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- Site selection for reclaimed water infiltration using GIS toolsPublication . Silva, Flora; Albuquerque, António; Marecos do Monte, Helena; Cavaleiro, Victor; Carvalho, AntónioIn the Beira Interior region (Portugal) some sources of water do not present characteristics suitable for some uses due to pollution (namely associated to the discharge of point and nonpoint effluents) or are over-exploited (namely the aquifers). However, the water demand will grow in this region to meet socio-economic activities under development (e.g. the Cova da Beira irrigation plan, irrigation of golf courses and green areas and SPAs, as well as for distribution for human and industrial consumption), which will lead to the search of alternative sources of water. The region is characterized by many disperse urban agglomerates with less than 2,000 inhabitants, where the wastewater treatment plants (WWTP) are mainly ecological systems such as constructed wetlands (CW). In this context, the treated wastewater (reclaimed water) from these ecological treatment systems should be seen as a source of water to be used and not a waste to be eliminated. After a monitoring campaign of two years at the CW system of Vila Fernando (Guarda, Portugal), the characteristics of the final effluent suggest that it could be used for aquifer recharge, not only because it is an area that uses many groundwater resources, but because other uses seem to be not relevant and would require a polishing treatment for the effluent, which would increase the costs of both investment and operation. From 6 thematic maps and environmental, technical and economic criteria, it was selected a study area of 6687 ha. This area was analysed based on the manipulation of complex information using Geographic Information Systems (GIS), which consisted on overlapping areas of exclusion and inclusion from each thematic map and the use of algebraic operations (multi-criteria analysis) to obtain a final Suitable Map that indicated an area of 6.4 ha located in anthrosols as the most favorable ones for the infiltration of reclaimed water.
- Analysis of reclaimed water application for irrigation using multi-criteria analysisPublication . Albuquerque, António; Marecos do Monte, Helena; Silva, Flora; Cavaleiro, Victor; Carvalho, AntónioApproximately 60% of the population of the Cova da Beira region (Portugal) lives in rural communities with less than 2,000 inhabitants and the wastewater treatment plants (WWTP) in the region are mainly septic tanks, constructed wetlands and trickling filters. The daily reclaimed water discharged into streams could be mainly reused for landscape irrigation of public parks and lawns and golf courses, which often means offsetting potable water for nonpotable purposes. However, those applications may require a polishing treatment to remove mainly pathogens, and trace elements. A one-year monitoring campaign was carried out in a biological aerated filter that treats the sewage of 4,000 inhabitants. The research included the measurement of the flow-rate and its characteristics in terms of pH, temperature, conductivity, BOD5, COD, TSS, TN, NH4, NO2, NO3, TP, Na, Mg, Ca, K, Cl, B, As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, total coliforms (TC), faecal coliforms (FC), E. Coli and helminths eggs (HE). Results show that the effluent concentrations of BOD5, COD, TN, TP, K, Ca and phytotoxic elements (Na, B and Cl) are compatible with the international guidelines for irrigation reuse (crop irrigation). Values of conductivity are not a risk to soil salinity, but TC, FC and E. Coli values are not compatible with the reuse guidelines and, therefore, a final disinfection must be implemented to decrease the pathogenic content. The low nitrate concentrations (<5 mg L-1) are suitable for irrigation and constitute a very low risk for groundwater contamination. GIS-based multi-criteria analysis was performed combining reclaimed water characteristics, the type and needs of the dominant crop production and environmental, technical and economic criteria. The results showed that approximately 170,000 m3 of reclaimed water annually discharged in the local stream could be reused for irrigation of 30.53 ha fruits trees, corn, olive trees and vine, located at a distance of about 1.8 km from the WWTP. The use of reclaimed wastewater in rural areas brings other advantages such as the reduction of the residual pollution load discharged in water streams and the reduction of water abstraction volumes for irrigation, which are important environmental and economics benefits, especially in periods of water shortage.