SAFE T WATER : an eco-sustainable technology to replace aluminum salts with natural coagulants.

More than 243000 Hm3/year of drinking water is used in Europe. The popularity of metallic coagulants is due to their comparatively low cost, high availability, and efficiency in removing turbidity and color and sometimes helped by flocculants as polyacrylamides, starch or PolyDadmacs. Water & wastewater treatment drives the market to reach $14.7 Billion by 2024 in this kind of reagents. In this project, a synthetic coagulant will be replaced by a single improve multifunctional organic polymer based on natural plant extracts as a three-step treatment procedure, encompassing coagulation, flocculation and neutralization of pH.

The main drawback of synthetics coagulants is the negative impact on human health and the environment. There are corrosive reagents that contribute undesirable elements such as metals , chlorides or sulphates to drinking water. The sludge generated is known as “alum sludge”, which is the most common residual from water treatment plants. They can cause a deterioration of the pipeline network and produce a waste that finally end in soils or landfills. Moreover, the sludge contains a 7-17% of aluminum concentration, which is mainly used in the agriculture and can be adsorbed, finally, by plants.  Thus, there are two ways to reduce aluminum concentration, one is the efficiency of the coagulation process and reduction of complementary reagents and the other is the substitution of this reagents by a natural one.

Natural coagulants are an alternative of aluminum or iron salts and avoid dissolved aluminum control as required by Directive (UE) 2020/2184, as well as lower costs in complementary reagents. Complementary flocculants as polyacrylamides are limited by the World Health Organization to 0.5 μg/L and are considered harmful to human health. The sludge obtained with the natural coagulant provide organic matter and adsorbs phosphorus so can be used as an active substrate and once saturated, as an agricultural substrate, thus participating in the concept of circular economy.

The main objective of Safe T Water project is to validate a new innovative and environmentally friendly technology in two drinking water treatment plants (DWTP) located in Spain. The first one it is located in Valencia, with a daily production of 48,000 m3 and 750,000 inhabitants and the second one in Madrid, with a daily production of almost 700,000 m3 and supplying 3.2 million inhabitants representing a hard and soft water qualities.

There is a first stage of natural coagulant production in a batch, focused on the start-up and continuous production and manufacturing the product necessary to feed both pilot scale treatment plants. This batch has a production of 4000  Kg/month.

The natural coagulant is evaluated in a 6 m3/h pilot plant flow rate , consisting of a homogenization tank and a coagulation-flocculation and lamellar settling stage followed by a  sand filtration. A Full-scale implementation phase including the validation of the new technology through real drinking water facility is going to reproduce the outcomes.

The comparison between both coagulants must be made under the same conditions, establishing the effectiveness of the natural one as a real and sustainable alternative and this provides to Safe T Water Project a relevant role.