This news article was originally written in Spanish. It has been automatically translated for your convenience. Reasonable efforts have been made to provide an accurate translation, however, no automated translation is perfect nor is it intended to replace a human translator. The original article in Spanish can be viewed at Almería acoge la primera planta que descontamina agua con energía solar

It has a capacity of process of 21,600 tonnes of waste per year

Almería welcomes the first floor which clears water with solar energy

Drafting PU15/10/2004

The Almeria town of Níjar already has a plant collection and environmental recycling of plastic containers of pesticides through solar photocatalysis. Facility wash and triturarán the packaging of plant protection products, considered as hazardous waste, obtaining in this process, contaminated water, which will be dealt with through solar photocatalysis until its complete decontamination, allowing a subsequent reuse. Also will be shredded plastic recycled for polyethylene products.

Today the main economic activity of Almería is intensive agriculture, a sector that is growing exponentially each year. However this type of agriculture need a superior to traditional agriculture pesticides application, which leads to that when applied necessary evacuation, to be the problem with them small quantities of harmless products are also discarded.

So far these containers were burned, were abandoned or were buried, with the risk that the remains of pesticides might penetrate the soil and reach groundwater due to their high chemical stability, resistance to biodegradation and its high solubility in water.

A solution to this problem arises at the prospect of recycled plastic in these containers to other uses. But it is the problem that, following a selective collection, the containers must be washed before processing the material for re-use, resulting in a water contaminated with a mixture of different pesticides which should be treated.

As a result of this he thought in a simple and affordable technology for the treatment "in situ" of this water. Before this problem is presented as a promising application process of solar photocatalysis for degradation of pollutants, also referred to as solar detoxification, taking advantage of the energy provided by the ultraviolet radiation from the solar spectrum.

This technique provides an appropriate solution in an area of high insolation is the province of Almería. To demonstrate the feasibility of the process, was addressed in the platform Solar of Almería (PSA), in collaboration with various companies and public organizations, a study in this regard allowing a first sizing of a possible treatment plant. In 1994 was operating a pilot plant for carrying out the process.

This technology was developed by the Ciemat, together with a consortium of companies, which makes possible the practical implementation of the process of use of the solar light for the destruction of pollutants fotocatalítica organic persistent dissolved in water.

Evidence of this problem led Albaida natural resources and environment, S.A., to the processing of a project LIFE-Environment No.: LIFE00 ENV/E/000483, called: "Collection and environmental recycling of plastic containers of pesticides through solar photocatalysis"presented to the European Commission on 30/05/2001. Being the decision of the Commission on 14/08/2001, the granting of financial assistance pursuant to article 4 of Regulation (EC) No 1655 / 2000 of the Council (LIFE-Environment) for such project.

The process technology

The process of recycling of packaging waste consists of a first unit of crushed and washed industrial, which has resulted in a water with plant protection at a rally of hundreds of mg/l of TOC (Total organic carbon). Packaging is last in the plant into a hopper and from there, by means of a conveyor belt, pass to a mill grinding, working with irrigation water. The crushed (size of grinding: 2 cm) is downloaded in a hopper with water from which is elevated by a worm, which has a system of agitation to an industrial washing machine,. This computer can be controlled the time of washing, the rotational speed of the agitation system, depending on the degree of contamination of the packaging.

From here, and through another worm, the plastic is high up the centrifuge is performed where the drying of the same. Clean and dry, ready for their bagging plastic out of here.

The washing water, contaminated with residues of organic compounds that may be in packaging, passes to a storage tank. Before entering the field of solar collectors, water from washing suffers a physical-chemical treatment. The solids that might contain are removed by a filter or sieve. Later, in the conditioning tank is you added oxidants and the catalyst (FeSO₄, 7 H₂O, H₂or₂ and H₂SO₄) needed to carry out the reaction fotocatalítica.

In the tank is measured the concentration of TOC (Total organic carbon). If not achieved approximately 100 mg/l not begins the process of photocatalysis or solar detoxification, which is completed when at the exit of the collectors are 10 mg/l of COT.

The solar field is composed of several fotoreactores or solar collectors placed in series, for which the water will be circulating. Each module CPC (compound parabolic collectors) measured 1.22 m wide by 1 m long. It has 8 CPC reflectors in parallel with transparent to ultraviolet radiation tube receivers. The opening of the collector angle is 60 ° with respect to the normal. Used aluminum reflective material due to its high efficiency in the UV range and the absorber tubes uses a fluorinated polymer, it is an inert material and has an excellent stability and transmissivity UV.

Sunlight is concentrated on a glass tube that is transparent to ultraviolet light, through which circulates the water to treat. The modules are mounted on a fixed platform that allows his inclination to 37th. The modules are connected in series and the water flows directly from one to another and finally to a tank. A centrifugal pump is returning water to the collectors.

This system of solar detoxification based on the simple and efficient solar concentration with compound parabolic solar collectors, seems the best technological solution that also capture diffuse radiation. UV radiation is not absorbed by atmospheric water vapor and when there are clouds part reaches the Earth as diffuse light. This implies that the system runs on cloudy days.

Before entering the field of solar collectors, water from washing suffers a physical-chemical treatment

The solar detoxification process consists of an advanced oxidation based on the generation of some organic radicals, causing radical intermediates that end, through successive oxidative steps, in carbon dioxide, water and inorganic salts by adding oxygen. One of the possibilities that exist to generate hydroxyl radical species strongly oxidizing, is through the involvement of a semiconductor (photocatalysis), which absorbs solar radiation.

The most remarkable aspects of this process are that it allows a complete oxidation of contaminants at room temperature, the necessary oxygen for the reaction is obtained from the atmosphere, and finally, energy can be obtained from an inexhaustible source such as the Sun.

In this process fotocatalítico is going to use the photo-fentonsystem, in which ions faith^{2 +} are oxidized with H₂or₂ producing a hydroxyl radical. The Fe^{3 +} retrieved or their complexes absorb radiation producing radical free while the Fe^{2 +} is regenerated.

The reagent of Fenton (described by H. j. H. Fenton at the end of the 19th century) consists of an aqueous solution of ferrous ions and hydrogen peroxide which provides an important source of hydroxyl radicals. Under acidic conditions (pH 2-4), this reagent is a powerful oxidizer of organic compounds. On the other hand, degradation of organic compounds speeds significantly increase to complement the process with UV/visible radiation, then calling process or Photo-Fenton method. In this case, the process becomes catalytic already the Fe ion^{2 +} oxidized to Fe^{3 +} in the Fenton reaction is reduced again to Fe^{3 +} by action of the radiation, which already has a fotocatalítico process. Both reactions generate hydroxyl radical.

The use of Fe^{2 +}/Fe^{3 +} with other catalysts, such as titanium oxide, has the advantage that it is more its sensitivity to light, that grows to a length of 600 nm wavelength, which could make more use of solar energy that with other catalysts. In addition, having a homogeneous solution, the catalyst is dissolved in water, the penetration of light is higher and is controlled by the correct setting of the concentration of iron. Another advantage is that contact with contaminants is total. As disadvantage is the low required pH (< 3) to prevent the precipitation of hydroxides of iron and the need to separate the iron after the reaction.

When the water comes out of the field solar is checked in the process they have decreased considerably existing in the treatment water TOC concentrations; otherwise there would be a return of this water to the solar field, again undergo the process of solar detoxification. When one considers that the extent of COT (less than 10 mg/l of COT) at the exit of the manifold is the appropriate it is completed the process of detoxification.

The water can be recycled unless it reaches a conductivity of 10 dS/m. Once reached this value is its storage. The characteristics presented this water making it suitable for irrigation of crops in the region after mixing with water with a lower salinity.

The company

Albaida, natural resources and environment, was born in the year 1999 with the aim of providing a complete service, which includes the design, financing, construction and exploitation of infrastructures for rural development and the conservation of the natural environment.

The main objectives posed Albaida, natural resources and environment are:

Integrated water management: modernization of irrigation, sanitation, purification and reuse of waste water, supply rural villages, groundwater, municipal services for water management and remote management systems.
Waste management: solid waste, agricultural and urban, logistics of collection, clean points and transfer and treatment and recycling plants plants.
Management of the natural environment: scenic recovery, management and public use of natural spaces.
Rural development: agricultural infrastructure, farm and rural equipment.
Renewable energy production: gasification of plant waste from greenhouses and solar photovoltaics.

The development of these objectives, Albaida has a multidisciplinary team of 75 people.

The future prospects of Albaida, natural resources and environment pass through the consolidation and expansion of its activity in peninsular Southeast, as well as the study and innovation of new technologies relating to the objectives in this article.

Bibliography

J. White Gálvez; S. Malato Rodríguez. Solar photocatalysis technology. Use of solar radiation for the treatment of industrial pollutants. Monographic papers. 31. Institute for Almerian studies of the provincial Council of Almería; CIEMAT. 1996.
J. White Gálvez; S. Malato Rodríguez; P. Fernández Ibáñez; J. Cácerez Vázquez; A. Campos Rodriguez; A. Carrión Muñox. Optimization of mineralization fotocatalítica of pesticides in a solar plant by addition of inorganic oxidizing species: application to the recycling of packaging of pesticides. Ciemat technical reports. February 2000.
Treatment of waste water, waste and rubble in rural areas. Technical series. Tragsatec; School officer of agronomists of Centre and the Canary Islands. Agricultural Publisher Española, S.A. 1993.
Agricultural in the poniente almeriense residues. Mediterranean environmental group. Almería G.E.M. 1999.