Saltwater intrusion is compromising the reuse of treated water from the Vila Real de Santo António Wastewater Treatment Plant (WWTP), one of the measures to tackle the drought in the Algarve, an official source told Lusa.
The Algarve is on alert due to the drought and water efficiency plans include the use of Water for Reuse (WFR) from the Vila Real de Santo António wastewater treatment plant to water two golf courses in Castro Marim, but the salinity of the wastewater coming from the networks of the two municipalities is hindering this objective, acknowledged a source from Águas do Algarve.
According to the same source, diagnostic work is being carried out by the entities managing the supply networks of both municipalities in the Faro district and the results obtained have already revealed that “in some situations, there is salt water entering the drainage systems of the low network”, both in Castro Marim and Vila Real de Santo António.
“Given the concentration of salinity in the wastewater and, consequently, in the treated effluent and in the ApR (it should be noted that salinity is not removed at the WWTP), it is only possible for the Castro Marim golf courses to reuse around 30% of what was planned,” Águas do Algarve quantified.
The company explained that, in total, the two golf courses in Castro Marim were expected to be able to reuse at least 0.6 cubic hectometers (hm3) per year, which could rise to around 0.87 hm3 per year under extreme conditions.
The managing bodies of the low-level networks of the two municipalities in the eastern Algarve, Castro Marim council and Águas de Vila Real de Santo António, are carrying out work using technology and video cameras to identify points in the network where there is salt intrusion and to “outline interventions to correct” the problems detected.
“This situation is particularly relevant for the Vila Real de Santo António wastewater treatment plant, since the presence of high salinity in the effluent and, consequently, in the ApR, severely limits its use for irrigation, in this case of the two golf courses in Castro Marim,” explained the company responsible for supplying high-level water to the 16 municipalities in the Algarve.
Regarding the works and interventions needed to prevent salt water from reaching the wastewater treatment plant and the deadlines for their completion, the company said that “only after the diagnostics have been carried out, which are expected to be completed in the first half” of this year, will the data be known that will allow the interventions and the respective budgets to be defined”.
“Solving this problem is primarily the responsibility of the entities that manage the downstream networks, but Águas do Algarve is making itself available in various ways to support and participate in this process,” he added, acknowledging that the problem of saline intrusion into the drainage networks occurs in other areas of the Algarve, such as Tavira, Olhão, Faro, Portimão and Lagos.
Lusa questioned the entities that manage the water supply in the two municipalities located on the banks of the River Guadiana, but only Castro Marim replied, through the deputy mayor, Filomena Sintra, who said that “a number of points have already been identified, with different pathologies, and with interventions that will also have to be different”.
“What’s next is to draw up specifications for an intervention to create the necessary watertightness,” he said, adding that Águas do Algarve will collaborate in terms of public procurement procedures and drawing up the specifications.
Asked about the investment needed, Filomena Sintra replied that “at the outset, there are 500,000 euros earmarked” for Castro Marim to intervene in this area, under the mechanisms of the Council of Ministers’ resolution that declared a drought alert in the Algarve, but it will be necessary to wait for the diagnostic work to be completed to find out if they are sufficient.
