Desalination

Desalination is a process that separates most of the salts dissolved in a saline solution. There are several different techniques used to this aim, however the most extended one is Reverse Osmosis desalination. High pressure water is pumped through semi-permeable membranes that separate water and salts. The energetic efficiency in the desalination process has developed significantly in the last years rendering Reverser Osmosis the best alternative. Cadagua enjoys a well-deserved reputation as one of the first companies in the world in the field of seawater desalination through reverse osmosis. Relevant projects of the nature of Madinat Yanbu (Saudi Arabia) 50,400 m³/d, Dhekelia (Cyprus) 40,000 m³/d and Valdelentisco (Spain) 200,000 m³/d (phase I - 75,000 m³/d), consolidate Cadagua’s ranking in the international market.

Drinking Water

Drinking Water Plants turn natural or raw water into drinking water. These installations are located among the water collection installations (reservoirs and wells) and the tanks and pipes networks delivering water to households. Their mission is to eliminate the three main types of undesirable substances in the water intended for human consumption: mineral material, organic material (phenols, hydrocarbons, detergents, pesticide waste ...) and biological pollutants (bacteria, protozoos, virus, etc.) Cadagua has designed and built approximately 75 drinking water plants achieving a total treatment capacity of 4,000,0000 m³/d.

Industrial Water

Industrial effluent originates from any industrial activity that requires water, either in the production phase, transformation or handling phases, including the waste water, process water and drainage water. Depending on the process, each type of industrial activity, releases a waste water characterised by specifical type of contamination. Cadagua has more than 140 industrial waste water treatment plants in operation. The know-how obtained from this experience is applied directly to the new designs, resulting into constant optimisation of efficiency and costs. We also count with the exclusive co-operation of a major Dutch company, Paques BV, specialists in anaerobic and aerobic biological treatment.

Sewage

The term "sewage’’ comprises several types of waste water, ranging from household and services water to industrial and rain water, all collected in the municipal network. We have designed and built more than 100 sewage treatment plants reaching an installed production of 6,000,000 m³/d. With more than 35 years of experience, Cadagua is leader in the design, construction, operation and maintenance of waste water treatment plants. We are proud to count as our references the largest installations of the main cities in Spain such as Madrid, Barcelona, Bilbao, Seville etc as well as the biggest BOOT Sludge Thermal Drying installation in Europe (Sur, Madrid 300,000 Tn/year).

Sludge digestion and energy recovery

One concern modern society has is protection of the environment. Reduction in energy consumption, preservation of the sources of raw materials and the waste reduction are main factors to ensure this. Waste produced must be stabilised and made inert and, if possible, must be turned into the object of clean technology development by reuse or recycling. The stabilisation methods now used vary according to the technical and economic conditioning factors, which may be summarised as follows: aerobic or anaerobic digestion, lime treatment, composting, drying and incineration. Due to the importance of energy recovery and the possibility to obtain products that allow beneficial use of sludge from sewage, anaerobic digestion continues to be the most widespread process. The organic matter in sludge is converted biologically, under anaerobic conditions (in the absence of oxygen), into methane and carbon dioxide. That biogas produced may be used to generate power so the need for the plant to consume external power is significantly reduced. Cadagua, being aware of the environmental importance of this process, encourages research work by its R&D i team on such projects as “Gassification Process of Biosolids from sewage plants for energy use". That project was distinguished with the European Environmental Award - Basque Section and that has provided Cadagua recognition in the sector beyond our borders.

Sludge thermal drying and cogeneration

The need to seek how to finally dispose of the bio-solids generated in the sewage treatment plants has led to a process of thermal drying consisting of heat application for evaporation of a major part of the interstitial water content of these bio-solids from sewage plants. Through this process, by reducing the volume, a better final disposal of sludge generated is obtained, moreover, in many cases, it may be used as fertilizer to improve ground quality and as fuel in certain industrial processes. Cogeneration in a municipal sewage plant produces mechanical and thermal power from the digestion gas that may, in turn, be used as fuel for internal combustion engines or gas turbines. Thus, the cogeneration process fulfils two basic objectives: one economic and another environmental. This process produces electric power, reducing the operating costs and producing heat, which allows to obtain, through thermal drying, a dry granulated biosolid, with a very reduced volume, highly hygienic and with a potential subsequent use. Among its references, Cadagua counts with the largest Sludge Thermal Drying Plant in Europe (South, Madrid 300,000 tn/year) as a DBOO contract; a total of nine contracts and three of which are in Poland