen removal efficiency as runoff contaminant mixtures evolve