Quality assessment of drinking water in the communities of São Francisco do Conde, Baiacu, Santo Amaro and Cachoeira
Joseina Moutinho Tavares PhD in Environmental Geology and Master in Chemistry from the Federal University of Bahia - UFBA Specialization in Environmental and Environmental Education and Sanitation Bachelor of Chemistry from the Federal University of Bahia - UFBA Bachelor of Pharmacy in the Dom Pedro II University Center Professor at the Federal Institute of Education, Science and Technology of Bahia (IFBA) Address: Emídio dos Santos Street, Barbalho, Salvador - BA, Brazil E-mail: [email protected]
Anderson Silva de Oliveira Master in Applied Chemistry from the Federal University of Bahia - UFBA Specialization in Activating Change Processes in Higher Education for Health Professionals, Health Management, Pharmaceutical Assistance Management, Hospital Administration and Health Systems Professor at Dom Pedro II University Center Address: 20 Estados Unidos Avenue, Comércio, Salvador - BA, Brazil E-mail: [email protected]
Paulo Moutinho Andrade de Souza Degree in Biology from the Federal University of Bahia - UFBA Master's student in Ecology: Theory, Applications and Values Bachelor of Biological Sciences (UFBA) Member of the Laboratory of Teaching, Philosophy and History of Biology UFBA - Department of Biology Address: 668 Barão de Jeremoabo Street, Campus de Ondina, Salvador - BA, Brazil E-mail: [email protected]
Walter da Silva Junior Biotechnology Student at the Federal University of Bahia - UFBA Address: Reitor Miguel Calmon Avenue, Canela, Salvador - BA, Brazil E-mail: [email protected]
ABSTRACT This work aims to evaluate the quality of drinking water in the communities of Baiacu, São Francisco do Conde, Santo Amaro and Cachoeira. It was verified that in some places of Santo Amaro and São Francisco do Conde, from the microbiological point of view, it is not appropriate for consumption, because it was found that the presence of total coliforms in 50% of the samples and that the chlorine content is below the values indicated by the standards in 75% of the analyzed samples. Thus, the consumption of contaminated water can cause diseases, so it is recommended cleaning of residential reservoirs, maintenance in pipes periodically, as well as the need for continuous monitoring of water quality and the intense participation of public agencies in these actions. Through these actions and the active participation of the population, one can preserve the environment and the lives of all those who transit in the communities of the Bay of All Saints.
Keywords: Water, water quality, chemical and biological contamination.
1 INTRODUCTION One of the major ecological concerns today refers to the environmental impact caused by the anthropic release of toxic metals in the various natural environments and, of greater importance, in those with greater interaction with human populations. This is due to the fact that man, using the power to transform the environment, has rapidly changed the balance of nature. As a result, species were often exposed to dangers that may be irreversible. Underground seas, rivers, lakes and water sheets are the final destination of every soluble pollutant released into the air or soil. Water is extremely important for living beings, since in the very constitution of organisms, a human being has 70% of his body formed by water and, during his life, it is estimated that he consumes around 126,000 liters. The consumption of low quality water decreases people's survival capacity, since contaminants, once absorbed, are not completely eliminated, causing metabolic changes with reduced life time and working capacity. The Bay of All Saints, the largest of the Brazilian coast, is an example of this. Research involving chemical and biological contaminants has grown in recent years as a consequence of occupational and environmental exposures, or disturbances caused by these elements, induced by special disease situations. Thus, water quality is a matter of relevance and concern for public health (LIBANIO, 2010). Adolescents constitute the portion of the population that inspires concern, from the toxicological point of view, because they present greater absorption of contaminants than adults, because their organisms are not fully developed. Environmental studies are indispensable to evaluate the current conditions of a locality mainly in tourist regions (ALMEIDA, 1995). Currently in this Bay that has an area of 1100 km2, few stretches are viable for aquaculture because of pollution. Consequently, these materials can cause damage to human health, obstacles to maritime activities, deterioration of water quality and reduction of possibilities in the field of leisure. This work arose mainly from the need to evaluate the work of the fisherman and people who transit in the communities of Bay of All Saints, since there are no regulatory standards for the fishing professional in the country. The population is subject to a number of specific risks, such as excessive exposure to poisons; among others. Another reality is the possible worsening of the risk
factors of this population caused by the growth of anthropic activities with potential for contamination of water and sediments (BAHIA, 2004). The coastal zone is the region most heavily affected by man-made changes and, due to its intense activity because they are sites close to a large population and agricultural activities, the study of metal contamination in marine sediments is of great public interest. Contaminants, once absorbed by the body, are often not completely eliminated, causing metabolic changes such as reduced life time and working capacity in exposed individuals. The present work aims to obtain data on the incidence of chemical and biological elements in drinking water, as well as metallic elements in sediments on the Bay of All Saints region.
2 METHODOLOGY The methodology used in this research aims to evaluate the environmental status of the communities of Baiacu, São Francisco and Santo Amaro in the Bay of All Saints. The determinations included free chlorine, hardness, ammonia, pH among others and to achieve the desired objectives, the following procedures were performed: (i) Choice of sample points of the regions; (ii) collection of water samples; (iii) treatment of samples; (iv) Chemical treatment of samples and analytical determination of metals; (v) determination of pH, conductivity, free chlorine, ammonia, total hardness, alkalinity, nitrates, nitrites, sulfates and sulfides; (vi) microbiological analyses; (vii) Data processing and map making, using the Method of quantitative representation with Arcgis 10.1 software to facilitate the interpretation and synthesis of the results, associating them with the purpose of the research. The decontamination procedures of the materials were carried out in the Research Laboratory of the Chemistry Department of the Federal Institute of Bahia (IFBA). For decontamination of the material was carried out; (i) washing with neutral, phosphate-free detergent, ensuring total cleaning and without laboratory residues; (ii) the materials for which they were used to determine the metal contents were washed with 5 % nitric acid (v/v) and immersed during the 24-hour period, and at the end of the washing procedure, the materials were rinsed with distilled water and with ultrapure water; (iii) All glassware left for 10 minutes in an ultrasonic bath in the research laboratory of IFBA- Campus Salvador to ensure their cleanliness. The mechanical waves generated in this equipment propagate through any material medium with
frequency greater than 20 kHz and therefore facilitate the cleaning of material. Ultrasonic cleaning technology makes use of cavitation and moment transfer, phenomena induced by the propagation of high intensity acoustic waves, with frequency above the human audible limit (≈ 18 kHz) in liquid media. It is the most efficient of non-abrasive cleaning methods that do not use chemical dissolution of the substrate. During the period covered by the research, bibliographic surveys of research similar to the work in focus, environmental studies on water and metal quality in sediments were conducted in libraries of educational institutions, as well as through the virtual environment. In addition, research was conducted on the history of the region, recent and ancient events that influence the environmental and social environment of the cities. Also old photos of the communities were captured and compared with updated images. Thus, it was possible to visualize some significant changes in the communities of São Francisco do Conde, Santo Amaro, Baiacu and Cachoeira in Bay of All Saints. Table 01 shows the sample points.
Table 1: Identification of sampling points. Sample Points Local (1) Baiacu I (Bai I) (2) Baiacu II (Bai II) (3) Cachoeira I ( Ca I) (4) Cachoeira II ( Ca II) (5) Santo Amaro I (SA I) (6) Santo Amaro II (AS II) (7) São Francisco do Conde I (SFC I) (8) São Francisco do Conde II (SFC II)
The metal analysis was carried out in the Petrochemical Pole company of Camaçari, using the ICP-OES equipment, Model Optima 4300 DV of the Perkin Elmer brand. The determinations of nitrates, nitrites, sulfates and sulfides were performed by the molecular absorption spectrophotometry method, Lambda XLS model, Perkin Elmer brand. Hardness is an organoleptic standard of potability important in both domestic and industrial water and shows the amount of calcium and magnesium mainly. The method used to determine hardness was Complexion Titlemetry in the presence of a
buffer solution (pH 9.5 - 10) and the Black Eriochrome indicator. It was title with EDTA until the red color turn wine to blue (APHA, 2005). The free chlorine contents were performed by the Chemistry Research Laboratory of IFBA using colorimetric techniques, using the Colorimetric method (DPD), in which free chlorine oxidizes the DPD indicator (N,N-dietil-p- phenylenediamine) to form a pink compound proportional to the chlorine concentration in the sample (RODIER, 1975). Microbiological analyses were performed by the chromogenic substrate method, with confirmed results for the presence of total coliforms and E. coli in 24 hours. The method is based on the specific enzymatic activities of coliforms (ß galactosity) and E. coli (ß glucoronidase). The culture media contain indicator nutrients (chromogenic substrate) which, hydrolyzed by coliform-specific enzymes and, or, E. coli, cause a color change in the medium – yellow, in the case of coliforms, or produce fluorescence when the sample is exposed to ultraviolet light, in the case of E. coli. Heterotrophic bacteria were determined by the filter membrane technique (MINISTÉRIO DA SAÚDE, 2011).
3 RESULTS AND DISCUSSIONS According to Table 2, the samples from Cachoeira, Santo Amaro and São Francisco do Conde (Samples 3, 4, 6 and 7) showed positive results for total coliforms and for Escherichia coli (Samples 3 and 4). The results reveal biological contaminations and that the presence of bacteria is seen as an indicator of fecal contamination in drinking water. Drinking water must not contain pathogenic microorganisms and should be free of bacteria insignia of fecal contamination. The presence of the total coliform bacteria group denotes that there was an external interference in the drinking water, since this group of bacteria is not part of the chemical composition of the drinking water. Therefore, it can be said that the water that presents total coliforms is not pure, that is, it can be contaminated by external agent.
Table 2: Results of microbiological analyses of drinking water in the regions under study. Heterotrophic Escherichia Samples Total coliforms bacteria. Coli 35°C (UFC/mL) (1) Ba I Absence Absence 2.0 x 10 (2) Ba II Absence Absence 2.0 x 10 (3) Ca I Presence Presence 5.5 x 10
(4) Ca II Presence Presence 5.2 x 10 (5) SA I Absence Absence 2.5 x 10 (6) SA II Presence Absence 1.0 x 10 (7) SFC I Presence Absence 6.0 x 10 (8) SFC II Absence Absence 4.0 x 10
Table 3: Results of physicochemical analyses of drinking water in the regions under study. Analysis Ba I Ba II Ca I Ca II Sa I Sa II SFC I SFC II Reference*
Ph 6,60 6,50 7,77 8,04 7,38 7,70 6,90 6,60 6.0 to 9.5 Apparent color 20 20 10 12 5 5 5 10 15 (uHZ)
N-NH3(mg/L) 1,3 1,0 2,0 1,5 1,0 0,5 1,5 1,0 1,5 Hardness 24 28 56 56,6 84 88 74 82 500 (mg/L CaCO3) Free chlorine 2,0 2,0 0,10 0,05 < 0.1 < 0.1 < 0.1 < 0.1 0.2 to 2.0 (mg/L) Sulfate (mg/L) 3,125 2,987 0,019 0,074 1,230 1,411 1,337 1,474 250
Sulfide (mg/L) 0,078 0,023 0,048 0,030 0,065 0,011 0,069 0,045 0,1
Nitrate (mg/L) 2,850 2,112 1,868 3,074 1,839 2,356 0,690 1,465 10
Nitrite 0,324 0,721 0,225 0,463 0,379 0,235 0,468 0,819 1,0 *Ordinance No. 2,914/2011 of the Ministry of Health
Table 3 shows that the results of pH, Hardness, Sulfate, Sulfide, Nitrate and Nitrite are below the reference values. However, samples 1 and 2 showed high apparent color. It is known that the apparent color of water may come from organic matter, tannins, metals or strongly colored industrial waste. The color in public water supply systems is aesthetically undesirable and that the water sample of Baiacu is in unsatisfactory conditions, since they presented apparent color in disagreement with potability standards. The samples from the communities in focus presented free chlorine contents below the reference values, possibly indicating that the water is unfit for human consumption. Chlorine is a bactericidal agent, so Ordinance No. 2,914/2011 of the Ministry of Health determines the obligation to remain between 0.2 mg/L to 2 mg/L of residual chlorine. In drinking water distribution systems, the quality of this can undergo a series of changes, causing the quality of the water in the user's tap to differ from the quality of the water that leaves the treatment plant. Such changes can be caused by chemical and biological variations or by a loss of system integrity. Some factors that influence such changes include: chemical and biological quality of the water source;
effectiveness of the treatment process, reservoir (storage) and distribution system; age, type, design and maintenance of the network; quality of treated water. The absence of Cl favors the proliferation of coliforms and bacteria, thus corroborating the positive values obtained in bacteriological analyses. Thus, it is recommended to continuously monitor water quality, since the physical-chemical and microbiological parameters are indicators of the integrity of the distribution system, showing that water can cause serious diseases such as: gastroenteritis, urinary infection, cystitis and etc. (DONNEMBERG, 2014, SILVA, 2016).
4 FINAL CONSIDERATIONS The data reveal that the water consumed in some places of Santo Amaro and São Francisco do Conde, from the microbiological point of view, is not appropriate for consumption, because it was found that the presence of total coliforms in 50 % of the samples and that the chlorine content is below the values indicated by the standards in 75% of the samples analyzed. Thus, the consumption of contaminated water can cause diseases, so it is recommended cleaning of residential reservoirs, maintenance in pipes periodically, as well as the need for continuous monitoring of water quality and the intense participation of public agencies in these actions. In this way, it is possible to guarantee the preservation of the environment and the life of all those who transit in the communities of São Francisco do Conde, Baiacu, Cachoeira and Santo Amaro of the Bay of All Saints.
ACKNOWLEDGMENTS We thank the Federal Institute of Education, Science and Technology of Bahia (IFBA), the Federal University of Bahia and the Dom Pedro II University Center for their support and encouragement.
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