Hazard assessment and categorization of microbiological risk in a water treatment and distribution system located in a municipality in the interior of Minas Gerais, Brazil

Motta, Marcelo Barbosa; Neumann, Elisabeth

doi:10.4136/ambi-agua.2450

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ARTICLES • Rev. Ambient. Água 15 (3) • 2020 • https://doi.org/10.4136/ambi-agua.2450 copy

Hazard assessment and categorization of microbiological risk in a water treatment and distribution system located in a municipality in the interior of Minas Gerais, Brazil

Avaliação de perigos e categorização do grau de risco microbiológico em um sistema de tratamento e distribuição de água localizado em um município do interior de Minas Gerais, Brasil

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Consumption of non-potable water is a relevant public health problem due to the possibility of transporting numerous chemical and microbiological contaminants. In 2005, the Brazilian Ministry of Health created the National Program of Surveillance in Environmental Health related to the Quality of Water for Human Consumption (VIGIAGUA), with the primary purpose of managing risks related to water supply to human populations in Brazilian territory. However, VIGIAGUA does not have a methodology capable of characterizing or managing risks. The objective of this research is to create a working model to transform raw data into conceptual data related to low-, medium- and high-risk levels. The data used in the application of the model were obtained through the analyses of water-quality surveillance conducted by the Regional Health Management of Itabira, a municipality with less than 10 thousand inhabitants, whose history of water contamination is alarming. Twelve samples/month were collected between May 2017 and April 2018. The results of the treated water analyses were classified according to the presence of hazards and categorized into risk levels. The results showed 83.3% contamination by total coliforms at the treatment plant and 91.6% in the distribution system. The Escherichia coli contamination was 16.7% in the treatment plant samples and 45.2% in the distribution system. The system was categorized as "High Risk". The analysis of untreated water samples was carried out for the purpose of knowing the contamination pattern of the raw water of the region, finding 100% contamination by total coliforms and 97.2% contamination by E. coli.

Keywords:
surveillance health; water analysis; water quality

Priority areas	N	Ӯ	Ỹ
School - 1	6	2.77±4,74	0.95
Department of Public Administration - 1	6	2.20±3,26	0.95
Department of Public Administration - 3	6	1.22±1,19	0.84
Health Center - 1	6	1.05±0,96	0.80
CRSA	6	1.05±1,49	0.57
TS - 2 Treatment station	12	0,92±0,88	0.79
Department of Public Administration - 2	6	0,88±0,74	0.79
Department of Public Administration - 4	6	0,70±0,60	0.46
Hotel	6	0,69±0,51	0.60
School - 3	6	0,67±0,62	0.48
Department of Public Administration - 6	6	0,65±0,46	0.55
School - 2	6	0,61±0,62	0.49
Health Center - 2	6	0,61±0,70	0.34
Department of Public Administration - 5	6	0,59±0,63	0.35
TS - 1 Treatment station	12	0,56±0,65	0.28
School - 4	6	0,24±0,19	0.26
Total samples collected x positive	108
Average	6.7
Standard deviation	2.0

Instituto de Pesquisas Ambientais em Bacias Hidrográficas Instituto de Pesquisas Ambientais em Bacias Hidrográficas (IPABHi), Estrada Mun. Dr. José Luis Cembranelli, 5000, Taubaté, SP, Brasil, CEP 12081-010 - Taubaté - SP - Brazil
E-mail: ambi.agua@gmail.com

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[1] *Corresponding author: Marcelo Barbosa Motta, e-mail: marcelobarbosamotta@gmail.com

Áreas prioritárias	N	nEc	IB_Ec%	Ӯ	Ỹ
Health Unit - Isolated urban area	12	12	100.0	1.56±2.09	1.28
School - Isolated urban area	12	12	100.0	1.10±1.09	0.53
CRSA - Isolated urban area	12	11	91.7	2.25±3.54	0.86
Total samples collected x positive	36	35	97.2

Aspects related to the potability standard
Rated item	Treatment effect		Distribution system
Compliance with the minimum sampling plan - total coliforms	Meets 100%		Meets 100%
Compliance with the minimum sampling plan - free residual chlorine	Meets 100%		Meets 100%
Compliance with the minimum sampling plan - turbidity	Meets 100%		Meets 100%
Evaluation of the bacteriological quality of water: total coliforms	83.3% Presence		91.6% Presence
Evaluation of bacteriological quality of water: E. coli	16.7% Presence		45.2% Presence
Evaluation of water quality: turbidity	24 samples analyzed. 6 samples above 1Tu = 25%		2 samples above 5Tu
Evaluation of water quality: free residual chlorine	Does not attend		Does not attend
Aspects of a general nature - Statistical treatment
Statistically significant difference for the presence of total coliforms in the distribution system in treated water area during rainy/dry periods		Unwanted outcome
Statistically significant difference for the presence of E. coli in the distribution system in treated water area in the rainy/dry periods		Unwanted outcome
Statistically significant difference for turbidity in the distribution system in the area with treated water in the rainy/dry periods		Unwanted outcome
Statistically significant difference for turbidity between TS-1 and TS-2 in rainy/dry periods		Unwanted outcome
Statistically significant difference for turbidity between TS-1 and TS-2 (May/ 17 to Apr/18)		Unwanted outcome
High risk
Subtitle:
Low risk		Attendance to all basic parameters of potability in the treatment exit and distribution system
Medium Risk		Attendance to all the basic parameters of potability at the treatment exit, associated to the no attendance of the parameter for total coliforms in the distribution system.
High risk		Non-compliance with the defined parameter for E. coli.

Priority areas	N	n	BI_TC%
School - 2	6	6	100.0
Department of Public Administration - 1	6	6	100.0
Department of Public Administration - 3	6	6	100.0
Health Center - 1	6	6	100.0
School - 4	6	6	100.0
Department of Public Administration - 4	6	6	100.0
Health Center - 2	6	6	100.0
TS - 1 Treatment station	12	10	83.3
TS - 2 Treatment station	12	10	83.3
School - 1	6	5	83.3
Department of Public Administration - 2	6	5	83.3
CRSA	6	5	83.3
School - 3	6	5	83.3
Department of Public Administration - 5	6	5	83.3
Department of Public Administration - 6	6	5	83.3
Hotel	6	5	83.3
Total samples collected x positive	108	97	89.8
Average	6.7	6.0
Standard deviation	2.0	1.6

Priority areas	N	n	BI_Ec%
School - 2	6	6	100.0
Health Center - 1	6	5	83.3
Health Center - 2	6	5	83.3
Department of Public Administration - 2	6	4	66.7
CRSA	6	4	66.7
Department of Public Administration - 3	6	3	50.0
Department of Public Administration - 4	6	3	50.0
School - 1	6	2	33.3
TS - 1 Treatment station	12	2	16.7
TS - 2 Treatment station	12	2	16.7
Department of Public Administration - 1	6	1	16.7
School - 3	6	1	16.7
School - 4	6	1	16.7
Department of Public Administration - 5	6	1	16.7
Department of Public Administration - 6	6	1	16.7
Hotel	6	1	16.7
Total samples collected x positive	108	42	38.9
Average	6.7	2.6
Standard deviation	2.0	1.7