Miquel Salgot

Quantification of pathogenic microorganisms and microbial indicators in three wastewater reclamation and managed aquifer recharge facilities in Europe

Managed Aquifer Recharge (MAR) is becoming an attractive option for water storage in water reuse processes as it provides an additional treatment barrier to improve recharged water quality and buffers seasonal variations of water supply and demand. To achieve a better understanding about the level of pathogenic microorganisms and their relation with microbial indicators in these systems, five waterborne pathogens and four microbial indicators were monitored over one year in three European MAR sites operated with reclaimed wastewater. Giardia and Cryptosporidium (oo)cysts were found in 63.2 and 36.7% of the samples respectively. Salmonella spp. and helminth eggs were more rarely detected (16.3% and 12.5% of the samples respectively) and Campylobacter cells were only found in 2% of samples. At the Belgian site advanced tertiary treatment technology prior to soil aquifer treatment (SAT) produced effluent of drinking water quality, with no presence of the analysed pathogens. At the Spanish and Italian sites amelioration of microbiological water quality was observed between the MAR injectant and the recovered water. In particular Giardia levels decreased from 0.24-6.14 cysts/L to 0-0.01 cysts/L and from 0.4-6.2 cysts/L to 0-0.07 cysts/L in the Spanish and Italian sites respectively. Salmonella gene copies and Giardia cysts were however found in the water for final use and/or the recovered groundwater water at the two sites. Significant positive Spearman correlations (p<0.05, r(s) range: 0.45-0.95) were obtained, in all the three sites, between Giardia cysts and the most resistant microbial markers, Clostridium spores and bacteriophages.

Impact of design and operation variables on the performance of vertical-flow constructed wetlands and intermittent sand filters treating pond effluent.

With the aim of improving the quality of the effluent from a waste stabilization pond (WSP) different types of vertical-flow constructed wetlands (VFCWs) and intermittent sand filters (ISFs) were tested at a pilot plant in Aurignac (France). The effectiveness of each design at upgrading the pond effluent was studied over a period of 2 years. Physicochemical parameters were monitored by taking composite samples over 24h and grab samples every week. The hydraulic behaviour of the filters was studied using (NaCl) tracer tests and monitoring the infiltration rate. This paper describes the influence on the performance of the beds of: (a) the characteristics of the medium (type of sand, depth, and presence of Phragmites); (b) feed modes; and (c) the presence of an algae clogging layer. The study demonstrates the viability of VFCWs and ISFs as means of upgrading effluent from WSPs. For hydraulic loads (HL) of up to 80cm/day, both technologies effectively retain algae, complete organic matter degradation, and nitrify the pond effluent. The presence of plants did not significantly affect the performance of the filters although it was important in terms of maintenance. The deeper filters presented better removals for all the parameter tested, due to higher hydraulic detention times (HDTs). The dosing regime and resting period duration all affected the hydraulic performance and purification efficiency of the filters.

Water Reuse in EU States: Necessity for Uniform Criteria to Mitigate Human and Environmental Risks

Water quality criteria are an indispensable part of water reuse projects aiming to ensure the protection of public health and the environment. In addition, criteria can affect the development, public acceptance, and economic viability of water reuse projects. Currently no uniform criteria exist, but they diverge, often greatly, between countries and states. The authors briefly present the evolution of reuse criteria worldwide and discuss emerging issues related to ecological and public health risks that have not addressed adequately in existing criteria. They specifically focus on European Union (EU) countries and present their water reuse status based on the published data and the existing (or nonexisting) reuse frameworks. Data gathered from public agencies reveal a high potential for water reuse in the EU that could potentially contribute to ensuring that fresh water is available for all sectors and to protect the environment, but it has not expanded at the expected rates. The lack of water reuse criteria was thought as the most important cause for this delay. lasting recent years, however, several countries, particularly those located in the Mediterranean basin, established water reuse criteria. Similarities and differences as well as potential benefits and drawbacks of these criteria are discussed and interpreted with these of the other world. An important conclusion is that the criteria enacted in Greece, Italy, and Spain will probably prevent the development of water reuse projects and increase the costs. Moreover, major challenges, the future views, and the necessity for establishing common regulations for water reuse at an EU level are considered.

Using 3-D structures and their virtual representation as a tool for restoring opencast mines and quarries

An important factor in the restoration studies of quarries and open-cast mines is the ability of generating final restored models of visualisation. These 3-D models are particularly useful for presenting projects, as they can greatly enhance the analysis of different alternatives. A method involving several subroutines for simulation purposes is presented in this paper. The system allows for the simulation of a variety of geological structures, both real and restored. The subroutines facilitate: (1) the automatic integration between the restoration structure and its geotechnical and morphological parameters, (2) the achievement of a uniform slope, and (3) the adjustment of the talus of the restoration structure to the relief. Graphic output in DXF and VRML formats allows for both static and dynamic optimal visualisation. Readers interested in subroutines written in Visual Basic can contact the first author: victor@geo.ub.es.

Water reclamation and intersectoral water transfer between agriculture and cities – a FAO economic wastewater study

Cost-benefit studies on replacing conventional agricultural water resources with reclaimed water in favour of cities are still rare. Some results of a study under auspices of the Food and Agriculture Organisation (FAO) are presented. By means of an illustrative example at Lobregat River basin in Spain, it could be proved that reclaimed water reuse and intersectoral water transfer can result in economic and environmental benefits at the watershed level. The agricultural community faces cost savings in water pumping and fertilising, increases in yields and incomes; the municipality benefits from additional water resources released by farmers. Farmers should be encouraged to participate by implementing adequate economic incentives. Charging farmers with the full cost of water reclamation may discourage farmers from joining water exchange projects. Particularly in regions with water scarcity, investments in reclaimed water reuse and water exchange arrangements usually pay back and are profitable in the long term.

Evaluating the costs and benefits of water reuse and exchange projects involving cities and farmers

This article evaluates the economics of alternative water-allocation strategies involving farmers and urban water users, while also presenting a cost–benefit analysis framework for water reuse and exchange projects at the basin level. Case studies from Spain and Mexico show that such projects at the basin level can be economically efficient and financially feasible.

Management of water resources in the oasis of Figuig, Morocco

AbstractOasis and the small town of Figuig are located in the far south-east at the Oriental region of Morocco near the Algerian border. In this desert area, water resources are limited and collective sanitation is not fully applied. Water used is obtained from wells, scarce and temporary surface sources and mines (foggaras). The main irrigation technique is border irrigation, but drip systems are also being introduced. A dam is being built at some distance from the village and the possibility of reusing treated wastewater after the implementation of wastewater treatment plants (WWTPs) is being considered. Over the last years, cultivated land increased due to new wells mainly built without any control. This situation has lead to an overexploitation of the aquifer and soil salinisation. Only one neighbourhood has a complete sanitation system with sewerage and a WWTP using a series of stabilisation ponds (WSP) built in 1998 with the aim of treating the wastewater and subsequently reuse it for agricultural i...

Management of Water Resources and Wastewater Reuse in Palma de Mallorca, Balearic Islands, Spain

The Mediterranean islands are especially prone to suffer droughts because of the natural climate variability (Fontanals, 1984). The relatively scarce surface and the impossibility to catch resources from distant basins, make this environment sensible to water deficits. With a surface of 3,623 km2, the island of Majorca is one of the biggest in the Mediterranean sea. It has some 300 km of coastline and a mild climate, with sunshine quite every day. Majorca is a main tourism destination for all Europeans. Unfortunately, the island has no surface water resources, with irregular rains (Figs. 16.1 and 16.2), and a highly pervious soil, which implies the necessity to obtain resources from groundwater.

Risk Management During Effluent Application for Irrigation

Reuse of treated wastewater is a favourable direction for solving water shortage problems and meeting environmental quality criteria. Domestic wastewater in isolated communities in arid regions can be treated efficiently in a stabilization pond system. The effluent quality can be further improved when stored in a series of stabilization reservoirs. However the salinity of the wastes in the ponds will increase due to evaporation. There is a series of parameters that characterize the effluent quality for agricultural reuse. The conventional biological parameters include faecal coliforms as a microbial indicator. The use of faecal coliforms does not reflect the viral pollution of the effluent due to the poor correlation with virus occurrence. Therefore, phages are proposed as enteric virus pollution indicators. Phages exhibit similar behaviour and survival in an aquatic environment, and their quantitative assessment is easy and a reliable enteric virus measure. Field results from the treatment plant of the City of Arad (Israel) reveal the possibility of characterizing the effluent quality in stabilization ponds and additional reservoir systems. The field data also allows the type of reactor of which the system consists to be defined, and the kinetic expressions for further forecasting of the treatment system behaviour and removal rate of the pathogens.