Performance of enviss? stormwater filters: results of a laboratory trial

An experimental study was undertaken by Monash University to develop and test enviss? stormwater treatment and harvesting technologies - non-vegetated filtration systems with an extremely low footprint. This paper focuses on the water quality and hydraulic performance of two systems tested over a 'year' of operation in a Melbourne climate: (1) REUSE enviss? filters, designed for stormwater harvesting systems for non-potable supply substitution, and (2) WSUD enviss? filters, developed to treat urban stormwater prior to discharge to downstream systems. The presence of chlorine as a disinfection agent proved to be very efficient for the removal of microorganisms in REUSE enviss? filters. WSUD enviss? filters had the benefit of providing an elevated nutrient treatment performance, due to an extended depth of filter media. However, nutrient outflow concentrations (total nitrogen (TN) in particular) were found to increase during the testing period. Also, extended dry weather periods were found to have a detrimental effect on the treatment performance of almost all pollutants for both filters (nutrients, Escherichia coli and heavy metals). Although hydraulic conductivity results indicated two or three sediment trap replacements per year are required to maintain filtration rates, it is expected that the compressed loading rate schedule overestimated this maintenance frequency.     

Tragedy? What tragedy? Swords of Damocles and common property irrigation

Discourse on common pool resources that are governed by common property regimes is commonly characterized by ‘tragedy’ and ‘threats’ to ‘community’ cooperation. This article questions the relevance of these notions in relation to changing rural reality in the hills of Nepal. Farmers individualize water tenure to overcome the shortcomings of common property regime irrigation for diversified crops. While cooperation in irrigation may decrease, new types of cooperation emerge that reflect a wider range of institutions suited to diversified and complex livelihood portfolios.     

Evaluation of the origin of nitrate influencing the Klju? groundwater source, Serbia

This paper describes the use of the dual isotope method involving δ(15)N and δ(18)O measurements of dissolved nitrates to assess the origin and fate of groundwater nitrate at the Klju? groundwater source, Serbia. A sampling campaign was conducted in September 2007 during flow conditions obtaining groundwater from observation wells and river water fed by a shallow aquifer hosted in alluvial (sandy-gravel) sediments. Nitrate isotope ratios ranged from +5.3 to +16.9‰ and δ(18)O(NO(3)) values varied from -2.3 to +5.0‰. Two major contamination sources were identified with isotopic compositions characteristic for nitrate derived from nitrification of soil organic nitrogen (+5.3 to +7.8‰ for δ(15)N) resulting in nitrate concentrations of 33.6 and 78.8 mg/L and nitrate derived from animal wastes or human sewage, e.g. via septic systems, yielding δ(15)N values of +9.9 to +11.9‰ and elevated nitrate concentrations of 31.2-245.8 mg/L. The occurrence of nitrification and denitrification was also revealed based on concentration and isotope data for dissolved nitrate.     

Does the weight of riparian trees destabilize riverbanks?

In contrast to the generally accepted stabilizing effects of riparian vegetation, the surcharge of trees on riverbanks has been widely implicated as a source of bank instability. Fieldwork conducted along the Latrobe River in Victoria, Australia shows that the bank‐destabilizing effects of surcharge, due to silver wattle (Acacia dealbata), are minimal. Field observations indicate that it is unlikely that the weight of silver wattles growing on an otherwise stable bank section will directly cause mass failure. Observations of deep‐seated failures and silver wattle stands on the Latrobe River indicate that where average‐sized slump‐blocks support an average number of average‐sized silver wattles, the trees represent only 4.1% of the total saturated slump mass. Infinite slope stability analysis indicates a threshold of around 48° where banks become prone to shallow‐planar slide failures as they steepen. Where bank sections are inherently unstable and prone to shallow‐planar slide failure, the additional weight of the trees may contribute to overall instability. However, manipulation of other stability parameters within reasonable constraints negates the effect of surcharge so it is not possible to demonstrate conclusively a destabilizing influence of silver wattles. Copyright © 2000 John Wiley & Sons, Ltd.     

Potentials and limits of anaerobic digestion of sewage sludge: energy self-sufficient municipal wastewater treatment plant?

Anaerobic digestion is the only energy-positive technology widely used in wastewater treatment. Full-scale data prove that the anaerobic digestion of sewage sludge can produce biogas that covers a substantial amount of the energy consumption of a wastewater treatment plant (WWTP). In this paper, we discuss possibilities for improving the digestion efficiency and biogas production from sewage sludge. Typical specific energy consumptions of municipal WWTPs per population equivalent are compared with the potential specific production of biogas to find the required/optimal digestion efficiency. Examples of technological measures to achieve such efficiency are presented. Our findings show that even a municipal WWTP with secondary biological treatment located in a moderate climate can come close to energy self-sufficiency. However, they also show that such self-sufficiency is dependent on: (i) the strict optimization of the total energy consumption of the plant, and (ii) an increase in the specific biogas production from sewage sludge to values around 600 L per kg of supplied volatile solids.     

SBR treatment of olive mill wastewaters: dilution or pre-treatment?

The olive-oil extraction industry is an economically important activity for many countries of the Mediterranean Sea area, with Spain, Greece and Italy being the major producers. This activity, however, may represent a serious environmental problem due to the discharge of highly polluted effluents, usually referred to as 'olive mill wastewaters' (OMWs). They are characterized by high values of chemical oxygen demand (COD) (80-300 g/L), lipids, total polyphenols (TPP), tannins and other substances difficult to degrade. An adequate treatment before discharging is therefore required to reduce the pollutant load. The aim of the present paper was to evaluate performances of a biological process in a sequencing batch reactor (SBR) fed with pre-treated OMWs. Pre-treatment consisted of a combined acid cracking (AC) and granular activated carbon (GAC) adsorption process. The efficiency of the system was compared with that of an identical SBR fed with the raw wastewater only diluted. Combined AC and GAC adsorption was chosen to be used prior to the following biological process due to its capability of providing high removal efficiencies of COD and TPP and also appreciable improvement of biodegradability. Comparing results obtained with different influents showed that best performances of the SBR were obtained by feeding it with raw diluted OMWs (dOMWs) and at the lowest dilution ratio (1:25): in this case, the removal efficiencies were 90 and 76%, as average, for COD and TPP, respectively. Feeding the SBR with either the pre-treated or the raw dOMWs at 1:50 gave very similar values of COD reduction (74%); however, an improvement of the TPP removal was observed in the former case.     

How participatory can participatory modeling be? Degrees of influence of stakeholder and expert perspectives in six dimensions of participatory modeling.

The authors are involved in a project aiming at the development of a methodology for participatory modeling as a tool for public participation in water resource management. In this paper, some examples of different degrees of stakeholder influence in six key dimensions of participatory modeling are identified and discussed. Arnstein's (A ladder of citizen participation. Journal of the American Institute of Planners, 1969, 4, 216-224) critical discussion of different degrees of "real" decision-making power is taken as a point of departure to assess possible degrees of stakeholder influence. Can we as participatory modelers be sure that we are really inviting our research objects to an equal communicative relationship where local perspectives, knowledge and priorities are respected to the same extent as central and/or expert perspectives? This paper presents an approach that could be used as a tool for structured reflection to avoid unreflective tendencies towards expert knowledge dominance and low degree of stakeholders' real influence over the process.     

Exporting water from the desert? An analysis of the virtual water content of Saudi Arabian agricultural exports

This study applies input-output analysis to evaluate and trace Saudi Arabia’s virtual water exports arising from exports of agricultural products. Saudi Arabia’s total virtual exports in 2011 were around 2.42 km³, mainly to neighbouring Arab countries. This amount is enough to meet the water demand of the country’s entire population. Agricultural exports seem economically beneficial only because they rely on groundwater; however, since the indirect cost of desalinating equivalent amounts of water for domestic purposes is much higher, a better strategy would have been to direct those water resources towards domestic needs.     

Water security in Himalayan Asia: first stirrings of regional cooperation?

The challenges of freshwater cooperation and the links between the global policy agenda and national water management are more obvious and easier to spell out at a regional level than in the global arena. By analysing how the existing regional regime within Himalayan Asia contributes to the development of international water law, this paper identifies gaps in our current understanding of regional approaches in international law and outlines pathways for addressing them.     

Lost in transition? The introduction of water users associations in Uzbekistan

A “policy as process” perspective is adopted to analyze the early period of water users associations (WUAs) in Uzbekistan (2000–2006). The article is based on extensive fieldwork (in 2005–2006) and analysis of policy and other relevant documents. It is shown that WUAs have a role and logic beyond water management and are used by the state as instruments with which to monitor and regulate “state-ordered” agricultural production. Through a state-centric policy process with room for local experimentation, the WUA was fit into the socio-political landscape of continued state control and the increased role of individualized risks and benefits.     

Use of a stable carbon isotope to assess the efficiency of a drinking water treatment method with CO?

CO? gas with a special isotopic signature (δ13C = -35.2‰ vs. VPDB) was used as a marker to evaluate the efficiency of a drinking water treatment method and the effect of an ultrasonic (US) stirrer. This treatment was developed to prevent precipitation and corrosion effects in water-supply systems. The research work was performed using a laboratory-scale pilot plant that was filled with tap water. The stable isotope analyses of δ13C-DIC (Dissolved Inorganic Carbon) in the water samples indicated that the maximum content of added CO? gas in DIC was in the range of 35 to 45%. The use of the US stirrer during the entire experiment decreased the method's overall efficiency by 10%, due to degassing at a late stage of the experiment but accelerated the dissolution process in the early experimental stage.     

Spatial and temporal variation in distribution of larval lake whitefish in eastern Lake Ontario: Signs of recovery?

The lake whitefish (Coregonus clupeaformis) is one of the native Lake Ontario fishes that declined severely over the past century. Recent evidence of larval lake whitefish production in a historic spawning area (Chaumont Bay) might signal a recovery of this species in New York waters. We surveyed coastal and open water areas to evaluate densities and estimate total abundance of larval lake whitefish in Chaumont Bay. Other historic spawning areas and embayments with appropriate spawning and nursery habitat were also surveyed, but only a few larvae were found outside of Chaumont Bay. Lake whitefish larvae were found in every embayment sampled within Chaumont Bay, with larval densities of nearly 600/1000 m² in some samples. Greatest abundances occurred in the northern sectors and near the mouth of the bay. Open water densities were generally less than half that of nearshore sites. The total bay-wide estimate for 2005 was approximately 644,000 lake whitefish larvae, but dropped to 230,000–400,000 in 2006 and 2007, respectively. Mean larval growth rates (0.36 mm/day) did not differ by year, but were consistently higher in early May than in late April. Lake whitefish production in Chaumont Bay is encouraging for this species, but the cause and persistence of the decline after 2005 can be determined only by continued monitoring. Other possible bottlenecks of survival may exist at juvenile and adult stages and could significantly affect recruitment dynamics. This species is sensitive to normal climatic fluctuations and increased variability associated with global climatic change could make winter nursery conditions unfavorable for this species.     

Patterns of long-term dynamics of aquatic communities and water quality parameters in the Great Lakes: Are they synchronized?

Long time series data can provide insights into dynamics of large lakes. We use the USEPA-GLNPO biological monitoring dataset (phytoplankton, benthos, zooplankton and water quality), collected from 1996 through 2016, to identify whether there is evidence of concordant linear or non-linear trends in community composition, density/biomass/biovolume and major environmental parameters. We show changes in biotic assemblages and water quality variables, particularly in Lakes Michigan and Huron. These include changes in phytoplankton biovolume and zooplankton biomass, increasing invasive Dreissena abundance and decreasing densities of other benthos. Biotic changes are accompanied by pronounced changes in water quality and nutrient ratios. Species change-points, identified using threshold indicator taxon analysis, are often less abrupt, but there are clear shifts in a large proportion of species in each assemblage. The concordance of breakpoints among assemblages or lack thereof provides valuable insight into potential drivers of ecosystem change.     

Has water-saving irrigation recovered groundwater in the Hebei Province plains of China?

This study performed a quantitative evaluation of the impact of water-saving irrigation on the groundwater regime in the Hebei Province plains area. In this work, the change in groundwater regime and the contributions of precipitation and water-saving irrigation development were investigated. The results indicate that the groundwater overdraft has been mitigated to some extent, mainly due to changes in precipitation and the implementation of water-saving irrigation, with contributions of 64.3% and 35.7%, respectively, when considering only these two factors. Water-saving irrigation is accepted as an important means for reducing groundwater depletion, but should be used in conjunction with other measures.     

Can the Regeneration of Vegetation from Riparian Seed Banks Support Biogeomorphic Succession and the Geomorphic Recovery of Degraded River Channels?

For rivers degraded by erosion and channel widening, the re‐establishment of riparian vegetation is essential. We assess the potential for riparian seed banks to facilitate natural channel contraction through the regeneration of plants involved in the biogeomorphic succession of three discrete geomorphic units of increasing age and height above the channel bed: bars, benches and floodplain. Standing vegetation upon each unit type was surveyed for four river reaches in the Hunter catchment of eastern Australia. Seed bank composition was determined using seedling emergence techniques on sediment sampled from the units. We compared species richness and composition, and longevity, growth form and seed dispersal mechanisms between the standing vegetation and seed bank species. The seed bank was similar across bars, benches and floodplain, containing mostly perennial pioneer herbs, sedges and rushes, dispersed by wind and hydrochory (water transport). While bar vegetation was similar to the seed bank, bench and floodplain vegetation included later successional species such as shrubs and trees, significantly more grasses and vines (benches: χ²_{5, N = 402} = 102.033, p < 0.001; floodplain: χ²_{5, N = 792} = 30.324, p < 0.001) and higher proportions of unassisted and animal‐dispersed seeds (benches: χ²_{5, N = 352} = 89.409, p < 0.001; floodplain: χ²_{5, N = 338} = 56.026, p < 0.001). The results suggest that seed banks may support early stages of biogeomorphic succession, via regeneration of pioneer plants. However, plants, such as shrubs and trees that are observed upon units of increasing age and height above the channel bed (i.e. benches and floodplain), are likely sourced from transient seeds produced by local vegetation, rather than seed banks. Copyright © 2014 John Wiley & Sons, Ltd.     

Progress beyond policy making? Assessing the performance of Dutch-German cross-border cooperation in Deltarhine

ABSTRACT

This longitudinal study assesses the performance of the Dutch-German cross-border water regime using a combination of performance indicators. The regime has, despite many efforts over five decades, rarely progressed beyond policy making and hardly contributed to actual problem-solving for issues such as water pollution or river restoration. Stakeholder satisfaction is nevertheless high, showing that combined performance indicators are needed to assess cross-border cooperation, and performance cannot simply be equated with problem-solving and goal attainment. Practical policy advice is provided to progress beyond policy making, focusing on policy design, network management and the adequacy of resources (financial, human, legal) for policy implementation.     

A holistic water balance of Austria - how does the quantitative proportion of urban water requirements relate to other users?

Traditional water use statistics only include the blue water withdrawal/consumption of municipalities, industry and irrigated agriculture. When, however, green water use of the agricultural sector is included as well as the virtual water use/water footprint (WF), water use quantity statistics become very different. In common water use statistics, Austria withdraws in total about 2.5 km(3) per year, only 3% of available resources (total discharge 81.4 km(3) = surface and ground water). The total water consumption (0.5 km(3)) is less than 1% of available resources. Urban (municipal) water requirements account for 27% of total withdrawal or 33% of consumption. When agricultural green water use (cropland) is included in statistics, the fraction of municipal water requirements diminishes to 7.6% of total withdrawal and 2.5% of total consumption. If the evapotranspiration of grassland and alpine meadows is also included in agricultural green water use, this fraction decreases to 3.2% and 0.9% respectively. When the WF is assessed as base value for water use in Austria, the municipal water use represents 5.8% of this value. In this globalized world, these traditional water use statistics are no longer recommendable. Only a holistic water balance approach really represents water use statistics.     

What Is the Potential of Integrating Phase Space Reconstruction with SVM-FFA Data-Intelligence Model? Application of Rainfall Forecasting over Regional Scale

Rainfall modeling is one of the major component process in the meteorological engineering. Hence, exploring an advance and reliable intelligent model for its forecasting is essential for water resources engineering. In this current research, novel integrative intelligence model coupled with phase space reconstruction is proposed to forecast monthly rainfall in Chhattisgarh State, India. The proposed model is a hybridization of support vector machine (SVM) model with firefly optimization algorithm (FFA). The modeling is undertaken based on three stages starting with configuring the delay time and embedding dimension using mutual information and false nearest neighbors to determine the input matrix of the forecasting model. In the second stage, the firefly optimizer is employed to tune the SVM model. Finally, the hybrid model is conducted to forecast the monthly time scale rainfall time series. Monthly time scale rainfall data for sixteen raingauge stations over a century (1901–2002) are utilized and tested. A validation of the capacity of the suggested model is carried out by comparing the accuracy results with classical SVM and hybrid SVM-FFA “without mutual information analysis” models. The three predictive models are trained using 75% of available data set and tested the remaining 25% dataset. The model’s results were statistically verified using mean absolute error and best-good-fitness measurements in addition to Taylor diagram visualization. In conclusion, the proposed model was significantly improved the forecasting accuracy of the modeling. Also, it was exhibited a very robust intelligent model that can be applied for the Indian regional zone for monthly rainfall forecasting.     

Visible light assisted photocatalytic degradation of methyl orange using Ag/N-TiO? photocatalysts

For the sake of efficient utilization of sunlight, Ag nanoparticles loaded N-doped TiO? photocatalysts (Ag/N-TiO?) were successfully fabricated via a two-step method to make the best use of the respective advantages of noble metal loading and nonmetal doping. Ag/N-TiO? was characterized using XRD, XPS and UV-Vis DRS. Compared to TiO?, the dramatic enhancement of the visible-light-induced photocatalytic degradation ef?ciency of Ag/N-TiO? obtained for the degradation of methyl orange should be attributed to the synergistic effect of N-doping and Ag-loading, including the good visible light absorption and the effective electron-hole separations. This demonstrates Ag/N-TiO? is a promising photocatalytic material for organic pollutant degradation under visible light irradiation.