During the last decade, climate change has become an important concern for Spanish citizens and has gained prominence on the public agenda. Various surveys show that most people identify it as a problem and consider it a challenge for society as a whole.
Water scarcity is one of the most visible consequences of climate change. In Spain, where most of the territory has a Mediterranean weather, droughts are a natural and recurrent phenomenon, however, its duration, periodicity and severity are constantly increasing. Moreover, the rise of water consumption for intensive agriculture and urban expansion are causing the overuse of aquifers and increasing the risk of land desertification and aridification.
This context of droughts and water scarcity requires a multilevel response, in order to alleviate the pressure over the national water system. One of the alternatives is the use of non-conventional water sources, such as desalinated and reclaimed water, considering them as a complement rather than a solution themselves.
WHAT IS RECLAIMED WATER?
In our daily life we use a fear amount of water that is later discharged into the municipal sewerage system. This wastewater is taken into the Wastewater treatment plants to undergo treatment in order to be disposed. Water reclamation allows this treated water to have a new life cycle, through the application of an additional treatment that improves water quality and enables it to be used again. This additional treatment is known as reclamation.
The Spanish Health Ministry defines reclaimed water as treated wastewater that has undergone additionally treatment, achieving the appropriate quality for their intended use.
In high density urban areas, large quantities of wastewater are produced daily, thus the reclamation treatment is a viable alternative to reduce the consumption of conventional water sources and promote a circular water management. As we shall see, the uses of this type of water are multiple and are based on compliance with strict quality standards.
WHAT ARE THE USES OF RECLAIMED WATER?
Reclaimed water has multiple potential uses, which implementation varies in from country to country, according to their specific legislation. Some of the main uses are:
- Urban uses: toilet flushing or car washing.
- Landscaped irrigation: golf courses, parks, highway medians, etc.
- Industrial: cooling purposes, plant wash down.
- Agricultural irrigation: for edible crops, pasture land or feed and fodder crops.
- Recharging of ground water.
- Augmentation of surface waters for drinking water supplies.
In Spain, reclaimed water use is regulated by the RD 1620/2007, which enables five types of uses: urban, agricultural, industrial, recreational and environmental. The decree establishes the quality criteria that reclaimed water must comply for each type of use, based on the recommendations of the World Health Organization and the criteria of the State of California, in the United States of America. This regulation defines the sampling frequency and analysis to assess water quality parameters in order to ensure public health.
The addition of reclaimed water in an integrated water resource management promotes a series of benefits for the entire circuit, such as:
- The protection of water resources;
- The reduction of coastal pollution;
- The recovery of nutrients for agriculture;
- The increase of river flows;
- The recharge of ground water;
- A sustainable water resource management.
Some of the countries and/or regions with long time experience on water reclamation are Israel, Cyprus, Australia, California and Florida in the United States of America. In Spain, the national average of water reclamation is 10 % and The Region of Murcia leads the ranking with a high 71.8 %.
RECLAIMED WATER FOR AGRICULTURE
In the European Union, water scarcity affects 17 % of its territory and 46 % of its population lives in water-stressed areas. Agriculture leads the water consumption of economic activities, with an average consumption of 36 % in the EU and a 75 % in Mediterranean countries.
Currently, the European countries are working on a common Regulation for the use of reclaimed water in agriculture. Last February, the proposal of the Regulation on minimum requirements for water reuse (COM (2018) 337) has been accepted by the European Parliament. This proposal’s objective is to lay down minimum requirements for water quality and monitoring and to set out key risk management tasks in order to guarantee that the reuse of treated waste water is safe, addresses the issue of water scarcity and contributes to the efficient functioning of the internal market.
This regulation will harmonise and regulate the use of reclaimed water in agriculture at a European level, providing sufficient flexibility for each country to adapt it to its local situation. In the case of Spain, the RD 1620/2007 is in agreement with this Proposed European Regulation, which will facilitate its implementation once it is approved. This Regulation aims to: establish the minimum requirements that reclaimed water has to comply in order to be used in agriculture; define the quality criteria for reclaimed water; require the reclamation facility operator a risk management plan; determine the procedure to acquire the permit to use reclaimed water; identify the key actors involved in the reclamation cycle and determine the validation procedure for the reclamation facility operator.
Agriculture is the main consumer of water in Spain, representing around the 75 % of the general consumption. Due to its Mediterranean climate, water scarcity increases the pressure over the water resources and thus, the necessity to diversify the water sources and the promotion of non-conventional sources such as reclaimed water. The map below shows the use of reclaimed water for agriculture in Spain.
The use of reclaimed water in agriculture brings some important benefits, such us: cutting costs associated with fresh water extraction and treatment; reduction of fertilizer use due to the nutrient content of reclaimed water (nitrogen and phosphorus); increasing the reliability of water supply by relying on urban wastewater, which volume is stable and is not directly
affected by droughts or water scarcity; lessen the exploitation of rivers and aquifers; lower the volume of treated wastewater discharged, contributing to reduce water pollution.
However, its implementation also brings a series of challenges that need to be taken into account. Those linked to economic and infrastructure issues are related with planning and investment in the area. One of them is the increase or the water cost for the farmer, due to the treatments and technology required for this water source, which may discourage its use. Secondly the investment costs to develop the infrastructure to guarantee water reclamation and its distribution to irrigation areas. Finally, the increment of energy costs derived from the treatment and distribution of reclaimed water.
A negative social perception is considered as one of the biggest difficulties for the success of a reclamation project. The main factors identified are: the disgust generated by the reclaimed water origin, health risk concerns regarding the consumption of crops irrigated with reclaimed water, distrust of the authorities managing the water sources and the preference for conventional water sources.
Therefore, to promote the use of reclaimed water in agriculture it is essential to involve the target community, since the planning phase of the project and guarantee their continuous participation during the whole process. Transparency and dialogue are fundamental to build trust between beneficiaries and all the actors involved in the management of the water source.