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The impact of climate variability on water demand and availability in drylands is substantial. Establishing methods to analyse precipitation (P) and evapotranspiration data sets may generate useful tools that assist in drought recognition and regional variations therein. The authors developed an index that simultaneous integrates both these variables in climate variability analysis. This study proposes the alpha and normalised forms of the reconnaissance drought index (RDI) as a single climatic index for the recognition of geographical areas with differing drought characteristics and potential weather variability. The prime application is that the RDI combines in a single index both P and potential evapotranspiration. A more consistent trend of climate variability can be identified by applying time series of different durations of RDI compared to using time series of P and potential evapotranspiration separately. The researchers explore this approach using meteorological data form 24 locations representing arid, semi-arid (Mediterranean (MD), tropical (TR), continental (CN)), and humid climatic conditions. The method is then tested through application to the semi-arid Lower Zab River basin (LZRB) in Iran and Iraq. Findings show that many regions such as the LZRB will face major droughts, indicating that there is an urgent requirement to advance water management strategies. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to recommend a rapid conceptual classification model for Sustainable Flood Retention Basins (SFRB) used to control runoff in a temperate climate. An SFRB is an aesthetically pleasing retention basin predominantly used for flood protection adhering to sustainable drainage and best management practices. The classification model was developed on the basis of a database of 141 SFRB using the River Rhine catchment in Baden (part of Baden-Württemberg, Germany) as a case study. It is based on an agglomerative cluster analysis and is intended to be used by engineers and scientists to adequately classify the following different types of SFRB: Hydraulic Flood Retention Basin, Traditional Flood Retention Basin, Sustainable Flood Retention Wetland, Aesthetic Flood Retention Wetland, Integrated Flood Retention Wetland and Natural Flood Retention Wetland. The selection of classification variables was supported by a principal component analysis. The identification of SFRB in the data set was based on a Ward cluster analysis of 34 weighted classification variables. Scoring tables were defined to enable the assignment of the six SFRB definitions to retention basins in the data set. The efficiency of these tables was based on a scoring system which gave the conceptual model for the example case study sites an overall efficiency of approximately 60% (as opposed to 17% by chance). This conceptual classification model should be utilized to improve communication by providing definitions for SFRB types. The classification definitions are likely to be applicable for other regions with both temperate oceanic and temperate continental climates. [Copyright &y& Elsevier]

Water purification is one of the most essential services provided by wetlands. A lot of concerns regarding wetlands subjected to climate change relate to their susceptibility to hydrological change and the increase in temperature as a result of global warming. A warmer condition may accelerate the rate of decomposition and release of nutrients, which can be exported downstream and cause serious ecological challenges; e.g., eutrophication and acidification. The aim of this study is to investigate the effect of climate change on water quality in peatland and constructed wetland ecosystems subject to water level management. For this purpose, the authors simulated the current climate scenario base on the database from Malmö station (Scania, Sweden) for 2016 and 2017 as well as the future climate scenarios for the last 30 years of the century based on the Representative Concentration Pathway (RCP) and different regional climate models (RCM) for a region wider than Scania County. For future climate change, the authors simulated low (RCP 2.6), moderate (RCP 4.5) and extreme (RCP 8.5) climate scenarios. All simulations were conducted within climate chambers for experimental peatland and constructed wetland mesocosms. Our results demonstrate that the effect of climate scenario is significantly different for peatlands and constructed wetlands (interactive effect) for the combined chemical variables. The warmest climate scenario RCP 8.5 is linked to a higher water purification function for constructed wetlands, but to a lower water purification function and a subsequent deterioration of peatland water qualities, even if subjected to water level management. The explanation for the different response of constructed wetlands and peatlands to climate change could be due to the fact that the substrate in the constructed wetland mesocosms and peatlands was different in terms of the organic matter quality and quantity. The utilization of nutrients by the plants and microbial community readily exceed the mineralization under a limited nutrient content (as we had in constructed wetland) when the temperature rises. However, concerning the extreme scenario RCP 8.5, the peatlands have shown a tendency to have reverse processes. [Display omitted] • The climate scenarios have a significant effect on NH 4 –N, DOC, DO & TSS. • The wetland type has a significant effect on all measured physiochemical variables. • Significant interactive effect of climate scenario & wetland type on TP, NH 4 –N & COD. • RCP 8.5: High temperature deteriorates the water quality of the peatland outflow. • RCP 8.5: High temperature improves the constructed wetland outflow water quality. [ABSTRACT FROM AUTHOR]

In developing countries, there is often a lack of a comprehensive data set that support s the development of coherent policies on resource recovery from wastewater treatment. This paper aims to contribute to the elaboration of resource recovery projects by providing accurate and updated data from wastewater treatment plants such as those located in the region of the Macrometropolis of Sao Paulo. The authors discuss possibilities of improvement of resource recovery for this illustrative example. Comprehensive analyses were performed based on data from 143 municipal wastewater treatment plants to understand the situation regarding resource recovery implementation in this region. The results show that just 26% of the plants perform at least one resource recovery practice. The predominant resource recovery practice is internal water reuse, and recovery is concentrated more in large plants than in medium and small ones. The sludge is disposed in landfills except for three plants, which perform sludge recycling for compost. Some plant managers reported interest in recovering energy from biogas, in expanding water reuse and in recovering sludge for fertilizer production or for building materials. Several aspects that have been regarded as relevant to the implementation of resource recovery processes in previous literature are discussed, such as the size of the plant, related legislation as well as treatment technologies and configurations. Finally, the authors propose a generic framework with several steps that can help to achieve resource recovery implementation. Therefore, the results can provide support for planning of resource recovery projects for large cities in developing countries. Image 1 • Megacities in developing countries face severe water and sanitation challenges. • Reliable data for resource recovery plans of wastewater treatment plants are rare. • A survey collected data from 143 plants for comparison with the literature. • Barriers and opportunities for resource recovery in Sao Paulo were identified. • The proposed framework facilitates planning of future resource recovery projects. [ABSTRACT FROM AUTHOR]

The aim of this paper is to provide guidance in selecting phosphorus recovery options within the municipal wastewater treatment sector regarding developing countries. This critical review includes a brief contextualization of the resource-oriented sanitation paradigm, the discussion of processes for phosphorus recovery based on methods at full-scale, pilot-scale and laboratory-scale, and a concise discussion of the environmental impacts and benefits associated with phosphorus recovery strategies. Finally, the main challenges related to the implementation of resource recovery strategies, especially for phosphorous, were identified and discussed. According to the results, some of the main drivers for phosphorus recovery are the limited availability of phosphorus, increasing cost of phosphate fertilizers and reduction of maintenance costs. Currently, most of the operational processes are based on crystallization or precipitation from the digester supernatant. Struvite is the most common recovered product. The recovery rate of phosphorus from the liquid phase is lower (10–60% from wastewater treatment plant influent), than from sludge (35–70%) and from sludge ashes (70–98%). Phosphorus recovery remains challenging, and some barriers identified were the integration between stakeholders and institutions, public policies and regulations as well as public acceptance and economic feasibility. In developing countries, the implementation of nutrient recovery systems is challenging, because the main concern is on the expansion of sanitation coverage. Resource recovery approaches can provide benefits beyond the wastewater treatment sector, not only improving the sustainability of wastewater treatment operations, but generating revenue for the utility provider. Image 107187 • Phosphorus recovery provides several environmental, social and economic benefits. • Resource scarcity and high fertilizer costs are drivers for phosphorus recovery. • High energy demand and contamination are linked to some recovery technologies. • Other resources can be recovered together with phosphorus to increase added value. • Sewage sludge and ash have higher phosphorus recovery rates than the liquid phase. [ABSTRACT FROM AUTHOR]

Precipitated sludge (ochre) obtained from a mine water treatment plant was considered as an adsorbent substance for pollutants, since ochre is relatively free from problematic levels of toxic elements, which could impair on the quality of water to be treated. Artificially created ochre pellets from mixing Portland cement with raw ochre sludge were utilised to remediate either high (HC) or low (LC) contaminated synthetic greywater (SGW) in mesocosm–scale stabilisation ponds at 2–day and 7–day contact times under real weather conditions in Salford. After a specific retention time, treated SGW was agitated before sampling to evaluate pollutant removal mechanisms (other than sedimentation) such as adsorption by ochre pellets, before replacing the treated water with new inflow SGW. The results showed that cement–ochre pellets have a high ability to adsorb ortho–phosphate–phosphorous (PO 4 –P) significantly (p < 0.05) by 70.7% and 56.0% at 7–day contact time for HC–SGW and LC–SGW, respectively. After the experiment, an analysis revealed that elements such as boron (B), cadmium (Cd), magnesium (Mg), manganese (Mn), nickel (Ni) and zinc (Zn) accumulated significantly (p < 0.05) within the ochre pellets. The notable accumulation of Cd within ochre pellets reflects the significant (p < 0.05) remediation of greywater during the first 35 and 20 successive times of treatment for HC–SGW at 2– and 7–day contact times, respectively. Cadmium was still adsorbed significantly (p < 0.05) during the treatment of LC–SGW. However, the calcium (Ca) content decreased significantly (p < 0.05) within ochre pellets treating both types of greywaters due to mobilisation. The corresponding increases of Ca in greywater were significant (p < 0.05). [ABSTRACT FROM AUTHOR]

Severe rainfall events have become increasingly common in Europe. Flood defence engineering works are highly capital intensive and can be limited by land availability, leaving land and communities exposed to repeated flooding. Any adaptive drainage structure must have engineered inlets and outlets that control the water level and the rate of release. In Scotland, there are a relatively high number of drinking water reservoirs (operated by Scottish Water), which fall within this defined category and could contribute to flood management control. Reducing the rate of runoff from the upper reaches of a catchment will reduce the volume and peak flows of flood events downstream, thus allowing flood defences to be reduced in size, decreasing the corresponding capital costs. A database of retention basins with flood control potential has been developed for Scotland. The research shows that the majority of small and former drinking water reservoirs are kept full and their spillways are continuously in operation. Utilising some of the available capacity to contribute to flood control could reduce the costs of complying with the EU Flood Directive. Furthermore, the application of a previously developed classification model for Baden in Germany for the Scottish data set showed a lower diversity for basins in Scotland due to less developed infrastructure. The principle value of this approach is a clear and unambiguous categorisation, based on standard variables, which can help to promote communication and understanding between stakeholders. [Copyright &y& Elsevier]

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change. [Display omitted] • Drought might shift the role of wetlands from carbon sinks to carbon sources. • Higher temperatures and more rain can maintain the role of wetlands as carbon sinks. • There might be a critical water level at which a wetland can preserve its services. • A new framework for conducting wetland mesocosm experiments has been proposed. • The proposed experiment allows for testing of dynamic process-based model results. [ABSTRACT FROM AUTHOR]

Attapulgite (or palygorskite) is a magnesium aluminium phyllosilicate. Modified attapulgite-supported nanoscale zero-valent iron (NZVI) was created by a liquid-phase reduction method and then applied for nitrate-nitrogen (NO 3 -N) removal (transformation) in simulated groundwater. Nanoscale zero-valent iron was sufficiently dispersed on the surface of thermally modified attapulgite. The NO 3 -N removal efficiency reached up to approximately 83.8% with an initial pH values of 7.0. The corresponding thermally modified attapulgite-supported nanoscale zero-valent iron (TATP-NZVI) and NO 3 -N concentrations were 2.0 g/L and 20 mg/L respectively. Moreover, 72.1% of the water column NO 3 -N was converted to ammonium-nitrogen (NH 4 -N) within 6 h. The influence of environmental boundary conditions including dissolved oxygen (DO) concentration, light illumination and water temperature on NO 3 -N removal was also investigated with batch experiments. The results indicated that the DO concentration greatly impacted on NO 3 -N removal in the TATP-NZVI-contained solution, and the NO 3 -N removal efficiencies were 58.5% and 83.3% with the corresponding DO concentrations of 9.0 and 0.3 mg/L after 6 h of treatment, respectively. Compared to DO concentrations, no significant (p > 0.05) effect of light illumination on NO 3 -N removal and NH 4 -N generation was detected. The water temperature also has great importance concerning NO 3 -N reduction, and the removal efficiency of NO 3 -N at 25 °C was 1.25 times than that at 15 °C. For groundwater, therefore, environmental factors such as water temperature, anaerobic conditions and darkness could influence the NO 3 -N removal efficiency when TATP-NZVI is present. This study also demonstrated that TATP-NZVI has the potential to be developed as a suitable material for direct remediation of NO 3 -N-contaminated groundwater. [ABSTRACT FROM AUTHOR]