Uggetti E.,University of Barcelona |
Ferrer I.,University of Barcelona |
Molist J.,Agencia Catalana de lAigua |
Garcia J.,University of Barcelona
Water Research | Year: 2011
Sludge treatment wetlands (STW) emerge as a promising sustainable technology with low energy requirements and operational costs. In this study, technical, economic and environmental aspects of STW are investigated and compared with other alternatives for sludge management in small communities (<2000 population equivalent). The performance of full-scale STW was characterised during 2 years. Sludge dewatering increased total solids (TS) concentration by 25%, while sludge biodegradation lead to volatile solids around 45% TS and DRI24h between 1.1 and 1.4 gO2/kgTS h, suggesting a partial stabilisation of biosolids. In the economic and environmental assessment, four scenarios were considered for comparison: 1) STW with direct land application of biosolids, 2) STW with compost post-treatment, 3) centrifuge with compost post-treatment and 4) sludge transport to an intensive wastewater treatment plant. According to the results, STW with direct land application is the most cost-effective scenario, which is also characterised by the lowest environmental impact. The life cycle assessment highlights that global warming is a significant impact category in all scenarios, which is attributed to fossil fuel and electricity consumption; while greenhouse gas emissions from STW are insignificant. As a conclusion, STW are the most appropriate alternative for decentralised sludge management in small communities. © 2010 Elsevier Ltd.
Flo E.,CSIC - Institute of Marine Sciences |
Garces E.,CSIC - Institute of Marine Sciences |
Manzanera M.,Agencia Catalana de lAigua |
Camp J.,CSIC - Institute of Marine Sciences
Estuarine, Coastal and Shelf Science | Year: 2011
The physicochemical and biological characteristics of coastal waters form a gradient extending from land to ocean. In the Mediterranean this gradient is particularly large, due to the sea's weak tides. Within coastal waters, those waters in contact with land are called coastal inshore waters (CIW), defined herein as between 0 and 200 m from the shoreline. Here we present the first physicochemical and biological characterization of CIW of the NW Mediterranean Sea. This case study is based on 19 years of data collected from coastal inshore (CIW; 0-200 m), nearshore (CNW; 200-1500 m), and offshore (COW; >1500 m) waters of the Catalan coast. Analyses of these data showed that the physicochemical and biological characteristics of CIW differ significantly from those of CNW and COW due to: (1) significantly higher concentrations of dissolved inorganic nutrients (nitrate = 11.07 μM, nitrite = 0.52 μM, ammonium = 6.43 μM, phosphate = 0.92 μM, silicates = 5.99 μM) and chlorophyll-a (=2.42 μg/L) in CIW than in either CNW or COW (in some cases up to one order of magnitude); (2) a greater variability of dissolved inorganic nutrients and chlorophyll-a in CIW than in CNW and COW, and (3) the presence of a mostly urban population and the effects of river inflows as a primary source of CIW variability but with minimal impact on CNW or COW. In addition, the risk of eutrophication was found to be highest in CIW, placing human and environmental interests at greater risk than in the outermost coastal waters. The results highlight the importance of considering the distinctive physicochemical and biological properties of CIW in future coastal waters studies. This is of major importance in assessments of eutrophication and coastal water quality, not only to identify the pressure-impact relationships but also to allow the timely detection of local environmental problems and thus avoid endangering the unique communities of CIW and ensuring the sustainability of human activities. In conclusion, CIW characterization is essential to integrate coastal zone management. © 2011 Elsevier Ltd.
Vera I.,University of Concepcion |
Garcia J.,University of Barcelona |
Saez K.,University of Concepcion |
Moragas L.,Agencia Catalana de lAigua |
Vidal G.,University of Concepcion
Ecological Engineering | Year: 2011
In Catalonia (Spain), a variety of different systems have been built to naturally treat liquid residues from small communities. Some of these wastewater treatment plants (WWTPs) include constructed wetlands with horizontal subsurface flow (HSSF) as secondary treatment. The present study described and characterized the performance of 11 WWTPs with secondary HSSF constructed wetland systems after an initial operating period of 8 years. The effluent concentrations of Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Total Nitrogen (TN) and Total Phosphorous (TP) were statistically analyzed, and removal efficiencies for all WWTPs including all stages in treatment were calculated. The accumulated probability functions of those parameters were evaluated to determine the influence of two different types of polishing units on the overall performance: (a) only lagoon systems and (b) lagoon systems with HSSF. The statistical analysis indicates good performance for BOD5 and TSS. In the first case, mean concentrations below 25mg/L were found in 9 of the 11 plants analyzed and removal efficiencies between 78 and 96% were observed. In the second case, mean concentrations below 35mg/L were found in 8 of the 11 plants, and removal efficiencies were between 65 and 88%. For the nutrients, the removal efficiency for TN and TP were in the range of 48-66% and 39-58%, respectively. Additionally, the analysis of the influence of the polishing units did not show a significant improvement (α>0.05) for any parameter in the wetland systems without a subsequent polishing unit. However, in the wetland systems with a polishing unit of HSSF, a significant improvement (α<0.05) was found for the effluent's BOD5, TN and TP concentrations but with no significant contribution in TSS management. © 2010 Elsevier B.V.
Ibanez C.,IRTA Aquatic Ecosystems |
Alcaraz C.,IRTA Aquatic Ecosystems |
Caiola N.,IRTA Aquatic Ecosystems |
Rovira A.,IRTA Aquatic Ecosystems |
And 6 more authors.
Science of the Total Environment | Year: 2012
The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton-dominated to a macrophyte-dominated system. This shift is well known in shallow lakes but apparently it has never been documented in rivers. Two initial hypotheses to explain the collapse of the phytoplankton were considered: a) the diminution of nutrients (bottom-up); b) the filtering effect due to the colonization of the zebra mussel (top-down). Data on water quality, hydrology and biological communities (phytoplankton, macrophytes and zebra mussel) was obtained both from existing data sets and new surveys. Results clearly indicate that the decrease in phosphorus is the main cause of a dramatic decrease in chlorophyll and large increase in water transparency, triggering the subsequent colonization of macrophytes in the river bed. A Generalized Linear Model analysis showed that the decrease in dissolved phosphorus had a relative importance 14 times higher than the increase in zebra mussel density to explain the variation of total chlorophyll. We suggest that the described changes in the lower Ebro River can be considered a novel ecosystem shift. This shift is triggering remarkable changes in the biological communities beyond the decrease of phytoplankton and the proliferation of macrophytes, such as massive colonization of Simulidae (black fly) and other changes in the benthic invertebrate communities that are currently investigated. © 2011 Elsevier B.V.
The combined use of metrics of biological quality and biomarkers to detect the effects of reclaimed water on macroinvertebrate assemblages in the lower part of a polluted Mediterranean river (Llobregat River, NE Spain)
Prat N.,University of Barcelona |
Rieradevall M.,University of Barcelona |
Barata C.,CSIC - Institute of Environmental Assessment And Water Research |
Munne A.,Agencia Catalana de lAigua
Ecological Indicators | Year: 2013
The main purpose of this paper is to evaluate whether introducing reclaimed water to the lower part of the Llobregat River has an effect on the macroinvertebrate community assemblage and the biomarker responses of the caddisfly larvae Hydropsyche exocellata. Therefore, a before-and-after experiment was carried out at two locations, upstream and downstream of the discharge effluent. At both of the stations, quantitative benthic samples were taken using a Surber net. Several biological metrics were calculated to evaluate the biological quality. For the biomarker study, the population condition of the caddisfly H. exocellata was analysed. In both sites, as a result of physicochemical water conditions, the macroinvertebrate communities are dominated by taxa that are tolerant to pollution, and the ecological status of both sites is always poor. The discharge of the reclaimed water did not affect the composition and abundance of the dominant taxa, but the few intolerant species that were found upstream before the experiment disappeared downstream. Consequently, most of the metrics indicating the level of biological impairment had slightly lower values after the introduction of the treated water, even though the ecological status was always poor. Nevertheless, significant and specific toxic effects on the collected H. exocellata larvae were observed using biomarkers. The effects included oxidative stress-related responses, such as decreased antioxidant enzyme activities and increased levels of lipid peroxidation. Therefore, indications of additional stress to the populations of the caddisfly H. exocellata were found using several biomarkers, which can indicate a potential further deterioration of the ecological status of the river. In polluted rivers, such as the Llobregat, structural indicators are unable to indicate further impairment and biomarkers may be used as an useful tool to detect then the environmental impoverishment. The combination of both kinds of indicators is necessary for the establishment of the ecological status of a system, following the indications of the Water Framework Directive (WFD). © 2012 Elsevier Ltd. All rights reserved.