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Grey water footprint (GWF) accounting has previously been conducted at the global level using a bottom-up approach but lacking detailed industrial information. Here we applied a multi-region input-output approach based on the World Input-Output Database (WIOD) to quantify global GWF of 40 countries/regions with 35 economic sectors. The GWF from both the production perspective (GWFP), and the consumption perspective (GWFC) are quantified. The results show that the global GWFP/GWFC was 1507.9 km3 in 2009. Except for the “Agriculture, Hunting, Forestry and Fishing” sector, the industrial sectors with the largest GWFC were “Food, Beverages and Tobacco”, “Construction”, “Chemicals and Chemical Products”, and “Textiles and Textile Products”. The BRIC countries (Brazil, Russia, India, China) had a larger GWFP than their GWFC, which accounted for over half of global GWFP (53.6%), and their GWFP was mainly generated from the production of domestic final demand. In contrast, the OECD29 and EU27 groups of countries i.e. the country groups consisting mainly of economically advanced nations, had larger GWFC than their GWFP. Overall, the OECD29 and EU27 outsourced 134.8 km3 and 64.4 km3 of their grey water respectively, mostly to large newly advanced economies such as the BRIC group of countries, which, in turn, were collectively outsourcing 112 km3 of grey water. Quantitative approaches are thus suggested for development, aimed at shared responsibility for water pollutant discharge among poor exporters and wealthy consumers.

The increased number and capacity of municipal wastewater treatment plants (WWTPs) in China has driven the emission of methane (CH 4 ). Few studies have focused on quantification of CH 4 emissions from municipal WWTPs of different cities and analysis of socioeconomic factors influencing the quantity of emissions. Here we estimated CH 4 emissions from WWTPs in China for 229 prefectural-level cities, based on data from 2,019 working municipal WWTPs. The results show the total CH 4 emissions to be 1,169.8 thousand tons (29.2 MtCO 2 e) in 2014, which is over three times that of the municipal WWTPs in the United States in 2016. Large cities along the east coast regions had larger CH 4 emissions in absolute and per capita terms. Correlation analysis shows that cities with higher gross domestic product, household food consumption expenditure, or household consumption expenditure produced more degradable organics in wastewater, thus more CH 4 emissions. Measures to control the sources of degradable organics and regulate WWTP processes with less emission factor are key to mitigate CH 4 emissions. In addition to aerobic or anaerobic wastewater treatment systems, factors such as wastewater temperature, length of sewer, and the addition of nitrate that influencing emission factor are suggested to be involved in CH 4 emission modeling.

International audience; Water is required throughout the life-cycle processes of energy production to meet the growing energy demands in China's megacities. However, the spatially explicit impact on water scarcity both inside and outside the megacity boundaries from megacities’ energy demands remains unknown. We quantified and compared the water footprint and water scarcity footprint for final energy demand (WFE and WSFE) in China's megacities from a consumption perspective. Six acknowledged megacities, i.e. Beijing, Tianjin, Shanghai, Chongqing, Shenzhen and Guangzhou, were evaluated with an extended multi-region input–output model. The results showed that these megacities were endowed with only 2.60% of the national available water resources, but their WFE (WSFE) made up nearly 14.00% (13.50%) of the national total. The megacities located in Northern China generated a larger WSFE in their WFE than the cities in Southern China. Energy demands in these megacities were heavily dependent on scarce water sourced from beyond their administrative boundaries, together importing 84.10% of WSFE from elsewhere. Electricity demand dominated the volumetric water consumption, representing 52.00% of the WFE. The distribution was different for scarce water consumption, with coal demand generating 34.00% of total WSFE, followed by electricity (31.00%) and petroleum (26.00%). Although Northern China is faced with dire water scarcity, its scarce water is still being predominantly outsourced to support energy demands in both Northern and Southern megacities, mainly due to their coal and petroleum reserves. Location-specific pathways and foci should be applied for different megacities to decouple their energy demands and their scarce water consumption.

Biofiltration systems are a promising retrofit option for site-constrained urban areas due to the vertical arrangement of treatment stages that leads to a relatively compact footprint. Existing knowledge about the influence of their design and configuration on hydrological, stormwater pollutant removal and long-term performance is limited and this has been identified as a barrier to their widespread uptake. Long-term simulations of lined and unlined biofiltration systems in four contrasting UK climatic regimes were used to assess the influence of climate, ponding depth, biofilter to drainage area ratio and infiltration rate on hydrological performance. The results showed that local differences in climate have a significant impact on performance and that infiltration rates as low as 0·36 mm/h are not suitable for locations in the UK with high rainfall unless the biofilter to drainage area ratio is greater than 10%. However, with higher infiltration rates (72 mm/h) a biofilter occupying only 3% of the impermeable catchment area would be capable of infiltrating 97% of annual rainfall in central England. Preliminary results of adsorption and column tests to assess the effectiveness of media amendments, specifically zeolite and granular activated carbon, for dissolved copper and phosphate removal are presented in this paper.

For UK Water and Sewerage Companies (WaSCs), the capacity to innovate capital investment processes, and consequently performance outcomes is fundamental as they seek to deliberately change infrastructure to improve the sustainability of service delivery within a comparatively regulated framework. Innovation is viewed here as being either incremental or radical changes to the products (services) and processes (ways of delivering services) which are typical to the organisation (WaSCs). Product and process innovations may involve changes to some or all of technologies, organisational structure and processes, behaviour and culture, and knowledge and skills within the organisation and its supply chain. This paper sets out to provide an understanding of the factors which both enable and constrain the development and adoption of infrastructure investment process innovations in the context of water utilities concerned with water and sewerage service delivery. The paper documents the process and results from an inductive research programme of participatory action research undertaken within a large, privately owned UK WaSC to facilitate infrastructure investment process innovation. Employee narratives during the innovation process from initiation to adoption decision-making were characterised and analysed. The findings suggest that the development and adoption of asset investment process innovations tends to be skewed in favour of opportunities which align with (i) UK and European Union legislative and regulatory drivers; (ii) WaSC mission policy and goals; (iii) innovation cost advantages over a prescribed period of time; (iv) perceived risks to service provision associated with the introduction of the innovation, and; (v) the extent to which the organisational processes and cultures which act to increase the absorptive capacity of the WaSC to the proposed innovation are already functioning.

A rapidly expanding economy and increasing water demand for agricultural and industrial production is placing enormous stress on water quantity and the aquatic environment in Northern China, especially the so-called Jing-Jin-Ji (Beijing-Tianjin-Hebei) urban agglomeration, home to over 110 million people producing 10% of China's overall GDP. Several studies have focused on energy consumption, air pollution, CO 2 emissions and regional blue water footprint (WF) following release of the Jing-Jin-Ji Integration Strategy by the China government in 2013. However, a comprehensive assessment distinguishing blue, green and grey WF amongst different industrial sectors, ascertaining how WF transfers internally and beyond the region and final demand consumption is not available. We consider this to be crucial in understanding and addressing the deteriorating water situation in the Jing-Jin-Ji. In this study, we quantified the WF and virtual water flow on a sectoral basis for the year 2010 through coupling the multi-regional input-output model (MRIO) with WF assessment. The results showed that Beijing and Tianjin are net importers of green, blue and grey water from Hebei and other China provinces to support their needs. Conversely, Hebei exports all WF colors to Beijing, Tianjin and other provinces in China, and more than 60% of WF is transferred as virtual water. For the overall Jing-Jin-Ji region a small amount of blue water (2086 million m 3 ) is exported, but huge amounts of green water (15,573 million m 3 ) and grey water (30,620 million m 3 ) are outsourced. A “Virtual Water Strategy” is one measure which could alleviate water stress at the regional scale, with consideration of financial compensation from water receiving regions made to water supplying regions in the context of achieving water management targets. We also found that physical water transfer to Jing-Jin-Ji could not balance virtual blue water exports, not to mention compensating for internal water consumption. Our research suggests that a continuation of an export-based economic development model will worsen Hebei's water stress. Reducing the dependency of Hebei's sectoral economy on export of water intensive and low value added agricultural products may be one strategy to reduce the pressure on regional water resources. In addition, the Beijing-Tianjin-Hebei Integration Strategy drives industrial transfer from Beijing to Hebei resulting in the transfer of enterprises with low water utilization efficiency and producing heavy pollution. As a result, the government should consider incentivizing corporations to adopt technologies that reduce water consumption and pollution.

Rapid urbanization has resulted in often unplanned increases in population, and food demand in cities. Historically, hinterlands to these cities have acted as breadbaskets producing food to the urban residents. Accordingly, a large amount of available freshwater has been needed to support these croplands. However, the rapid expansion of cities in developing countries has significantly changed both the croplands around cities and the water demand. It is thus important to quantitatively investigate the water-food nexus of cities related to the changing hinterland agriculture. Water footprint is an indicator reflecting the human impact on water. In this study, we quantified both the blue and green water footprint of major crop products in Suzhou city, China using a bottom-up accounting method. A novel decomposition analysis was carried out with a Logarithmic Mean Divisia Index (LMDI) method to study the driving forces that changed the water footprint during the period 2001–2010. The drivers were designed to reflect the factors related to farmland, such as yield and crop area. This is different from previous decomposition analyses, which focused on economic factors such as GDP. The results show that the crop water footprint of Suzhou city has seen a general decreasing trend between 2001 and 2010. The decomposition analysis showed that the decline of crop area was the main driver that decreased the crop water footprint, followed by the virtual water content (water consumption per unit of production). In contrast the changes of crop combination and yield contributed to an increase in the crop water footprint. Although the shrink of urban croplands decreased the water footprint of crop products. Cities’ increasing demand for food will increase the crop water footprint of consumption. This will increase the dependence of cities on external water footprint of crop products (water embodied in imported crops), which may impact upon food security in cities in the long term.

Using a consumption-based Multi-Regional Input-Output (MRIO) model, we investigate the distinctive characteristics, self-efficiency or external dependency, of energy demand's water footprint in China's two biggest and fastest developing megalopolises. We find that energy demand water footprint in the Jing-Jin-Ji and the Yangtze Delta amounted to 2.41 and 9.59 billion m³of water withdrawal respectively in 2010, of which 848.06 and 973.91 million m³was consumed. Among all energy products, electricity contributed the largest share to the energy sector's water footprint in both regions. The sectoral distribution of water footprint in the upstream supply chain differed by region. Most significantly, the agricultural sector accounted for more than 30% of water consumption footprint. In addition to water used locally, final energy demands in these two regions induced external water footprint beyond their administrative boundaries. The Jing-Jin-Ji region's energy sector had a smaller water footprint compared to the water-abundant Yangtze Delta region. However, external water footprint occupied a larger proportion in the former. Such divergence can be attributed to the distinctive water endowments and water-using technologies utilized in their respective energy sectors. Bespoke urban governance and policies tailored to local resource and technology portfolios are recommended for different urban agglomeration energy and water flows.

Electricity demand in megacities may exert substantial stress on water resources, which is often expressed through the water scarcity footprint for electricity consumption (WSFE). Conversely, water scarcity may constrain electricity production, leading to increased vulnerability for megacities electricity production. The WSFE and the water related vulnerability of electricity production reflect two aspects of water-electricity conflict. This varies over time by both the amount and location of electricity production. However, no studies have conducted time-series analysis to evaluate the trends of these two indicators, both in terms of severity and spatial characteristics. Our study focused on evaluating trends in water-electricity conflict both within and beyond megacity administrative boundaries. China's four provincial-level megacities, i.e. Beijing, Tianjin, Shanghai and Chongqing, were chosen as case studies. The results show that water related vulnerability of electricity production in Tianjin, Beijing, Shanghai and Chongqing was diverse and can be classified as extreme, severe, moderate and minor, respectively. Between 2006 and 2016, the WSFE of Tianjin experienced an increasing trend, and its water related vulnerability of electricity production remained at the highest level. Beijing's WSFE has decreased, but its water related vulnerability of electricity production has increased. These differing trends highlight the need for joint reductions to both WSFE and water related vulnerability of electricity production in mitigating water-electricity conflict.

Reducing food losses (FL) is a promising way of improving food security. This is much more urgent for the developing world with a high level of food insecurity. However, driving factors contributing to the changes of FL are poorly understood. Here, we report on an investigation into the contribution of five potential driving factors to FL in Cameroon between 1994 and 2013, using a Logarithmic Mean Divisia Index (LMDI) approach. The results showed that FL in Cameroon has increased more than 4 fold during the study period. The increase of FL per unit crop production (intensity effect) contributed the most to increase FL (36.87% of the total change), followed by the increase of per capita crop consumption, i.e. supply scale effect (34.55%), population growth (26.72%), and changes of crop production structure, i.e. structure effect (5.079%). Only the dependency on self-production (self-sufficiency effect) contributed to decrease FL (3.22%).

Much attention has been paid to burden-shifting of CO2 emissions from developed regions to developing regions through trade. However, less discussed is that trade also acts as a mechanism enabling wealthy consumers to shift water quantity and quality stress to their trading partners. In this study we investigate how Shanghai, the largest mega-city in China, draws water resources from all over China and outsources its pollution through virtual quantity and quality water flows associated with trade. The results show that Shanghai’s consumption of goods and services in 2007 led to 11.6 billion m3 of freshwater consumption, 796 thousand tons of COD, and 16.2 thousand tons of NH3-N in discharged wastewater. Of this, 79% of freshwater consumption, 82.9% of COD and 82.5% of NH3-N occurred in other Chinese Provinces which provide goods and services to Shanghai. Thirteen Provinces with severe and extreme water quantity stress accounted for 60% of net virtual water import to Shanghai, while 19 Provinces experiencing water quality stress endured 79% of net COD outsourcing and 75.5% of net NH3-N outsourcing from Shanghai. In accordance with the three ‘redlines’ recently put forward by the Chinese central government to control water pollution and cap total water use in all provinces, we suggest that Shanghai should share its responsibility for reducing water quantity and quality stress in its trading partners through taking measures at provincial, industrial and consumer levels. In the meantime, Shanghai needs to enhance demand side management by promoting low water intensity consumption.

The implications of climate change coupled with anthropogenic activity on water resources have caused great concern, particularly in areas vulnerable to water stress such as sub-Saharan Africa. We focused on the future magnitude of food loss (FL) in African regions, using an ARIMAX model to fit and forecast roots & tubers (R&T) losses of five major crops cultivated in Africa regions, including cassava, potato, sweet potato, yam, and “other” roots & tubers. The forecast was done up to 2025 under the influence of five exogenous variables, namely, gross domestic product, harvested area, precipitation, temperature, and food production. In addition, the future crop water requirement (CWR) of production under climatic variables, and the associated water loss embodied in FL were quantified by means of CROPWAT 8.0. Our findings showed that in 2025 the magnitude of FL is expected to increase by 19.06%, 104.78%, and 27.72% at 2013 levels for East Africa, Middle, and West Africa, respectively. Under future climate the CWR of the selected crops is expected to be higher in West Africa (1790.24 m3/tonne), than in East (989.03 m3/tonne), and Middle Africa (903.64 m3/tonne). The future water loss embodied in FL is expected to be 114.37, 112.80, and 12.06 m3/cap/yr for the West, Middle, and East Africa regions, respectively. Our results show that measures aimed at preventing FL will also alleviate pressure on available water resources.

The water resource networks that provide water for urban consumption consists not only of physical water supply, but also water embodied in imported goods and services i.e. virtual water supply or external water footprint. However, it remains unknown that if relying on external water footprint will increase or decrease the vulnerability of cities’ water resource networks. Here, we evaluate the vulnerability of urban water resource networks for China's six megacities i.e. Beijing, Tianjin, Shanghai, Chongqing, Guangzhou, and Shenzhen. The vulnerability index was developed through combining a refined multi-region input-output table with both water footprint and water scarcity footprint analysis. The results showed that megacities need to import large volumes of virtual water embodied in food related sectors to balance their physical water shortages. The external blue water footprint (BWF) of the six megacities accounted for 80.7% of their total BWF, and was almost twice their physical water supply. The large share of external BWF helped Beijing, Tianjin, and Shanghai, which suffer extreme water stress in their urban areas, to decrease their total vulnerability by 39%, 33%, and 28% respectively, but conversely increase their vulnerability to external water shortages i.e. indirect vulnerability. Establishing megacity physical and virtual water resource networks based on input-output analysis provides an opportunity for urban water planners to internalize the risk of their external water footprint. Avoiding import water-intensive products from regions suffering extreme water stress, or managing indirect vulnerability through cooperation with those regions are suggested as viable water management approaches.

Biofiltration systems are one type of vegetated sustainable drainage systems particularly suited for diffuse pollution control and with a relatively compact footprint that make them an ideal choice for retrofit in urban areas. Existing knowledge on dissolved pollutant fate in biofilters, the influence of their design and configuration on hydrological, pollutant removal and long term performance is limited. This paper focuses on investigating the influence of amended media on the removal performance of dissolved pollutants through a laboratory study using batch test and mesocosms under controlled condition. Duplicate control and three amended configurations comprising of Zeolite, Granular Activated Carbon, and a mix of both, were dosed with synthetic stormwater runoff simulating typical pollutants concentration of urban runoff areas. In this paper the results for phosphate removal are reported. Preliminary results suggested that there is significant difference between inlet and outlet phosphate concentration (P < 0.001) with the configurations with both the amendments and the zeolite resulting in highest average removal performance. Mean phosphate removal performance for the four configurations were lower than 27%. Batch test highlighted the occurrence of leaching from topsoil and woodchips used in the biofilters. Higher phosphate removal was observed after longer dry periods between runs.

Lake Taihu was chosen as a case for parameter uncertainty and sensitivity analysis of water quality simulation in large shallow lakes. Forty parameters in Environmental Fluid Dynamic Code model (EFDC) were filtered and analyzed. The results showed that parameters had a considerable influence on simulation and three groups of parameters related to algal kinetics (i.e. PMc, BMRc and PRRc), light (KeChl) and temperature (KTG1c) were very sensitive. For shallow lakes with frequent algal blooms, light extinction due to Chlorophyll-a is also a sensitive parameter. While the temperature effect coefficient for algal growth is sensitive for lakes with seasonal temperature variation. Sensitive parameters and their relevant uncertainty varied spatially. For high nutrients and algae concentration subareas, temperature was more likely to be a limiting factor, whereas sensitive factors could be light in lower concentration subareas. Since most sensitive parameters were related to algae, uncertainty in simulation increased with increasing algal kinetic processes over time and varied in different subareas. Lower nutrients and algae concentration subareas were more easily influenced by model parameters while nearshore areas were highly influenced by boundary conditions. For better simulation of water quality, variable stoichiometry phytoplankton models should be considered and zooplankton need to be integrated into the model explicitly rather than a fixed predation rate.

Summary 1.The flow regime of a river is fundamental in determining its ecological characteristics. Impoundment of rivers has been documented to severely impact the natural flow regime, resulting in abiotic and biotic changes in downstream ecosystems. Contemporary water legislation is driving increasing concern among environmentalists and water resource managers with respect to how these impacts can be mitigated. This has stimulated research aimed at assessing the relationship between reservoir outflow modification (i.e. managed environmental flows) and downstream ecosystem responses. 2.We carried out a critical review and synthesis of the global literature concerning post-impoundment reservoir outflow modification and associated downstream biotic and abiotic responses. Seventy-six studies published between 1981 and 2012 were analysed. In contrast to previous studies of this subject, we systematically assessed the methodological quality of research to identify strengths and weaknesses of the approaches. We also undertook a novel quantification of ecosystem responses to flow modification, thus enabling identification of priorities for future research. 3.We identified that: (i) there was a research bias towards North American and Western European studies; (ii) the majority of studies reported changes in flow magnitude (e.g. artificial floods) and primarily focused on traditionally monitored ecological groups (e.g. fish); (iii) relationships between flow, biota (e.g. macroinvertebrates) and water quality (e.g. electrical conductivity and suspended solids concentration) were evident, demonstrating the potential for managed environmental flows to manipulate river ecosystems; (iv) site-specific factors (e.g. location, climate) are likely to be important as some ecosystem responses were inconsistent between studies (e.g. fish movement in response to increases in flow magnitude); and (v) quality of study design, methodological and analytical techniques varied, and these factors may have contributed to the reported variability of ecosystem response. 4.To advance scientific understanding and guide future management of regulated flow regimes, we highlight a pressing need for: (i) diversification of study locations as well as flow modification and ecosystem response types assessed; (ii) a focus on understanding flow–ecosystem response relationships at regional scales; (iii) further quantitative studies to enable robust statistical analyses in future meta-analyses; and (iv) robust monitoring of flow experiments and the use of contemporary statistical techniques to extract maximum knowledge from ecological response data.

Research on blue and green water footprints (WF) for China has typically been carried out based on bottom-up and top-down approach using a single-region input&ndash, output table. However, this research typically lacks detail on the sectoral interrelationships which exist between China and its trading partners in other countries/regions of the world. Here, a multi-region input&ndash, output approach using the WIOD database was applied to quantify the blue and green WF for China in 2009. The quantification was conducted from both production (WFP) and consumption (WFC) perspectives. The results show that the total WFP for China in 2009 was 1152.2 km3, second only to India. At 1070.9 km3, China had the largest WFC volume in the world. The internal WF was 953.5 km3, taking the substantial share for both the WFC and WFP. Overall, China&rsquo, s trade resulted in a net export of 53.5 km3 virtual water. In contrast, the agricultural sector resulted in a net import of 70.6 km3 virtual water to China, with United States, Brazil, and Canada acting as major suppliers. This study suggests that quantifying the WF of China at global level through a MRIO framework is a necessary step towards achieving sustainability for China&rsquo, s water management.

Trade of commodities can lead to virtual water flows between trading partners. When commodities flow from regions of high water productivity to regions of low water productivity, the trade has the potential to generate water saving. However, this accounting of water saving does not account for the water scarcity status in different regions. It could be that the water saving generated from this trade occurs at the expense of the intensified water scarcity in the exporting region, and exerts limited effect on water stress alleviation in importing regions. In this paper, we propose an approach to measure the scarce water saving associated with virtual water trade (measuring in water withdrawal/use). The scarce water is quantified by multiplying the water use in production with the water stress index (WSI). We assessed the scarce water saving/loss through interprovincial trade within China using a multi-region input-output table from 2010. The results show that interprovincial trade resulted in 14.2 km3 of water loss without considering water stress, but only 0.4 km3 scarce water loss using the scarce water concept. Among the 435 total connections of virtual water flows, 254 connections contributed to 20.2 km3 of scarce water saving. Most of these connections are virtual water flows from provinces with lower WSI to that with higher WSI. Conversely, 175 connections contributed to 20.6 km3 of scarce water loss. The virtual water flow connections between Xinjiang and other provinces stood out as the biggest contributors, accounting for 66% of total scarce water loss. The results show the importance of assessing water savings generated from trade with consideration of both water scarcity status and water productivity across regions. Identifying key connections of scarce water saving is useful in guiding interregional economic restructuring towards water stress alleviation, a major goal of China's sustainable development strategy.

Residuum lodges comprise small dams constructed on feeder streams immediately before they enter a reservoir, behind which ponds form, where sediment is deposited. Despite their construction on many impoundment reservoirs (IRE) and catchwaters, little research has previously investigated their efficacy at removing sediments from feeder streams. The current pilot study has, therefore, been carried out at an IRE supplying Halifax, West Yorkshire, UK, where a residuum lodge was recently cleaned out. Sediment concentrations reaching the reservoir were reduced by up to 42% although no certain impacts were noted on the other water quality variables that were measured. Moreover, it was found that the clearance operation did not result in the release of excessive quantities of sediment into the reservoir. It was estimated that the cleared residuum lodge would take 12 years to refill. A survey of other residuum lodges in the Yorkshire region showed there to be considerable differences in their remaining capacities.

Flexible-membrane plate-and-frame filter presses are used by many industries to dewater compressible slurries. The dewaterability of such materials is described well by compressional rheology theory. The one-dimensional numerical model of fixed-cavity plate-and-frame filtration described recently (Stickland et al. Chem Eng Sci. 2006;61:3818–3829) is extended here to include the squeeze phase employed by flexible-membrane filter presses. The model is validated by comparing full-scale plant data from an industrial waste slurry with model predictions based on the fundamental material properties of the feed slurries (measured using laboratory-based filtration tests), the operating conditions and the press dimensions. The model is then used to investigate the optimization of the throughput and final cake solids for flexible-membrane filter presses. By providing an accurate model based upon the material properties under the filtration environment seen by the material, the need for pilot-scale tests is eliminated. © 2007 American Institute of Chemical Engineers AIChE J, 2008

A model of fixed-cavity plate-and-frame filter presses is developed based on the theoretical framework developed by Buscall and White (1987. The consolidation of concentrated suspensions. Part 1. The theory of sedimentation. Journal of the Chemical Society. Faraday Transactions. I, Physical Chemistry in Condensed Phases 83, 873–891) and the piston-driven filtration model of Landman et al. (1991. Dewatering of flocculated suspensions by pressure filtration. Physics of Fluids. A, Fluid Dynamics 3(6), 1495–1509). The model properly accounts for compression of the suspension network structure within a filter cake in one dimension over a fixed cavity and allows for the effect of membrane resistance and ramping pressures. The model is validated by comparing on-site measurements of actual process performance at two water treatment plants with model predictions based on fundamental material properties of the feed slurries, the operating conditions and the press dimensions. The material properties are measured using laboratory based filtration tests. The model is then used to investigate the optimisation of press throughput and cake solids for a ferric water treatment slurry.

Capillary suction time (CST) and specific resistance to filtration (SRF) measurements are commonly used in the characterisation of sludges and for the prediction of efficient operation of dewatering processes such as centrifugation and filtration. Whilst occasionally useful in predicting trends, they do not assist in the design and optimisation of dewatering devices from first principles. Recent work in our laboratories has led to the development of a technique for the fast measurement of the permeability and compressibility of sludge. The use of a single volume-fraction dependent parameter, namely the solids diffusivity, D (ϕ), calculated from permeability and compressibility, enables full characterisation of the dewaterability of sludge. This allows different sludges to be compared in an unequivocal fashion. Data is presented for a range of sludges from different sources showing vastly different dewatering properties. The dewaterability of the different sludges is easily compared and the true role of flocculants in dewatering is highlighted.

In the presence of excess LiNiPr2, lanthanide tris(di-isopropylamides) Ln(NiPr2)3 form bimetallic complexes [Li(THF)Ln(NiPr2)4], which are common impurities in the synthesis of [Ln(NiPr2)3(THF)]. NMR studies show that at room temperature [Li(THF)Ln(NiPr2)4] consists of a tetrahedral array of four equivalent NiPr2 ligands on Ln, with the Li(THF) moiety migrating rapidly between them. At 223 K, a bimetallic structure [(THF)Li(μ-NiPr2)2Ln(NiPr2)2] is frozen out. [Ln(NiPr2)3(THF)] may be synthesized free of [Li(THF)Ln(NiPr2)4] impurity by reaction of LnCl3 with 2.5 equivalents of LiNiPr2.

Photoelectrocatalysis driven by visible light offers a new and potentially powerful technology for the remediation of water contaminated by organo-xenobiotics. In this study, the performance of a visible light-driven photoelectrocatalytic (PEC) batch reactor, applying a tungsten trioxide (WO3) photoelectrode, to degrade the model pollutant 2,4-dichlorophenol (2,4-DCP) was monitored both by toxicological assessment (biosensing) and chemical analysis. The bacterial biosensor used to assess the presence of toxicity of the parent molecule and its breakdown products was a multicopy plasmid lux-marked E. coli HB101 pUCD607. The bacterial biosensor traced the removal of 2,4-DCP, and in some case, its toxicity response suggests the identification of transient toxic intermediates. The loss of the parent molecule, 2,4-DCP determined by HPLC, corresponded to the recorded photocurrents. Photoelectrocatalysis offers considerable potential for the remediation of chlorinated hydrocarbons, and that the biosensor based toxicity results identified likely compatibility of this technology with conventional, biological wastewater treatment.

Lithium bis(o-anisyl)phosphide (1)may be prepared by reaction of n-BuLi with bis(o-anisyl)phosphine in THF or toluene; sodium bis(o-anisyl)phosphide (2) is prepared by reaction of sodium with tris(o-anisyl)phosphine in liquid ammonia/THF; both compounds are isolated as unsolvated solids. 1 decomposes quantitatively in THF to give tetrakis(o-anisyl)diphosphine (4); 2 decomposes in THF to give a mixture containing 4 and bis(o-anisyl)phosphine. Addition of diglyme to 2 gives [Na{mgr;-P(C(6)H(4)OMe-o)(2)}(MeO(CH(2)CH(2)O)(2)Me)](2) (2a), which has been characterized by single-crystal X-ray diffraction. Each Na atom in 2a is 6-coordinate, being bonded to two P atoms, three diglyme O atoms, and one O atom from an o-anisyl group. Crystal data: monoclinic, P2(1)/n, a = 14.549(4) Å, b = 18.555(6) Å, c = 15.846(4) Å, beta = 91.07(2) degrees, Z = 4, final R = 0.041, R(w) = 0.053.

Azatrane complexes with the [N(CH2CH2NSiMe3)]3- ligand are known for main group, transition, and actinide metals but, until now, not for the rare earths. Here we report the reaction of Li3[N(CH2CH2NSiMe3)3] with YCl3 to give a remarkable Y2Li3 cluster containing not only a [N(CH2CH2NSiMe3)3]3- ligand but also fragments arising from a facile cleavage of THF solvent.