Wastewater irrigation: the state of play

As demand for fresh water intensifies, wastewater is frequently being seen as a valuable resource. Furthermore, wise reuse of wastewater alleviates concerns attendant with its discharge to the environment. Globally, around 20 million ha of land are irrigated with wastewater, and this is likely to increase markedly during the next few decades as water stress intensifies. In 1995, around 2.3 billion people lived in water-stressed river basins and this could increase to 3.5 billion by 2025. We review the current status of wastewater irrigation by providing an overview of the extent of the practice throughout the world and through synthesizing the current understanding of factors influencing sustainable wastewater irrigation. A theme that emerges is that wastewater irrigation is not only more common in water-stressed regions such as the Near East, but the rationale for the practice also tends to differ between the developing and developed worlds. In developing nations, the prime drivers are livelihood dependence and food security, whereas environmental agendas appear to hold greater sway in the developed world. The following were identified as areas requiring greater understanding for the long-term sustainability of wastewater irrigation: (i) accumulation of bioavailable forms of heavy metals in soils, (ii) environmental fate of organics in wastewater-irrigated soils, (iii) influence of reuse schemes on catchment hydrology, including transport of salt loads, (iv) risk models for helminth infections (pertinent to developing nations), (v) microbiological contamination risks for aquifers and surface waters, (vi) transfer efficiencies of chemical contaminants from soil to plants, (vii) health effects of chronic exposure to chemical contaminants, and (viii) strategies for engaging the public.<br /

Melbourne water open data portal

This data allows the user to browse&nbsp;Melbourne Water land and view the estimated availability of Melbourne Water land for a community project

Interim Report: Water for Our Future

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The potential to retrofit sustainable drainage systems to address combined sewer overflow discharges in the Thames Tideway catchment

Experience of retrofitting sustainable drainage systems (SuDS) in the United Kingdom is limited, and there are no well-established procedures for evaluating the feasibility, value or cost-effectiveness of doing this, particularly at the catchment scale. This paper demonstrates a two-phase process for evaluating the potential to retrofit SuDS to address combined sewer discharges in three subcatchments within the Thames Tideway catchment of London. The first phase evaluates what might be achieved with various levels of disconnection (‘global’ disconnection scenarios) using hydraulic models, while the second phase considers how disconnection might practically be achieved. High levels of disconnection are technically possible but practicably difficult. In selected cases, and with aggressive implementation of SuDS, combined sewer overflow CSO discharges could potentially be eliminated or reduced to acceptable levels without the need for any modifications to underground assets. However, retrofit SuDS could not eliminate the requirement for some form of sewer modification in any subcatchments

Contrasting patterns of leaf solute accumulation and salt adaptation in four phreatophytic desert plants in a hyperarid desert with saline groundwater

The seasonal variation of leaf solutes was investigated in four perennial phreatophytes in the natural vegetation surrounding a river oasis in the Chinese Taklamakan desert in order to elucidate their adaptation to saline groundwater. Leaves of the herbaceous perennial legume Alhagi sparsifolia, the poplar tree Populus euphratica, the salt cedar Tamarix ramosissima, and the C-4 shrub Calligonum caput-medusae were collected at the end of each month during the growing season 1999 and analysed for cation, anion, organic acid, carbohydrate, glycinebetaine, and proline concentrations. The species revealed considerable differences in the foliar solute composition and their seasonal variation. Tamarix had high foliar mineral salt concentrations throughout the season but excreted the accumulated salts via salt glands. The three other species showed different degrees of ion regulation and ion selectivity. Calligonum had generally very low mineral ion concentrations, tolerated moderate Cl- concentrations and excluded Na+. Populus effectively excluded Cl- from its leaves but Na+ and total solute concentrations increased towards the end of the season which lead to K:Na ratio smaller than one in October. Alhagi showed the highest degree of ion selectivity by excluding Na+ but accumulating Ca2+ in its leaves. Mineral salt composition of xylemsap in Alhagi and Calligonian indicated that both species showed a similar degree of ion selectivity in the roots and that ion retransloction is probably another important mechanism to maintain low salt concentrations in the leaf. The cyclitols chiro-inositol and pinitol were the major compatible solutes in the plants and N-containing solutes like proline or glycinebetaine occurred only in minor concentrations or were absent, respectively. All plant species were well adapted to the moderate salinity of the NaCl dominated groundwater and no signs of salt related drought stress, ion toxicity or nutrient imbalance were observed. (C) 2003 Elsevier Ltd. All rights reserved