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Biological Plants vs Chemical Plants

Biological Plants vs Chemical Plants

By Alfredo Seguel

Biological plants versus chemical plants: In various countries they recognize and value the ecological and highly efficient decontamination systems that Chile has been producing to treat wastewater, but the Araucanía Region would be mortgaging its future with dangerous and failed plants.

Biological Plants vs Chemical Plants in the treatment of sewage from the IX Region

Sewage plants: Chile, a great exporter to the world of biofilters (earthworms); and the IX Region, a large importer of chemicals.

Biological plants versus chemical plants: In various countries they recognize and value the ecological and highly efficient decontamination systems that Chile has been producing to treat wastewater, but the Araucanía Region would be mortgaging its future with dangerous and failed plants.


While primary treatment plants are being spread in the Araucanía Region, questioned by their harmful effects due to chemical use, in a contradictory way, Chile has become one of the main exporters of bio filters (worms) to treat sewage or water. black for the auspicious results obtained, regarding the high efficiency in the removal of organic matter and pathogenic micro-organisms, as well as its low investment and operating costs.

Sewage or sewage is liquid waste from domestic, commercial and industrial use and brings with it a series of organic and inorganic materials. In places where there are sewage systems, they all converge to a sewage collection system, which should end in a treatment plant, as is what is being done in the Araucanía Region through the company Aguas Araucanía, of the holding company Aguas Nuevas (Solari group), who won the state tender to take over this task.

The investment that the company is making is the so-called Sanitation Plan 2005 - 2006, which considers works for 17,530 million pesos in 2005 and 16,519 million pesos for 2006. This plan aims to "treat" the sewage of the region through 17 plants, of which 3 have been built so far (Chol Chol, Gorbea, Renaico); and others such as those of Temuco (15% of construction), Villarrica and Toltén, are currently facing legal actions by the affected rural communities who are trying to paralyze the works and prevent their operation.

The main bases of resistance to these plants are due to discrimination due to their location (100% in Mapuche communities) and the type and quality of plants, of primary treatment, a fact that is unknown by the majority of the regional population. Primary plants, consists of the separation of suspended matter by mechanical means. Only in optimal operating conditions, it is said that it could treat the water between 30 to 40% only. They are commonly made through an artificial lagoon, where the served water converges, with the generation of organochlorines that makes it highly dangerous, since by the interaction of chlorine with organic matter they become toxic compounds. Furthermore, it produces large quantities of sludge that are unusable and will end up in garbage dumps.

Well, these types of plants will be in rural areas coexisting with rural communities and populations and in this way, with this type of treatment, they will be discharged into rivers and their waste to landfills in the region by tons.

Parallel to this regional debacle, various biofilter initiatives have emerged in Chile that have not been considered by the vast majority of "sanitation" companies or the authorities despite their effectiveness and low cost, which operates thanks to the action of worms. The operation of this technique consists in that the organic matter present in the wastewater is degraded by a population of microorganisms and worms adhering to the environment, matter that is absorbed on the biological film or layer of humus, in whose outer layers it is degraded by the aerobic microorganisms and worms. The organic matter that manages to pass the first layer of the biofilter (humus) is subsequently degraded by the anaerobic microorganisms of the sawdust layer. The last layer of stones functions as a low rate trickling filter.

The microorganisms adhering to this medium are aerobic, since the biofilter has air pockets and ventilation in its lower part, which allows a quick evacuation of the treated water and also oxygenation through the lower part of the system. As a result: crystalline, pure and odorless water and by the way, improve the land and agriculture, since through the contribution of worm humus, it is possible to restore damaged lands and layers.

As some experts have pointed out, private sanitation companies do not apply it because there are economic interests involved, however, experimentally, it has been applied for a long time in some localities, there is even an exception in the Araucanía Region since there is a plant belonging to private individuals, of a bio filter type, located in the town of General López, on the way to the commune of Vilcún.

It is worth mentioning that this new sewage treatment technology, which has been around for a few years, has been promoted by the Foundation for Technological Transfer of the University of Chile, which has been known as the Tohá system, in reference to its creator, the Dr. José Tohá, who after various investigations in 1994 carried out his project with the construction of an experimental sewage treatment plant in CEXAS Melipilla for a population of approximately 1,000 people.

This system has obtained awards and various recognitions in different parts of the world, which has meant that at present, the type of worms is exported to different places, for towns and industries, with a great demand.

In Chile, this system is applied in some population places, apart from CEXAS Melipilla of the Metropolitan Region, it is also in the town of El Melón, for 12,000 people, in Los Nogales, V Region; Likewise, in the Campo Lindo Community, for 2,750 people, in El Tabo, V Region; In the Montemar community, 1,250 people, also in El Tabo, V Region; And also, used to treat various types of solid waste from industries in the country, as well as for numerous companies, mainly agro-industry and salmon farming.

Treatment Efficiency

According to the Program for the Decontamination of Sewage Water and Organic Liquid Industrial Waste of the Foundation for Technology Transfer, the process manages to reduce the following parameters: 95% of the BOD, 93% of the Volatile Suspended Solids; 96% of the Volatile Solids; 70% of Nitrogen; 70% of the Phosphorus; 99.9% of fecal coliforms.

Treatment Advantages


According to experts, among its main advantages are: It does not generate sludge, these are transformed into humus; Does not use chemical reagents that harm the environment (chlorine, ozone); It has low operating and investment costs in civil works; Produces biomass and natural fertilizers useful for agriculture; It allows the reuse of treated water for industrial processes and / or irrigation, since it comfortably complies with current environmental regulations for irrigation water.

Comparison Biofilter vs Other Technologies in Sewage Treatment

According to what was reported by the Sewage Decontamination Program and Riles Universidad de Chile, comparing a Biofilter plant with a stabilization lagoon and another with activated sludge, the following differences appear:

Stabilization pond plant

a) Surface: It requires large surfaces to retain the water of a population for 20 days or more.

b) Investment costs: Moderate cost. Typical range 50-80 US $ / room. Land price is not included.

c) Control equipment: Simple, since the system works by gravity

d) Operation and maintenance costs: To meet quality standards and avoid the production of bad odors, chemical elements are used.

e) Maintenance efficiency: Requires significant solar radiation.

Activated sludge plant

a) Surface: It requires less surface than the lagoons but greater than the biofilter.

b) Investment costs: High cost. Price range 100-150 US $ / room. Land price is not included.

c) Control equipment: Complex since it injects air or oxygen under pressure.

d) Operation and maintenance costs: Chemical elements (chlorine) are used to meet quality standards and avoid the production of bad odors. It has a significant energy expenditure for equipment that injects oxygen (air).

e) Maintenance efficiency: It is possible to reach the standard of water suitable for irrigation.

Bio filter plant (earthworms)

a) Surface: It requires very little surface since the water is treated in minutes.

b) Investment costs: Very low costs. It is estimated 15-60 US $ / room. Land price is not included.

c) Control equipment: Simple, since the system works at the field level.

d) Operation and maintenance costs: It does not use chemical elements that damage the environment. Its energy expenditure is minimal: operational cost of the pumping equipment and the radiation chamber.

e) Maintenance efficiency: Very efficient in removing contaminants and pathogenic microorganisms. Reductions greater than 90%. Meets the standard of water suitable for irrigation and discharge to water courses.

In sum, the surface area required by the system is considerably less than stabilization pond systems and its efficiency is higher than that of activated sludge systems currently in use, among many other benefits that have been proven.

* By Alfredo Seguel: Member of the Konapewman Group of Temuco; and the collective of action for environmental rights, Araucanía Region.


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