What environmental problem is the article trying to solve? What is the problem with drinking water according to the article? How does the technique proposed in the article promote a sustainable economy and the preservation of the environment?
What environmental problem is the article trying to solve? What is the problem with drinking water according to the article? How does the technique proposed in the article promote a sustainable economy and the preservation of the environment?
What environmental problem is the article trying to solve? What is the problem with drinking water according to the article? How does the technique proposed in the article promote a sustainable economy and the preservation of the environment?
(NOTE: The first 2 pages of this article are attached as image, the next one is written here:
Technical aspects:Filtration has been used since the 19th century, when the slow sand filtration process was generally the only method of water treatment. Slow sand filtration has the quality of separating pathogens and improving the aesthetic appearance of the water. The removal of pathogenic agents was not known in the 19th century. An example of the ignorance of this characteristic is related to events that occurred in 1892, in which 8,500 people died in Hamburg, as a result of a cholera epidemic. Hamburg used untreated water from the Elbe river, but its Altara suburb treated the water by sedimentation and slow sand filtration and did not suffer from the cholera epidemic. Filtration systems can be classified by:
Gravity or pressure: gravity filtration is the process in which water is passed through a filter, and the process is carried out by the effects of gravity. Pressure filters are contained in containers and the water flows through the filter media under pressure.
Filtration speed: fast, slow or variable. Slow filtration is one that occurs at speeds between 0.1 and 0.2 m/h, while fast filtration occurs at speeds between 5 and 20 m/h.
Cake or depth filtration: cake filtration is the process in slow sand filters, in which, on the surface of the filter, a filter cake develops and filtration, through that surface, is by physical mechanisms. and biological. Depth filtration occurs when most of the thickness of the filter media is active for the filtration process and the quality of the filtrate improves with depth. It is the case of quick filters It's sand.
Slow sand bed filtration is experiencing a renaissance, as it has recently been shown to improve microbiological water quality, and has separation rates of up to 99.9% for Giardia and Cryptospiridium cysts. This system may become popular again, as Giardia cysts are known to have some resistance to chlorination.
Separation of impurities is considered to take place in the biological layer. The effective size of sand grains is 0.2mm and this effectively retains all particles larger than 0.02mm. Giardia cysts are about this size, thus filtering into the biological layer.
There is some conflicting discussion as to whether the biolayer is essential in the separation of Giardia, as some research has shown that Giardia is removed in sand filters that do not have a fully developed biolayer. According to research by Logsdon and Fox (1988), slow sand filtration significantly improves water quality parameters.
The separation of total coliform bacteria was 99.4% or greater. This rate depended on bed depth and decreased with depth. Cysts between 7 and 12 µm in size had separation rates of 96.8% or greater. Particle size 1 at 60 µm was 98.1 or larger.
The removal of color is not significant with separation rates only around 25%, the decrease in turbidity with high rates and values that are reduced to 0.5 NTU.
The cleaning, which is a process to remove the biological layer, and start the process again, lasts two days.
Improvement of the biofiltration process The scientific interest that the slow filtration process has regained is due to the use of other materials for the formation of the filter bed, which are a powerful resource available to engineering when it comes to presenting an alternative to design an urban wastewater treatment plant.
In general, this technique offers the following advantages:
Reduces pathogenic germs in the water by up to 100%.
High ratio between the available surface area and the volume occupied by the new filter bed materials (synthetic fibres), together with a high value of hollow spaces, facilitates greater filter performance and, at the same time, better mechanical operation.
It occupies little space, is easy to operate and maintain and can be applied to any population center, regardless of size.
Reduces residual chlorine levels in the drinking water distribution network.
This system is cheaper than traditional systems.
conclusion
The biofiltration process, due to its high efficiency in the water purification process, should be the subject of study and research in order to improve its design, management and maintenance operations. The foregoing presupposes economic benefits that, in turn, would favor the conditions of the populations with the need to satisfy their drinking water requirements.
What environmental problem is the article trying to solve? What is the problem with drinking water according to the article? How does the technique proposed in the article promote a sustainable economy and the preservation of the environment? Do you think it would be beneficial if the proposal presented in the article were replicated in your country? Justify your answer.
Transcribed Image Text:Biofiltration, an alternative for water purification Álvaro Arango Ruiz Chemical Engineer.
Research line: Water treatment, SIGMA Management and Environment research hotbed
Biofiltration, an alternative for water purification
Summary
Abstract In current times, the population from developing countries is experiencing a lack of basic sanitary conditions, including the potable
water to satisfy their needs. The lack of water potabilization is associated with illness and death among children because of hydric origin diseases.
The lack of water available and properly treated for human use, brings the need to get interested in innovative projects in this field, as
biofiltration, introducing efficient treatment, potabilization and distribution alternatives which must be easy to be reached and economically
viable for the people.
Keywords: Potable water. Water purification. Biofiltration. Bioremediation. Slow filtration.
Introduction
The Second National Inventory of Water Quality carried out in 1998 reported that only seven out of ten municipalities had good quality water1,
reflecting this sanitary condition in the Health Situation in 2001, in which 22 out of every 100,000 Colombian children under the age of five died
of acute diarrheal disease.
Given the prevailing need of the population, especially small communities in developing countries, to continuously and efficiently have drinking
water, it is necessary to resort to the study and proposal of new alternatives for water purification, alternatives that are accessible and
economically viable, that satisfy the demand for water for domestic use.
In this article, a review and analysis of the biofiltration process will be made as an alternative that guarantees a state of adequate basic sanitation
for the affected populations, thus improving their quality of life. It is known that biofiltration uses a single operation for water purification,
presenting physical and biochemical processes as a consequence of low filtration rates, which generate the formation of a biolayer on the surface
of the bed, a layer responsible for removing and/or retaining pathogens.
Although biofiltration is a very old and used technique, what makes it attractive today is the use of new materials that replace those used in
traditional granular media, thus improving its competition against other treatment alternatives. The variations that could be made to the process
show a subject little explored worldwide, constituting a novel study.
Global picture
Currently, one of the greatest needs of the world population is the availability of drinking water to have an optimal quality of life, essential for
fair, sustainable and healthy development for any country. In developing countries, there is a lack of drinking water for various reasons, among
which are the lack of water resources, the contamination of water sources or even financial problems, which do not allow the implementation of
treatment systems., purification and distribution of water to the population.
Continuing with the developing countries, it can be affirmed that there are innumerable problems that result from the deficiencies of basic
sanitation, such as the availability of drinking water, sanitary removal and the disposal of solid waste, for which we find the following statistics :
Poverty and basic sanitation problems are responsible for the death of a child every 10 seconds. According to a United Nations report, 1.1 billion
people around the world live without clean water. The figure increases in a chilling way when talking about how many people live in unworthy
health conditions: there are 2,400 million men and women without access to decent health facilities for the standard parameters of world health.
The consequence is predictable but no less painful for that. Every year, 2.2 million people die in the world due to diseases linked to contaminated
water, such as diarrhea, cholera, poliomyelitis and amebiasis, among others, as shown in table 1.
Table 1. Waterborne diseases.
Cause
Bacteria
Virus
Parasites
Illness
Diarrhea
Cholera
Typhoid
Poliomyelitis
Hepatitis A
Amoebiasis
Dracunculiasis
Bilarciasis
Millions of sick people
4,000
0.04
0.70
8
2000
400
100
200
Transcribed Image Text:Likewise, 80% of illnesses and 33% of deaths are due to the drinking water crisis. Thus, 65% of hospitalizations and 80% of medical
consultations are caused by gastrointestinal diseases.
25% of the population in developed countries do not have access to drinking water or a sewage network. In developed countries (urban areas)
82.5% have access to water networks and 63.1% to sewerage networks, but 70% of poor countries do not have treated water and 80% live
without connection to sewerage networks.
In 1996, the global demand for water was 5,692 km3/year against a supply of 3,745 km3/year (use of viable potential estimated at 14,000
km3/year).
Today, the world population is four times greater than it was 100 years ago, while water consumption has multiplied by 9 and the need for
industrial water by 40.
Water can be considered a non-renewable resource in that its quantity is limited, and, additionally, the hydrological cycle causes water to present
variable amounts over time and location. This is why it is important that populations resort to the collection, storage and treatment of water to
meet their basic needs, including drinking water.
Developing countries have great difficulties in supplying water to satisfy all their needs. While the industrialized countries have practically solved
their supply, a situation described in table 2.
Table 2. Percentages of water supply
Place
Third World
Chinal
Industrial States
Everybody
1980
40
100
100
64
1985
48
100
100
67
1990
52
100
100
71
2000
61
100
100
75
2010
68
100
100
80
In relation to the information available and referring to Colombia, the quality of water for human consumption is deficient, due to the content of
pathogenic germs and contaminants of physicochemical origin.
A study carried out in Colombia in 1993 by the Ministry of Health and the Pan American Health Organization (PAHO) determined that, in the
group of most important public health diseases, 44% are related to basic sanitation and of these, approximately 40%, are directly related to
drinking water.
According to the Superintendence of Public Services, which carries out inspection, control and surveillance tasks, there are 870 municipalities in
Colombia, with a population of less than 12,500 inhabitants, which present major problems in the supply of water, for not complying with the
provisions of the Decree 475 of 1998.
According to the same study, in 578 municipalities, belonging to 18 departments, drinking water is being supplied that meets the admissible
values of the Decree in a range between 95 and 100% to 5,058,410 inhabitants, which is equivalent to 42.19%.
As for the large cities with more than 500,000 inhabitants, they supply water to their population with an acceptability percentage of 99%,
complying with Decree 475. At the national level, the problem of drinking water quality is centered on smaller municipalities., rural areas,
villages and districts, where the infrastructure and the minimum requirements to guarantee the supply with the frequency and quality established
in the standard are lacking.
In relation to costs, investments in the drinking water and basic sanitation sector in Colombia, despite being high, have not achieved the expected
positive impact on the quality of life of the inhabitants, thereby generating a high waste of resources. economic. Consequently, the problem is
greater in rural areas and in small and medium-sized municipalities, since there is no water supply with some type of adequate storage.
Biofiltration, an alternative for purification
Biological filtration represents a different option to the physicochemical processes, traditionally used for the purification of water. This
biofiltration process is one of the oldest that has been applied in the treatment of water for urban use, and its objective is the separation of
objectionable particles and microorganisms water, which have not been retained by other processes.
Biofiltration can be carried out in porous media or in granular media such as sand or anthracite, among others. Recently, studies have been carried
out with a view to improving the process, replacing the materials of the filter media, replacing them with fibrous media.
This system has the particularity that it purifies the water in a single operation, through the development of physical and bio-chemical processes
that allow, with the application of low filtration rates, the formation of a biological layer on the surface of the bed, which retains suspended
particles and pathogenic microorganisms, thus removing undesirable material to give the water drinking characteristics.
Study of lifeforms too small to see with the naked eye, including bacteria, viruses and protozoans. Microbiologists may study bacteria, yeast, or other microbes to understand better their reproduction, life cycle, or role in causing disease.
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