Published

2024-02-25

Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca

Remoción de Helicobacter pylori a través de sistemas de tratamiento por filtración en gravas en el municipio de Popayán, Cauca

DOI:

https://doi.org/10.15446/ing.investig.100573

Keywords:

Helicobacter pylori, gravel filtration, multi-stage filtration technology, rural water supply (en)
Helicobacter pylori, filtración en gravas, filtración en múltiples etapas, acueducto rural (es)

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Authors

Multi-stage filtration technology (MSFT) is an alternative that reduces the risk of fecal contamination, allowing for reliable water purification in rural water supplies. MSFT is composed of two gravel filtration (GF) stages: one including dynamic gravel filters (DyGF) and up-flow gravel filters (UGF), and a final stage with slow sand filters (SSFs). However, with the purpose of reducing construction costs, this technology is partially implemented, leaving SSFs for a later construction stage and limiting its treatment potential. To evaluate the removal capabilities regarding fecal contamination (especially that by the pathogen H. pylori) of a two-stage GF system, the quality of raw and treated water and the hydraulic parameters of Los Llanos treatment system (municipality of Popayán, Cauca) were monitored for 15 weeks. This system is operated and maintained by the community. The results showed the removal efficiency regarding turbidity to be 16% (p=0,045) and 34% (p=0,030) for the DyGF and the UGF, respectively. The color removed by the DyGF reached 19% (p=0,033), and the UGF reported a value of 30% (p=0,041). The reduction of total coliforms was limited by the system’s operation and maintenance, exhibiting a tendency towards increased concentrations at the outlet. The presence or absence of H. pylori was determined via the PCR molecular technique. A greater presence was evidenced in treated water than in raw one, which may be associated with a limited operation and a low maintenance frequency of the system. The implementation of MSFT, without the complement of SSFs, is not reliable in ensuring quality of water, particularly from a perspective of microbiological control and H. pylori control.

La tecnología de filtración en múltiples etapas (FIME) es una alternativa que reduce el riesgo por contaminación fecal, permitiendo la potabilización del agua de manera confiable en acueductos rurales. La tecnología FiME está compuesta por dos etapas de filtros en grava (FG): una que incluye filtros dinámicos (FGDi) y filtros gruesos ascendentes (FGAC), y una etapa final con filtros lentos en arena (FLA). Sin embargo, con el fin de reducir los costos de construcción, esta tecnología se implementa de manera parcial, dejando los FLA para una etapa posterior de construcción y limitando su potencial de tratamiento. Con el fin de evaluar la capacidad de remoción de la contaminación fecal (especialmente del patógeno H. pylori) en un sistema de FG de dos etapas, se monitoreó durante 15 semanas la calidad del agua cruda y tratada y los parámetros hidráulicos del sistema de tratamiento Los Llanos en el municipio de Popayán, Cauca, el cual es operado y mantenido por la comunidad. Los resultados mostraron que la eficiencia de remoción respecto a la turbiedad es de 16 % (p=0,045) y 34 % (p=0,030) para el FGDi y el FGAC respectivamente. El color removido por el FGDi alcanzó el 19 % (p=0,033), y el FGAC reportó un valor de 30 % (p=0,041). La reducción de los coliformes totales se vio limitada por la operación y mantenimiento del sistema, presentando una tendencia a incrementar su concentración en la salida. La presencia o ausencia del H. pylori se determinó con la técnica molecular PCR. Se evidenció una mayor presencia en agua tratada que en agua cruda, lo cual puede asociarse con una limitada operación y una baja frecuencia de mantenimiento del sistema. La implementación de la tecnología FiME, sin el complemento de FLA, es poco confiable para garantizar la calidad del agua, particularmente desde el punto de vista microbiológico y el control del H. pylori.

Recibido: 19 de enero de 2022; Aceptado: 24 de julio de 2023

ABSTRACT

Multi-stage filtration technology (MSFT) is an alternative that reduces the risk of fecal contamination, allowing for reliable water purification in rural water supplies. MSFT is composed of two gravel filtration (GF) stages: one including dynamic gravel filters (DyGF) and up-flow gravel filters (UGF), and a final stage with slow sand filters (SSFs). However, with the purpose of reducing construction costs, this technology is partially implemented, leaving SSFs for a later construction stage and limiting its treatment potential. To evaluate the removal capabilities regarding fecal contamination (especially that by the pathogen H. pylori) of a two-stage GF system, the quality of raw and treated water and the hydraulic parameters of Los Llanos treatment system (municipality of Popayán, Cauca) were monitored for 15 weeks. This system is operated and maintained by the community. The results showed the removal efficiency regarding turbidity to be 16% (p=0,045) and 34% (p=0,030) for the DyGF and the UGF, respectively. The color removed by the DyGF reached 19% (p=0,033), and the UGF reported a value of 30% (p=0,041). The reduction of total coliforms was limited by the system's operation and maintenance, exhibiting a tendency towards increased concentrations at the outlet. The presence or absence of H. pylori was determined via the PCR molecular technique. A greater presence was evidenced in treated water than in raw one, which may be associated with a limited operation and a low maintenance frequency of the system. The implementation of MSFT, without the complement of SSFs, is not reliable in ensuring quality of water, particularly from a perspective of microbiological control and H. pylori control.

Keywords:

Helicobacter pylori, gravel filtration, multi-stage filtration technology, rural water supply.

RESUMEN

La tecnología de filtración en múltiples etapas (FIME) es una alternativa que reduce el riesgo por contaminación fecal, permitiendo la potabilización del agua de manera confiable en acueductos rurales. La tecnología FiME está compuesta por dos etapas de filtros en grava (FG): una que incluye filtros dinámicos (FGDi) y filtros gruesos ascendentes (FGAC), y una etapa final con filtros lentos en arena (FLA). Sin embargo, con el fin de reducir los costos de construcción, esta tecnología se implementa de manera parcial, dejando los FLA para una etapa posterior de construcción y limitando su potencial de tratamiento. Con el fin de evaluar la capacidad de remoción de la contaminación fecal (especialmente del patógeno H. pylori) en un sistema de FG de dos etapas, se monitoreó durante 15 semanas la calidad del agua cruda y tratada y los parámetros hidráulicos del sistema de tratamiento Los Llanos en el municipio de Popayán, Cauca, el cual es operado y mantenido por la comunidad. Los resultados mostraron que la eficiencia de remoción respecto a la turbiedad es de 16 % (p=0,045) y 34 % (p=0,030) para el FGDi y el FGAC respectivamente. El color removido por el FGDi alcanzó el 19 % (p=0,033), y el FGAC reportó un valor de 30 % (p=0,041). La reducción de los coliformes totales se vio limitada por la operación y mantenimiento del sistema, presentando una tendencia a incrementar su concentración en la salida. La presencia o ausencia del H. pylori se determinó con la técnica molecular PCR. Se evidenció una mayor presencia en agua tratada que en agua cruda, lo cual puede asociarse con una limitada operación y una baja frecuencia de mantenimiento del sistema. La implementación de la tecnología FiME, sin el complemento de FLA, es poco confiable para garantizar la calidad del agua, particularmente desde el punto de vista microbiológico y el control del H. pylori.

Palabras clave:

Helicobacter pylori, filtración en gravas, filtración en múltiples etapas, acueducto rural.

Introduction

In a worldwide systematic review by Hooi et al. (2017), it was revealed that 60% of the population is infected with Helicobacter Pylori (H. pylori), with variations in distribution. The regions with developing countries that show the highest prevalence of this infection are Africa (79,1%), Latin America and the Caribbean (63,4%), and Asia (54,7%), contrasting with a lower prevalence in developed countries in North America (37,1%) and Oceania (24,4%).

H. pylori infection is acquired by the population before the age of ten, and its prevalence increases with age (Ramos and Sánchez, 2009). In Colombian children, it is close to 75%, and, in the population older than 20, it reaches 86% (Moncayo et al., 2006). The incidence of this pathogen is related to gastric cancer figures. In Colombia, it represented 13,7% of all cancer deaths in the country, being the first cause in men and the third in women. The highest risk of mortality was reported in the departments of Quindío, Huila, and Cauca for men and in Cauca, Norte de Santander, and Huila for women (Pardo et al., 2017; Adrada et al., 2008).

Three routes of diffusion have been considered for this bacterium, oral-oral, gastro-oral, and fecal-oral (Aziz et al., 2015; Bartram and Cairncross, 2010; Goh et al., 2011). However, for the latter, water is considered as an intermediate vehicle for transmission, acting as an environmental reservoir (Hulten et al., 1996; Engstrand, 2001). Its presence was reported in surface sources used in water supply systems in Venezuela (Adrada et al., 2008; Fernández-Delgado et al., 2008) and, more worryingly, in water from storage tanks and in water distribution systems for consumption in Peru (Hulten et al., 1996), Portugal (Gião et al., 2008), United States (Baker and Hegarty, 2001), Mexico (Premoli et al., 2004), Costa Rica (Campos et al., 2011; Montero-Campos, 2019), Iran, and Pakistan (Samra et al., 2011; Al-Sulami et al., 2010), thus confirming the presence of the pathogen in drinking water as an important source of transmission. Additionally, some studies provide evidence that surface waters may contain considerable levels of viable H. pylori cells, (Acosta et al., 2018; Agustí et al., 2010; Santiago, 2016).

In Colombia, H. pylori has been found in the water sources used in the public supply systems of cities such as Bogotá (Vesga, 2018), as well as in rural areas of the department of Cauca (Ordóñez, 2015). In addition, the purification treatments used have great operating limitations in small municipalities, particularly in rural areas, where the necessary infrastructure for water treatment is non-existent or has only been partially implemented. This entails negative impacts on the quality of the water, which was reflected on the Water Quality Risk Index (IRCA) of 2019. This index showed low risk values for urban areas (5,73%) and medium risk values for the rural sector (16,23%). These figures do not include self-sufficiency, since most rural water supplies have not been legalized, and 42,4% of these systems are classified as having high risk (Ministerio de Vivienda, Ciudad y Territorio, 2020), evidencing a great gap between urban and rural areas in terms of the quality of water for human consumption.

The use of MSFT depends on the water sources' degree of contamination. This method can comprise two or three stages of filtration, i.e., dynamic gravel filters (DyGF), up-flow gravel filters (UGF), and slow sand filters (SSF) (Galvis, 1999). The first two stages make up the pretreatment phase, which allows reducing the concentration of suspended solids as well as microbiological contamination. Upon reaching the SSF, a more effective removal of the remaining microbiological contaminants is achieved via biological predation mechanisms. Finally, low-turbidity waters are produced, which are virtually free of enterobacteria, enterovirus, and protozoan cysts (S. Haig, 2014; Haig et al., 2011; Sánchez et al., 2007; Raman et al., 1992). MSFT is considered to be a simple, reliable, and efficient technology that is suitable for rural communities due to its ease of operation and maintenance.

Considering a gradual and progressive approach, the implementation of this technology could be carried out in two phases. In the first phase, the pretreatment system would be built (DyGF and UGF), while, the SSFs would be constructed in the second one (Galvis et al., 1992; Galvis, 1999; Galvis et al., 1999; Sánchez et al., 2007).

Numerous studies carried out in Colombia and different parts of the world have shown that the combination of pretreatment systems involving gravel and slow sand filters yields water with low sanitary risk for users (Mushila et al., 2016; Vega, 2013; Nkwonta and Ochieng, 2009; Sánchez et al., 2007; Fernández et al., 2006; Ochieng et al., 2004; Galvis, 1999; Wegelin, 1996; Galvis et al., 1992). In all the aforementioned studies, pre-treatment systems have been able to achieve water qualities that would allow applying gradualness and progressiveness in rural treatment systems of water for human consumption, which could benefit the development of projects when there are no resources for a full implementation of MSFT.

MSFT is considered to be highly efficient in the elimination of pathogens, but there are no studies on the removal of H. pylori using this technology, much less in gravel prefiltration systems (DyGF and UGF), which, despite their high microbiological removal capabilities, may not be enough to achieve optimal levels of potability.

This research presents the results obtained by monitoring the removal of H. pylori in water pretreated with gravel filtration in Los Llanos water supply system in the municipality of Popayán, Cauca.

Methodology

This full-scale study was carried out at the drinking water treatment plant in the village of Los Llanos, which is part of Las Guacas water supply system and is located in the northeastern part of the municipality of Popayán.

The water treatment plant is composed of a DyGF, followed by a layered UGF (Figure 1 ). It does not have SSFs or employ a chlorination stage as a disinfection method. The raw water supply comes from the Velasquillo and San Isidro streams.

Scheme of treatment plant and gravel size

Figure 1: Scheme of treatment plant and gravel size

Source: Authors

Water quality monitoring

The physical-chemical and microbiological quality of the water was monitored by analyzing the parameters shown in Table 1.

Table 1: Measurement protocol for water quality parameters

Parameter Unit of measurement Equipment Method
Turbidity Nephelometric turbidity units (NTU) Turbidity meter HACH 2100P (HACH, USA) Nephelometric (SM 2130B)
Color Platinum-cobalt units (PCU) Spectrophotometer HACH DR2010 (HACH, USA) Spectrophotometric (SM 2120C)
pH Dimensionless pH-meter (HACH, USA) Potentiometric (SM 4500H + B),
Flow L/s. Volumetric material and stopwatch Volumetric method (Ministry of the Environment, 2007)
Head loss cm Piezometers Difference of levels
Total coliforms and E. coli CFU/100ml Membrane filtration equipment, laminar flow chamber, incubator Membrane filtration, code: TP0314 IDEAM

Source: Authors

Considering the configuration of the plant, the sampling points were as follows: i) raw water, ii) mixture of the effluent water from the two dynamic filters, and iii) outlet of the layered UGF. Physical and hydraulic parameters were measured twice a week, and microbiological aspects were evaluated once a week, for a total of 15 weeks.

By means of a macro-drip system, 500 mL of water were collected for 30 min in amber glass containers and sterilized via a Gemmyco S232 autoclave at 121 °C for 15 min. They were transported, in portable refrigerators at 4 °C to the Applied Human Genetics laboratory of Universidad del Cauca, where they were processed for later Helicobacter pylori analysis. They were also transported to the SENA-Cauca's Environmental Analysis Laboratory, where the presence of total coliforms and E. coli was determined. Physical parameters were measured in the field. As operating control parameters of the treatment plant, the flow treated by the filtration units and the head losses were measured in the UGF.

Microbiological contamination indicators

The total coliforms and E. coli were measured by filtering 100 mL of water through sterile cellulose membranes with 0,45 urn pores and 47 mm in diameter (S/PAD, MS, MCE squared membrane, Sterile White). Chromocult Coliform Agar was used as the culture medium. As positive controls for E. coli and total coliforms, the Escherichia coli ATCC 25922 strain was used, in addition to Pseudomona aeruginosa ATCC 10145 strain as a negative control.

Helicobacter pylori detection

The water samples were concentrated by centrifugation in two stages. A first step at 4 000 rpm and 8 °C for 30 min (Heraeus Megafuge 1.0R centrifuge) was carried out to reach a concentration volume of 4,5 mL. Previously resuspended, this volume was transferred to 1,5 mL microcentrifuge tubes, which were in turn centrifuged at 12 000 rpm for 5 min, eliminating the supernatant until final volumes of 200 uL were obtained. This was done using an Eppendorf 5415C centrifuge.

Subsequently, DNA extraction was carried out. The concentrates were processed using the E.Z.N.A. Water DNA kit (Omega Bio-Tek, Doraville, USA) while following the manufacturer's recommendations. The isolated DNA was eluted in 200 μL of buffer solution and stored at -20 °C until amplification.

DNA amplification was carried out by means of polymerase chain reaction (PCR), using specific primers previously reported for H. pylori: VacA si/s2, VacA m1/m2, and CagA (Atherton et al., 1995; Erzin et al., 2006; Yamaoka et al., 1999). Additionally, PCR specificity was verified using DNA from three strains of H. pylori (TX30a, 11638, and 11637). The amplification mix contained 0,36 μL of each primer (Mm), 5 μL of Qiagen Multiplex PCR, prepared according to the manufacturer's recommendations, and 7 μL of genomic DNA. The PCR tubes were briefly centrifuged at low speed in order to bring the entire sample to the bottom of the tube. The samples were taken to the thermal cycler (MyCycler Thermal Cycler, BIORAD) under the conditions shown in Table 2.

Table 2: PCR conditions for amplification

Step Process T (°C) Time Cycles
1 Initial denaturation 95 10 min 1
Denaturation 94 30 s
2 Coupling 57 90 s 15
Extension 70 45 s
Denaturation 94 30 s
3 Coupling 54 1 min 25
Extension 72 1 min
4 Final extension 72 5 min 1

Source: Authors

Finally, the amplified DNA was visualized in 1,5% agarose gels in 1X TAE buffer (Tris-Acetic-EDTA), using EZ-VISION THREE as a dye. Gel electrophoresis was performed at 80 V for 60 min. The presence of the amplified fragments was verified by visual inspection on the Gel DocTM XR + Imaging System (BIO-RAD, USA), taking the amplification bands of strain 11637 as reference.

The data were processed in the STATGRAPHICS Centurion XVI.I statistical software. The maximum efficiency of each filtration unit was determined through hypothesis tests, with a confidence level of 95% regarding the turbidity and color parameters. The reduction of microbiological characteristics (total coliforms and E. coli) was performed in logarithmic units.

Results and discussion

Raw water quality

The turbidity of the raw water ranged between 1,6 and 12,7 NTU, the average apparent color was 39,6 UPC, the total coliforms and the the average E. coli were 1 213 and 103 CFU/100 mL, respectively, the average temperature was 18,8 °C, and the pH ranged from 6,6 to 7,5. These quality conditions were recommended by Galvis et al. (1999) for the use of MSFT systems with DyGF, UGF, and SSF plus disinfection as a safety barrier. However, the treatment system only has the first two stages, which is usable within a scheme of progressivity for improving water quality if disinfection is performed collectively or individually in the households.

Treatment system operation

In general, some operating conditions limited the proper functioning of the different treatment structures. The DyGF did not exhibit a water level over the filter bed, which does not allow blocking the turbidity peaks that occur in raw water during the rainy season due to the dragging of solids in the basin. The flow treated by the plant during the study period was 3,05 L/s, which corresponded to a filtration rate of 2,94 m/h in the DyGF. Meanwhile, in the studied UGF, the treated flows per unit ranged between 0,84 and 2,04 L/s, with an average of 1,52 L/s, which represents a filtration rate range of 0,53-1,14 m/h, with an average value of 0,85 m/h. These rates are above those recommended (0,30 and 0,60 m/h) by Galvis et al. (1999), which may entail reduced removal efficiency and increased maintenance requirements due to a greater hydraulic head loss in the UGF.

It can be highlighted that there were periods of low maintenance frequencies in the treatment units, with an impact on hydraulic head losses. During the first five weeks, the UGF reached hydraulic head loss values of up to 4,7 cm, with large amounts of mud on the filter surface generated by a very low frequency of maintenance, which included only two bottom drainages without surface washing. Figure 2a shows substantial sludge buildup on the surface filter medium, while Figure 2b illustrates a clean filter medium.

Gravel filter with presence of mud on the surface. a) week 3; b) week 10.

Figure 2: Gravel filter with presence of mud on the surface. a) week 3; b) week 10.

Source: Authors

During the following five weeks, the maintenance frequency was increased to once a week, with deep washing and superficial washing every two weeks, showing reductions in hydraulic head loss (from 4,7 to 2,1). For the last four weeks of monitoring, the frequency of maintenance was reduced again (no bottom drainage or surface washing was evidenced), yielding a much greater increase in hydraulic head loss (between 2,6 and 5,8 cm).

These data, particularly those between the first five weeks and the last four, indicate that there was an accumulation of sludge within the filter medium of the UGF.

Treated water quality

The results obtained regarding turbidity, color, total coliforms, and E. coli are summarized in Table 3. None of these parameters reached the average quality value suggested by the World Health Organization (WHO, 2017) for drinking water, which shows low or no removal efficiency. These statistical results were obtained with a confidence level of 95%, through which the removal efficiency was estimated (Table 4).

Table 3: Quality of raw water and effluent of DyGF and UGF

Parameter Statistical Raw water DyGF UGF
Average 3,8 3,3 2,3
Turbidity - SD 2,1 1,4 1,0
Maximum 12,7 7,3 5,9
Minimum 1,6 1,9 1,4
Average 39,6 32,8 26,3
Apparent SD 21,7 17,0 16,5
Color Maximum 92,3 67,0 67,7
Minimum 8,3 7,7 3,7
Average 1 213 1 343 1 184
Total SD 732 958 736
Coliforms Maximum 3 300 4 100 3 069
Minimum 483 154 392
Average 103 83 57
E. coli SD 71 63 39
Maximum 263 239 148
Minimum 5 20 8
Total samples 30 30 30
H. pylori Number of positives 3 6 6

Source: Authors

Table 4: Efficiency of the filters in the removal and reduction of the parameters

* Includes only the values that caused reductions.

Source: Authors

As per the statistical analysis, with regard to turbidity and color, the DyGF exhibited removal values lower than 16 and 19%, respectively (Table 4). These results are consistent with the efficiency of other MSFTs treating similar raw water qualities. Galvis et al. (1999) reported a removal efficiency ranging from 24 to 38% for turbidity and between 17 and 21% for color. However, these values were obtained under appropriate DyGF operating and maintenance conditions.

In the case of the UGF, the results indicate removal values of less than 34,0% for turbidity and 30% for color (Table 4), while the same study by Galvis et al. (1999) reported 31-36% for turbidity and 21-26% for color, with a filtration rate of 0,6 m/h, lower than that of our study. Posso (2012) reported 32 and 36% turbidity removals in the Golondrinas and Arroyohondo plants, respectively, with filtration rates between 0,45 and 0,57 m/h. This indicates that the UGF units under study exhibit a similar removal efficiency, despite the higher filtration rates used.

The results obtained regarding the removal of total coliforms and E. coli (Tables 3 and 4) show great variation and low performance in the filtration units. In 71% of the cases, there was a tendency towards an increased concentration of total coliforms at the outlet of the DyGF. In the remaining 29%, a reduction of 0,17 log was observed. The UGF exhibited a similar but less accentuated trend, with a reduction of 0,22 log for 64% of the cases (Table 4).

The performance of the DyGF in the removal of E. coli also exhibited limitations, as reductions were only achieved in 57% of the cases, reaching a value lower than 0,22 log (Table 4). Meanwhile, the UGF, managed to obtain reductions of less than 0,3 log for 79% of the cases. These results evidence the low performance of the system when compared to the reduction of microorganisms through gravel filters (Mushila et al., 2016; Vega, 2013; Nkwonta and Ochieng, 2009; Sánchez et al., 2007; Fernández et al., 2006; Galvis et al., 1999; Posso, 2012), where removals and/or reductions between 30 and 40% and between 0,6 and 2,5 log have been reported, The behavior of the studied units was favored by the environmental conditions caused by inadequate operation and maintenance,

The removal of particles in a gravel filter occurs by different mechanisms, with sedimentation being one of the most important. The efficiency of the filter depends on variables such as the filtration speed, the length and size of the filter medium, porosity, and the particle size to removed (Boller, 1993; Sánchez, 2017). The adherence of the particles to the surface of the filter medium is given by the interaction between van der Waals attraction forces and hydrodynamics. The accumulation of particles inside the pores reduces their size, which entails increased interstitial flow velocity, hydraulic head losses, and shear forces that allow for the detachment of the retained particles (Boller, 1993). Sánchez (2017) found that particles less than 5 um in diameter can only be removed with efficiencies between 45 and 70% and a filtration rate of less than 0,5 m/h.

In this sense, the low or null efficiency found especially in the removal of coliforms and E. coli could be explained by the detachment of accumulated excess particles inside the gravel filters, which is caused by the low frequency of maintenance and high filter operation speeds (0,53-1,14 m/h), likely entailing shear forces large enough to generate drag in the retained particles and cause increases in both turbidity and color, as well as in the concentration of microorganisms, as described by Boller (1993).

Helicobacter pylori removal

The presence of H. pylori was detected in 15 of the 90 samples taken during monitoring. Three samples correspond to raw water, six to the outlet of the DyGF, and another six to the outlet of the UGF (Table 5). Considering that the bacteria can survive in water by employing several strategies, including the formation of biofilm (Campos et al., 2011; Moreno et al., 2007; Santiago, 2016; Chowdhury, 2012; Watson et al., 2004), conversion to coccoid form in a non-cultivable viable state (CVNC) (Azevedo et al., 2007; Oliver, 2005), or adherence to abiotic surfaces (Fernández et al., 2008), their greater presence at the outlet of the filters could be associated with the possible detachment of retained solids due to the high cutting forces generated by the accumulation of particles in the gravel. However, this finding should be studied in more detail.

Table 5: Presence ( + )/absence (-) of H. pylori per week

Maintenance activities:

* Two bottom drainages without surface washing

** Weekly bottom drainages with surface washing

*** Without bottom drainages or surface washing

Source: Authors

As shown in Table 5, during weeks 1 to 5 and 12 to 15, in which maintenance was not adequately carried out, nor with the frequency required for this type of filtration units, the number of samples with presence of H. pylori was greater at the outlet of the gravel filters (DyGF and UGF). On the other hand, between weeks 6 and 11, during which maintenance activities were performed more frequently, no positive values were detected.

Statistical analysis revealed a relationship between the lack of filter maintenance and the presence of Helicobacter pylori, with p-values of 0,036 and 0,018 for the DyGF and the UGF respectively. Meanwhile, no significant differences were found in terms of color, turbidity, E. coli, and total coliforms removal, with p-values greater than 0,27.

Conclusions

The results obtained for the studied system's operating conditions do not show significant microorganism removal (coliforms and Helicobacter pylori). On the contrary, there is a greater number of positive values at the outlet than at the inlet. It should be noted that the operation and maintenance of the treatment system was mostly inappropriate, which could explain the results. In general, when they are well operated and maintained, these systems are expected to improve quality of water. Thus, it is evident that the selection and implementation of treatment technologies must be thoroughly considered according to local conditions. In our case, the partial introduction of MSFT in Los Llanos water supply system, despite the fact that its operation and maintenance scheme is much simpler than that of other technologies, does not seem to be sufficient to guarantee a good quality of water for human consumption if interventions that facilitate the appropriation of technology by the community are not considered. Similarly, without the complement of SSFs, MSFT seems to be unreliable in ensuring water quality, particularly from a microbiological point of view.

These results also show that applying the concept of graduality to rural water treatment systems, which considers the construction of staged systems, must ensure quality of water for all users. This should also be complemented with disinfection techniques.

Although the findings regarding microbiological removal are linked to a low frequency of maintenance, a more detailed study is required to better explain the presence of H. pylori at the outlet of the filters.

Acknowledgments

The authors express their gratitude to the project titled Validation of slow sand filters for the removal of the emerging pathogen Helicobacter pylori in rural water supply systems, which is attached to the call for the funding of projects aimed at strengthening research groups classified in category C, which are recognized and registered by the Vice-Principalship for Research of Universidad del Cauca. The authors would also like to thank the community of Los Llanos, which is part of Las Guacas water supply system, for their valuable support in the execution of our research activities; as well as the Environmental Engineering and Human Genetics laboratory of Universidad del Cauca and the SENA-Cauca Environmental Analysis Laboratory.

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Campos M, Soto H, Meléndez M, Sandoval C, Santamaría G, Rojas B, Cascante L, Gutiérrez O, Montero Campos V. Hallazgo de la bacteria Helicobacter pylori en agua de consumo humano y su relación con la incidencia de cáncer gástrico en Costa Rica. Tecnología en Marcha. 2011;2433-14.

Chowdhury S. Heterotrophic bacteria in drinking water distribution system: A review. Environmental Monitoring and Assessment. 2012;1846087-6137. https://doi.org/10.1007/s10661-011-2407-x [Link]

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Erzin Y, Koksal V, Altun S, Dobrucali A, Aslan M, Erdamar S, Dirican A, Kocazeybek B. Prevalence of Helicobacter pylori vacA, cagA, cagE, iceA, babA2 genotypes and correlation with clinical outcome in Turkish patients with dyspepsia. Helicobacter. 2006;116574-580. https://doi.org/10.1111/j.1523-5378.2006.00461.x [Link]

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Fernández J, Cruz A, Benavides E. Remoción de materia orgánica por filtración en múltiples etapas. Ingeniería Hoy. 2006;2420-27.

Galvis G, Visscher JT, Lloyd B. Multi-stage surface water treatment for community water supply in Colombia. Waterlines. 1992;10326-29. https://doi.org/10.3362/0262-8104.1992.008 [Link]

Galvis G. Development and evaluation of multistage filtration plants: An innovative, robust and efficient water treatment technology. doctoral thesis. University of Surrey. 1999. https://openresearch.surrey.ac.uk/esploro/outputs/doctoral/Development-and-evaluation-of-multistage-filtration/99513881902346 [Link]

Galvis G, Latorre J, Visscher JT. Filtración en múltiples etapas: tecnología innovativa para el tratamiento de agua. Artes Gráficas de Univalle. 1999. https://www.ircwash.org/sites/default/files/255.9-99FI-17025.pdf [Link]

Gião MS, Azevedo NF, Wilks SA, Vieira MJ, Keevil CW. Persistence of Helicobacter pylori in heterotrophic drinking-water biofilms. Applied and Environmental Microbiology. 2008;74195898-5904. https://doi.org/10.1128/AEM.00827-08 [Link]

Goh K, Chan W, Shiota S, Yamaoka Y. Epidemiology of Helicobacter pylori infection and public health implications. Helicobacter. 2011;161-9. https://doi.org/10.1111/j.1523-5378.2011.00874.x [Link]

Haig S. Characterising the functional ecology of slow sand filters through environmental genomics. doctoral thesis. University of Glasgow. Glasgow. 2014. https://theses.gla.ac.uk/5523/1/2014HaigPhD.pdf [Link]

Haig SJ, Collins G, Davies RL, Dorea CC, Quince C. Biological aspects of slow sand filtration: Past, present and future. Water Science and Technology: Water Supply. 2011;114468-472. https://doi.org/10.2166/ws.2011.076 [Link]

Hooi JKY, Lai WY, Ng WK, Suen MMY, Underwood FE, Tanyingoh D, Malfertheiner P, Graham DY, Wong VWS, Wu JCY, Chan FKL, Sung JJY, Kaplan GG, Ng SC. Global prevalence of Helicobacter pylori infection: Systematic review and meta-analysis. Gastroenterology. 2017;1532420-429. https://doi.org/10.1053/j.gastro.2017.04.022 [Link]

Hulten K, Han SW, Enroth H, Klein PD, Opekun AR, Gilman RH, Evans DG, Engstrand L, Graham DY, El-Zaatari FAK. Helicobacter pylori in the drinking water in Peru. Gastroenterology. 1996;11041031-1035. https://doi.org/10.1053/gast.1996.v110.pm8612990 [Link]

Ministerio de Vivienda Ciudad y Territorio. Informe Nacional de Calidad del Agua para Consumo Humano INCA 2019. 2020. https://www.minvivienda.gov.co/sites/default/files/documentos/informe-calidad-de-agua-2019.pdf [Link]

Moncayo JI, Santacruz JJ, Álvarez AL, Franco B, López MA, Ángel A, Gallego ML, Serrano H. Comparación de métodos diagnósticos en la infección por Helicobacter pylori en Quindío, Colombia. Colombia Médica. 2006;373203-212. https://www.redalyc.org/articulo.oa?id=28337306 [Link]

Montero-Campos V. Helicobacter pylori en Costa Rica, más de una década de investigaciones. Revista Tecnología en Marcha. 2019;3294-103. https://doi.org/10.18845/tm.v32i9.4636 [Link]

Moreno Y, Piqueres P, Alonso JL, Jiménez A, González AFM. Survival and viability of Helicobacter pylori after inoculation into chlorinated drinking water. Water Research. 2007;41153490-3496. https://doi.org/10.1016/j.watres.2007.05.020 [Link]

Mushila CN, Ochieng GM, Otieno FAO, Shitote SM, Sitters CW. Hydraulic design to optimize the treatment capacity of multi-stage filtration units. Physics and Chemistry of the Earth. 2016;9285-91. https://doi.org/10.1016/j.pce.2015.10.015 [Link]

Nkwonta O, Ochieng G. Roughing filter for water pre-treatment technology in developing countries: A review. International Journal of Physical Sciences. 2009;49455-463. https://www.researchgate.net/publication/237827490_Roughing_filter_for_water_pre-treatment_technology_in_developing_countries_A_review [Link]

Ochieng GMM, Otieno FAO, Ogada TPM, Shitote SM, Menzwa DM. Performance of multistage filtration using different filter media against conventional water treatment systems. Water SA. 2004;303361-367. https://doi.org/10.4314/wsa.v30i3.5085 [Link]

Oliver JD. The viable but nonculturable state in bacteria. Journal of Microbiology. 2005;4393-100.

Ordóñez JF. Evaluación de la calidad microbiológica de las fuentes de abastecimiento del acueducto rural El Saladito - Timbío - Cauca. undergraduate thesis. Universidad del Cauca. Popayán. 2015. http://repositorio.unicauca.edu.co:8080/xmlui/handle/j123456789/6862 [Link]

Pardo C, De Vries E, Buitrago L, Gamboa Ó. Atlas de mortalidad por cáncer en Colombia. 2017. https://www.cancer.gov.co/ATLAS_de_Mortalidad_por_cancer_en_Co-lombia.pdf [Link]

Posso D. Análisis de la operación y mantenimiento de la filtración en gravas de flujo ascendentes a escala real. undergraduate thesis. Universidad del Valle. Cali. 2012. https://hdl.handle.net/10893/7675 [Link]

Premoli G, González A, Millán-Mendoza B, Percoco T, Vielma A. Diagnóstico de Helicobacter pylori mediante la reacción en cadena de la polimerasa. Revista Cubana de Medicina Tropical. 2004;56285-90. http://scielo.sld.cu/pdf/mtr/v56n2/mtr01204.pdf [Link]

Raman A, Paramasivam R, Heijnen HA, Visscher J. Filtración lenta en arena: tratamiento de agua para comunidades: planeación, diseño, construcción, operación y mantenimiento. IRC. 1992. https://es.ircwash.org/resources/filtracion-lenta-en-arena-tratamiento-de-agua-para-comunidades-planeacion-diseno [Link]

Ramos AR, Sánchez RS. Contribución de Latinoamérica al estudio del Helicobacter pylori. Acta Gastroenterológica Latinoamericana. 2009;393197-218. https://www.redalyc.org/exportarcita.oa?id=199317345011 [Link]

Samra ZQ, Javaid U, Ghafoor S, Batool A, Dar N, Athar MA. PCR assay targeting virulence genes of Helicobacter pylori isolated from drinking water and clinical samples in Lahore metropolitan, Pakistan. Journal of Water and Health. 2011;91208-216. https://doi.org/10.2166/wh.2010.169 [Link]

Sánchez LD, Sánchez A, Galvis G, Latorre J. Filtración en Múltiples Etapas. IRC. 2007. https://es.ircwash.org/resources/filtracion-en-multiples-etapas [Link]

Sánchez LD. Determinación del factor de adherencia en filtros de grava de flujo ascendente en capas. Ingeniería y Competitividad. 2017;192121-130. https://doi.org/10.25100/iyc.v19i2.5299 [Link]

Santiago P. Transmisión de Helicobacter pylori a través del agua: estudio de la presencia del patógeno e identificación de formas viables mediante técnicas moleculares. doctoral thesis. Universidad Politécnica de Valencia. Valencia. 2016. https://doi.org/10.4995/thesis/10251/75086 [Link]

Vega Serrano HA. Evaluación del sistema de filtración en múltiples etapas FiME en tanques plásticos con pre-sedimentación y retro-lavado en la hacienda Majavita (Socorro, Santander). master's thesis. Universidad de Manizales. Manizales. 2013. https://ridum.umanizales.edu.co/xmlui/bitstream/handle/20.500.12746/151/402_Vega_Serrano_Haimar_Ariel_2013_Documento.pdf [Link]

Vesga F. Detección y viabilidad de Helicobacter pylori en aguas crudas y potables en tres plantas de potabilización en la ciudad de Bogotá. doctoral thesis. Pontificia Universidad Javeriana, Universidad Politécnica de Barcelona. Bogotá. 2018. https://doi.org/10.11144/Javeriana.10554.41877 [Link]

Watson CL, Owen RJ, Said B, Lai S, Lee JV, Surman-Lee S, Nichols G. Detection of Helicobacter pylori by PCR but not culture in water and biofilm samples from drinking water distribution systems in England. Journal of Applied Microbiology. 2004;974690-698. https://doi.org/10.1111/j.1365-2672.2004.02360.x [Link]

Wegelin M. Surface water treatment by roughing filters: A design, construction and operation manual. SKAT. 1996. https://www.ircwash.org/resources/surface-water-treatment-roughing-filters-design-construction-and-operation-manual [Link]

World Health Organization (WHO). Guidelines for drinking-water quality: fourth edition incorporating the first addendum. WHO. 2017. https://www.who.int/publications/m/item/guidelines-for-drinking-water-quality-4th-ed.-incorporating-the-1st-addendum-(chapters) [Link]

Yamaoka Y, Kodama T, Gutiérrez O, Kim JG, Kashima K, Graham DY. Relationship between Helicobacter pylori iceA, cagA, and vacA status and clinical outcome: Studies in four different countries. Journal of Clinical Microbiology. 1999;3772274-2279. https://doi.org/10.1128/jcm.37.7.2274-2279.1999 [Link]

1 CRediT author statement All authors contributed to the conceptualization, methodology, validation, formal analysis, investigation, data curation, and writing of this work. They have approved the definitive version of this manuscript for publication

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Mushila, C. N., Ochieng, G. M., Otieno, F. A. O., Shitote, S. M., and Sitters, C. W. (2016). Hydraulic design to optimize the treatment capacity of multi-stage filtration units. Physics and Chemistry of the Earth, 92, 85-91. https://doi.org/10.1016/j.pce.2015.10.015

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How to Cite

APA

Ledezma, C., Fernández, J., Acosta, P. & Leyton , J. (2024). Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca. Ingeniería e Investigación, 44(1), e100573. https://doi.org/10.15446/ing.investig.100573

ACM

[1]
Ledezma, C., Fernández, J., Acosta, P. and Leyton , J. 2024. Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca. Ingeniería e Investigación. 44, 1 (Jan. 2024), e100573. DOI:https://doi.org/10.15446/ing.investig.100573.

ACS

(1)
Ledezma, C.; Fernández, J.; Acosta, P.; Leyton , J. Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca. Ing. Inv. 2024, 44, e100573.

ABNT

LEDEZMA, C.; FERNÁNDEZ, J.; ACOSTA, P.; LEYTON , J. Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca. Ingeniería e Investigación, [S. l.], v. 44, n. 1, p. e100573, 2024. DOI: 10.15446/ing.investig.100573. Disponível em: https://revistas.unal.edu.co/index.php/ingeinv/article/view/100573. Acesso em: 11 aug. 2026.

Chicago

Ledezma, Cristina, Javier Fernández, Patricia Acosta, and Javier Leyton. 2024. “Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca”. Ingeniería E Investigación 44 (1):e100573. https://doi.org/10.15446/ing.investig.100573.

Harvard

Ledezma, C., Fernández, J., Acosta, P. and Leyton , J. (2024) “Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca”, Ingeniería e Investigación, 44(1), p. e100573. doi: 10.15446/ing.investig.100573.

IEEE

[1]
C. Ledezma, J. Fernández, P. Acosta, and J. Leyton, “Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca”, Ing. Inv., vol. 44, no. 1, p. e100573, Jan. 2024.

MLA

Ledezma, C., J. Fernández, P. Acosta, and J. Leyton. “Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca”. Ingeniería e Investigación, vol. 44, no. 1, Jan. 2024, p. e100573, doi:10.15446/ing.investig.100573.

Turabian

Ledezma, Cristina, Javier Fernández, Patricia Acosta, and Javier Leyton. “Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca”. Ingeniería e Investigación 44, no. 1 (January 2, 2024): e100573. Accessed August 11, 2026. https://revistas.unal.edu.co/index.php/ingeinv/article/view/100573.

Vancouver

1.
Ledezma C, Fernández J, Acosta P, Leyton J. Helicobacter pylori Removal through Gravel Filtration in a Water Treatment System of the Municipality of Popayán, Cauca. Ing. Inv. [Internet]. 2024 Jan. 2 [cited 2026 Aug. 11];44(1):e100573. Available from: https://revistas.unal.edu.co/index.php/ingeinv/article/view/100573

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CrossRef citations1

1. Javier Leyton, Javier Fernández, Patricia Acosta, Andrés Quiroga, Francesc Codony. (2024). Reduction of Helicobacter pylori cells in rural water supply using slow sand filtration. Environmental Monitoring and Assessment, 196(7) https://doi.org/10.1007/s10661-024-12764-2.

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Copyright (c) 2024 Cristina Ledezma, Javier Fernández, Patricia Acosta, Javier Leyton

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