Drinking Water and Sanitation in Central America - ACS Publications

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Chapter 4

Drinking Water and Sanitation in Central America: Challenges, Perspectives, and Alternative Water Treatment Irwing M. Ramírez-Sánchez,1 Susan Doll,2 and Erick R. Bandala*,1 1Grupo de Investigación en Energía y Ambiente, Posgrado en Ciencias del Agua, Universidad de las Américas Puebla, Sta. Catarina Mártir, Cholula, Puebla, 72810, Mexico 2Department of Sustainable Technology and the Built Environmental, Appalachian State University, Boone, North Carolina, 28608, U.S.A. *E-mail: [email protected]. Tel: +52 222 2292652.

Although the Central America region has no widespread water shortage, water resources are uneven or inadequately distributed and despite the current lack of data for the region, it is estimated that 2.1 million urban and 13.2 million rural inhabitants have no access to safe drinking water. In addition, the use of pit latrines, septic tanks and direct discharges to water bodies are frequent practices. In some countries of Central America, the money spent by the government on treating diarrheal disease is four times the amount of money required to monitoring water quality and improve water sanitation systems. For this reason, this chapter analyzes plausible alternatives for water treatment and wastewater sanitation aimed to improve population’s health by assuring access to safe drinking water. Water treatment alternatives considered for the Central America region are centralized and non-centralized systems. Finally, challenges and perspectives for the region are addressed based on interventions of low-cost water technologies, education about safety practices and proposals for Governments in implementing water management strategies.

© 2015 American Chemical Society In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Introduction Water is one of the most important elements for public health. A target of the Millennium Development Goals is to reduce by half the proportion of the population without sustainable access to safe drinking water and basic sanitation. While the United Nations has recognized the human right to safe water and sanitation, water supply depends on the amount of available water, the legal, economic and social framework, and the engineered distribution system (1). Central America is the geopolitical region that connects North America and South America and includes Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama. The settlement patterns in Central America have changed from historically predominantly rural to now nearly equal urban as shown in Table 1. The overall population is 46.5 million habitants (2) and shows differential increasing rates across countries. The demographic changes have modified the economic structure of the countries within the region, producing effects on social and environmental-related issues, i.e. the lower importance of agriculture’s contribution to gross domestic product (GDP) or imbalance between water supply and water demand (3). The main runoff in Central America is to the Pacific coast (c.a. 30 % of total water) being this region where the most intensive economic development and over 70 % of population occur (3) giving water resources unevenly between rural and urban areas, as also showing in Table 1. As shown in Table 1, urban access to drinking water is uniformly greater then 86% with rural access considerably lower in all countries, especially El Salvador and Nicaragua. Overall, 2.1 million urban and 13.2 million in rural areas of Central America have no access to drinking water. Similarly, with the exception of Costa Rica, access to adequate sanitation is significantly lower in rural areas particularly in Belize. Total affected populations are 1.1 million and 8.7 million in urban and rural areas, respectively. In order to avoid the undesirable consequences of the lack of access to safe drinking water, poor and marginalized groups in the countries of the region may pay more than 25% of their monthly-earned incomes to get drinking water from independent suppliers. The low level of water supply service is usually correlated with the regions with extreme poverty, whereas wealthy regions usually have access to high-quality water services (9). The water stress at the household and community levels can be compared using the Water Poverty Index (WPI) (10), that links household welfare with water availability and indicates the degree of impact on human populations due to water scarcity. The lower the WPI value, the higher the impact of water scarcity on human populations. The WPI values for countries in Central America are also shown in Table 1 (5). In agreement with the index values included, El Salvador shows the highest water stress and Costa Rica has the lowest degree of water scarcity. Water quantity, however, is not the only complex topic in the region. In Central America, most countries do not have water quality monitoring systems or regulations to forbid the use of dangerous chemicals such as pesticides, or to reduce the pollution due to agricultural practices, industry activities, or services sector (3). As a result, the impact of the presence of undesirable toxic chemicals in drinking water is poorly understood or completely unknown. 54 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Table 1. Central America Population Distribution, Access to Drinking Water and Sanitation, and Water Poverty Index Value (WPI). Data source: references (4) and (5). Population, %

Drinking water, %

Sanitation, %

Country

Urban

Rural

Urban

Rural

Urban

Rural

WPI

Belize

50.36

49.64

99.60

62.70

70.90

25.30

66.3

Guatemala

34.98

65.02

87.34

47.91

94.72

70.31

59.3

El Salvador

50.75

49.25

86.30

16.70

85.76

50.38

55.9

Honduras

46.55

53.45

89.00

63.20

93.98

49.50

60.2

Nicaragua

53.62

46.38

88.26

14.43

93.00

56.00

58.2

Costa Rica

43.11

56.89

99.47

81.44

88.76

97.13

66.8

Panama

55.21

44.79

86.75

76.15

98.65

86.54

66.5

Even though rarely differentiated in official drinking water data, Halder et al. (6) have proposed two different source types to be considered in water supply services: improved or unimproved drinking water. Improved drinking water sources includes the use of household connections, public standpipes, boreholes, protected dug wells, protected springs, and rainwater collection. Unimproved drinking water sources include unprotected wells, unprotected springs, rivers or ponds, vendor-provided water, bottled water (due to potential limitations in quantity), and tanker truck water. The global ratio of inhabitants using improved drinking water is 83%, whereas in Latin America this value drops to 40 % (6). Inadequate or poor drinking water quality is highly correlated with diarrheic illnesses. In Central America, the population sector with the highest mortality rate, related to diarrheic diseases associated with poor water quality, is children aged one to four years old. The mortality rate per 1000 inhabitants varies for the different countries in the region and has been reported as high as 1.9 in Costa Rica, 2.4 in El Salvador, 4.1 in Nicaragua, 5.3 in Honduras and 8.6 in Guatemala (7). These numbers are two orders of magnitude higher when compared with other developing countries in Latin America where the mortality rate per 100,000 inhabitants are 1.1 in Chile and Cuba and 3.1 in Mexico. Due to the lack of access to water sources with the proper water quality in the different countries within the region, women and children spend several hours daily collecting water from polluted sources that in many cases are far away from their communities and/or in hard to access locations. The time wasted in collecting water reduces the time that could otherwise be invested in activities such as household chores, child care, education, farming or any other productive activities. As usually happens in poor and developing countries (8), women and girls are responsible for assuring the supply and treating water for household consumption (9). 55 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

The aim of this chapter is to analyze the situation in the Central American region related to drinking water quality and wastewater sanitation in order to identify the main challenges, suggest some perspectives, and propose cost-effective alternatives for the management and enhancement of water quality that may help the sustainable development of the region.


Drinking Water and Sanitation in Central American Countries Available data for drinking water and sanitation are summarized below for all the countries included within the Central American region. The information was classified and organized to provide a complete set of information for understanding the problem complexity occurring in the study area. Belize Surface and groundwater resources in the country are adequate to avoid further water supply shortages. However, despite the water availability, water quality is becoming a major concern. Even though 97% of the population has access to drinking water, only 11% of inhabitants in urban areas have accesses to sewerage service. In the rural sector, 87% of the population has access to only rudimentary water facilities, i.e. pit latrines, and septic tanks, as the most common forms of sanitation infrastructure (11). As a result of this situation, the risk of surface and underground water being polluted by the poorly treated or completely untreated sewage water increases as the wastewater discharges increase. The urgency of implementing cost-effective wastewater treatment processes is clear in the case of Belize to maintain the viability of its sustainable growth and improve the quality of life of inhabitants. Guatemala Although the available per capita water resources in Guatemala is higher than 9.7 x 1010 m3 per year, the entire country lacks access to safe drinking water because of pollution and rain seasonality in the country. The actual water infrastructure reaches only 1.5 % of the available water (12). According to Guatemala’s Statistical Institute, drinking water and sanitation coverage in the country are 73.5 and 55.96 % respectively. Significant reductions when comparing data before and after the damage caused by hydro-meteorological events, combined with the lack of investment in public infrastructure, indicate that improvement in public services has fallen behind population growth. Based on official data, coliform bacteria are found in more than 90% of surface water in the country, and only 15% and 25 % of the water supplied is treated for disinfection (improved water source) in rural and urban areas, respectively (9). The amount of municipal wastewater discharge is nearly 668 million cubic meters (Mm3) but only 6% is treated. This situation significantly contributes to the frequency of waterborne diarrheic diseases, lack of nutrition and high mortality within the population sector younger than five years old. 56 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

El Salvador


Almost no information is available related to water quality, water pollution, wastewater discharge, or treatment. Surface water quality monitoring in 55 rivers across the country has shown that the entire country does not have any water source with excellent water quality, and that only 12% of the surface water is considered good, 50% is considered as regular, 31 % is bad and 7% is indexed as terrible (13). As shown, significant improvement are required in El Salvador not only to generate basic information on the surface water quality but also related to underground water quality, wastewater quality and quantity, as well as wastewater production and treatment. Honduras In Honduras, the reported population coverage for drinking water in urban areas is 82% and 72% for sanitation. For rural areas, these data become 68% and 64%, respectively. Drinking water disinfected by chlorine in rural areas covers only 32% of the population (14), and only 52% of individuals living in rural Honduras use improved water sources. As a result, the country has a mean of 18.6 episodes of diarrhea per child-year in children less than five years old (6). Nicaragua Information about water quality, wastewater generation, and treatment in Nicaragua is also almost nonexistent. Nevertheless, diarrheic diseases are reported commonly present all around the country where household sanitation is not in common use. In some areas, mortality due to diarrheic diseases accounts for 7.3% of the overall mortality every year. There is no sanitation infrastructure and it has been proposed by some authors (15) that simple and low-cost interventions such as improve microbiological water quality by chlorination and latrine infrastructure development to reduce wastewater effluents may reduce the prevalence of diarrheic diseases in isolated regions of Nicaragua. Costa Rica In Costa Rica, 98.3 % of the population receives drinking water, but only 82% receives it from improved water sources (16). Drinking water from improved sources frequently includes disinfection by filtration or settling when needed (1). Another problem of drinking water services is the disruption of water supply resulting in the need for bringing the water by truck. It is estimated that approximately 800 thousand inhabitants receive water from unimproved water sources (1). Pathogen contamination from untreated or improperly treated sewage is the major form of surface water contamination. Despite 67% of households in the country possessing septic systems only human sewage goes into the septic tank, with wastewater effluents from personal hygiene, cooking or washing clothes being discharged into natural streams without any further treatment (1). 57 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Natural streams are not the preferred source of domestic water supply due to potential water contamination, mostly from untreated sewage, sediment, and agricultural chemicals. Increasing episodes of water supply sources contamination by hydrocarbons, pathogens, gasoline, nitrates, herbicides (i.e. bromacil and diuron), and insecticide (i.e. terbufos) have been documented recently (1). Based on the high amount of microbiological contamination and the high incidence of waterborne diseases reported across the country, it is estimated that the amount of money spent on treating diarrheal disease in Costa Rica in 2002 was four times the potential cost of monitoring water and sanitation systems in the same period (1).

Panama Surface water in Panama is mainly represented by 150-350 rivers of mean length in the range between 56 and 350 km. However, the country has no water storage/control infrastructure. The national household coverage of drinking water and sanitation are 92.9% and 94.5%, respectively. However, there are communities with 50% or less of coverage of drinking water. From the total sanitation coverage, 33.1% of household are connected to sewage, 30% possess a septic tank, and 31.4% uses a latrine as the only sewage service (17).

Alternative Water Treatment and Sanitation Even though Central America precipitation and water resources may appear at glance to be a regional wealth of water, there are social, economic, legal, and political impediments to the efficient use and the protection of such abundant water resources. To supplying drinking water and sanitation, municipalities and operating agencies use expensive conventional water technology in spite of successful experiences in the region using low-cost technologies (8). The number of surface water sources reported as contaminated due to excess in agricultural practices has increased in Central America as a result of the massive use of herbicides, pesticides and fertilizers and untreated sewage. Fewtrell et al. (18) summarize the reduction in diarrheal disease morbidity due to improvements in one or more components of water and sanitation in less developed countries. Some of these interventions are point-of-use water treatment (hypochlorite chlorination, solar disinfection, boiling, pasteurization, and simple filtration), source improvements (safe household storage, tube well construction), sanitation (hand pump and latrine installation, pit latrine), and hygiene and health education. The reduction in diarrheal disease was 33% through improvement in hygiene, 36% related to sanitation, 19% associated with the improvement of water supply, and 12% related to multiple interventions. To improve drinking water and sanitation, local governments, NGO´s and citizens also should recognize the need to consider that the approach of centralized water treatment systems is as valuable as non-centralized water treatment systems when the necessary resources for implementation are available. 58 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


The approach of centralized water treatment systems is based on treatment plants with conventional treatment processes such as coagulation, flocculation, sedimentation, rapid or pressure sand filtration or, even ultrafiltration systems (19). It is well known that these treatment processes provide reasonably safe drinking water with few occurrences of coliform, and a very rare presence of E. coli, in the drinking water in zones that lack drinking water services (19). On the other hand, many communities in Central America do not have enough residents to warrant further development of centralized water treatment systems and the government will not invest in such systems for sparsely populated areas. For these cases, non-centralized water treatment systems have emerged in the last decade as an interesting cost-effective, on-site alternative for low-income, isolated rural, or peri-urban zones (20). Non-centralized water treatment systems are broadly divided in two categories described below: non-centralized drinking water systems and non-centralized sanitation systems.

Non-Centralized Drinking Water Systems In Central America, boiling water is one of the most common point-of-use water treatments for households. Even though the practice of boiling improves the microbiological quality of water, reducing thermo-tolerant coliforms by 86.2%, it does not fully remove the potential risk of waterborne pathogens. Furthermore, boiling water practices have the associated problems of requiring fuel and potential negative effect on indoor air quality (21). To avoid the potential limitations of water boiling procedures, other non-centralized drinking water treatment alternatives may be adopted such as filtration, solar disinfection, or chlorination. Among the most interesting non-centralized water treatment systems alternatives for Central America are: 1) Gravity-fed Ultrafiltration (GFU), 2) Solar Water Distillation, 3) Solar Water Disinfection, 4) Point-of-Entry/Use Chlorination, 5) Countertop UV Disinfection, and 6) Ceramic Filters for Point-of-Use. These systems are discussed in more detail in the following sections as proposed methodologies for the different areas in the region. 1) Gravity-fed Ultrafiltration (GFU). This system is useful for household applications, especially for low-income residents (22). It is a fully integrated, gravity-fed, point-of-use microbial water treatment system. To meet the needs of the most vulnerable populations, it was designed to operate without electricity or any other power input, and without a piped-in water supply. The process is designed to treat water of unknown microbiological quality and meet internationally recognized levels for microbiological water purifiers, as well as heavier levels of turbidity that may characterize water in such settings, especially during rainy seasons. The microbiological barrier consists of a 26-cm-long × 3-cm-wide plastic cylindrical cartridge containing some hollow fibers with a 20 nm pore size. Source water is introduced into the system by dipping the 2.5 L receptacle into an open vessel or pouring water into it whenit is hanging or mounted on a wall. The water passes through a cleanable 27-μm textile pre-filter mounted in the removal plastic 59 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


basket inside the receptacle, and then through a 1-m length of 12-mm diameter plastic tubing filling the cartridge. A slow-eluting solid chlorine tablet can be installed in the halogen chamber located at the receptacle to help prevent biofilm. When the side tap is opened, water passes through the walls of a hollow fiber membrane bundle that mechanically removes microbes and other suspended solids greater than 20 nm in size, as it flows out the tap,. The textile pre-filter is cleaned by removing its basket from the receptacle and rinsing it with water. The microbial cartridge (plastic tubing cartridge) must also be cleaned from time to time by backwashing it. Gravity-fed ultrafiltration is usually designed to produce ~150 mL of product water/minute (9 L/hour) and to last for at least 18,000 L. As it relies on mechanical filtration and not disinfection or adsorption, there is no need for a means of measuring volume of water treated or end of useful life; as long as the device remains intact, water from the tap will be effectively treated. When the flow from the unit cannot be restored to an acceptable rate by pre-filter cleaning and cartridge backwashing, the entire unit should be replaced, as intended. Assuming a household of five persons, the unit is capable of providing 2 L of safe drinking water per person per day for almost five years without any part replacement. In larger quantities, the manufacturer sells this configuration for about two dollars. Using the previous assumptions, this works out to less than $1 per person per year. The cost per liter of treated water would be $ 0.001. The device was tested through 20,000 L (~110% of design life) at moderate turbidity (15 NTU), achieving a 6.9 log reduction of E. coli, 4.7-log reduction for MS2 coliphage (proxy for enteric pathogenic viruses), and 3.6 log reduction for Cryptosporidium oocysts. This exceeded levels established for microbiological water purifiers. With periodic cleaning and backwashing, the GFU unit produced treated water at an average rate of 143 mL/min (8.6 L/hour) (range 293 to 80 mL/min) over the course of six months of evaluation (22). 2) Solar Water Distillation. Since the early 1990s, there has been a continuous effort to develop solar water distillation technology to meet drinking water requirements in poor water regions (24). It has been demonstrated that solar distillation effectively eliminates salts (i.e., arsenic), heavy metals, bacteria, and microbes from contaminated water sources as well as some pesticides and volatile organic compounds (23). It is also able to provide cost-effective, reliable, and safe water. A solar distiller uses the basic principles of evaporation and condensation for cleaning water. The contaminated feed water enters into the distiller, and the solar radiation penetrates a glass surface, causing the water to heat up through the greenhouse effect and subsequently evaporate. It has been determined that about 0.5 m2 of solar water distiller area is needed per person to meet their potable water needs consistently throughout the year (23). When the water evaporates inside the still, the purified water condenses on the underside of the glass, runs into a collection trough, and then to a collection container. During the process, the salts and microbes in the raw water remain in the original feed water and are left behind. The additional water fed into the still flushes out concentrated waste from the basin to avoid excessive salt build-up from the evaporated salts. Solar distilled water production rate is a function of the amount of solar energy and ambient temperature. Typical production efficiencies 60 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


for single-basin solar stills have been determined to be up to 60 percent in the summer and 50 percent during the colder winter, with typical production of about 0.8 liters per sun-hour per square meter. The effectiveness of distillation for producing safe drinking water is well established and long recognized (20, 24). Distillation is the only stand-alone point-of-use (POU) technology with NSF (National Sanitation Foundation) certification for arsenic removal. Solar distillation removes all salts and heavy metals, as well as biological contaminants (i.e. Cryptosporidium parvum, E. coli) (23). Although initially, lack of interest by the population for owning a solar distiller was reported, solar water distillation technology has gradually improved over the past decades. Over time, some households started to reconsider the idea of using alternative, clean energy to achieve their water requirements. In the survey carried out by Hanson et al. (23), a very important percentage of the population showed enthusiasm about the economic benefits of using solar distillation for safe drinking water production. They found that paying a relatively low price for a solar distiller was a favorable alternative to having to buy water on a regular basis. Others valued the independence and fascination they experienced from being involved in the production of their purified water. In many cases, residents were concerned about the color or odor of the local water supply, while the overwhelming characteristic that gains the residents’ attention is poor taste. Survey results showed that one of the reasons residents looked for a water purification system was to improve the taste of their local water. Since many of the local water supplies are high in salts and minerals (e.g., iron or sulfur), they often have a marginal or poor taste. 3) Solar Water Disinfection. Solar water disinfection (SODIS) is an environmentally friendly and low-cost point-of-use treatment technology for drinking water purification (25). SODIS takes advantage of the bacteriostatic capability of the UV-A portion (wavelength 320–400 nm) of solar radiation combined with the dissolved oxygen to inactivate pathogens in water through the production of reactive oxygen species (ROS). Typically, SODIS uses UV-A-transparent polyethylene terephthalate (PET) bottles filled to three-fourths of their capacity with water; agitated to increase the water’s dissolved oxygen content; and exposed to sunlight for six hours. According to the Swiss Federal Institute of Aquatic Science and Technology (26, 27), the best bacteria inactivation effect is reached when heat and UV radiation combine synergistically (28, 29). SODIS has been widely tested for application in rural communities in Mexico where water is scarce. Removal up to 100 percent of the pathogenic microorganisms in water has been achieved by direct exposure to solar radiation using plastic bottles of commercial beverages. The technological approach has been identified as cost-effective for application in marginal communities (25, 30). Different studies have been performed to determine energy requirements and doses to achieve pathogen inactivation to a certain level. Some of them have shown thermal inactivation of Escherichia coli is important only when water reaches temperatures over 45 °C when a strong synergy with the effect of radiation is observed. It is concluded that disinfection using solar energy is a low cost and effective method to improve the microbiological quality of water in places with high ambient temperatures and solar radiation (31). However, bacterial regrowth after short storage (24 hours) of SODIS-treated water has been observed (32, 33). 61 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Seeking improvements in SODIS performance, research has focused on a reduction in irradiation time. Prevention of bacterial regrowth and advanced oxidation processes (AOPs) have been found to be important contributors in SODIS enhancement. AOPs generate hydroxyl radicals (•OH) via titanium dioxide (TiO2) photocatalysis, Fenton reagent (ferrous iron and hydrogen peroxide), UV/hydrogen peroxide, UV/ozone, electron beam excitation, sonolysis, and gamma irradiation. Among various AOPs, photocatalytic processes have been found to be very attractive for the mineralization (conversion into carbon dioxide, water, and other mineral species) of aqueous pollutants and inactivation of pathogenic microorganisms (31, 34–36). Recently, Sharma et al. (37) demonstrated that ferrates based technologies are highly promising and environmentally friendly and exhibit high oxidation capacity of persistent organic pollutants, inactivation of viruses and bacteria, and removal by coagulation of heavy metals and arsenic. Application of these technologies to water disinfection using solar radiation, coined as Enhanced Photocatalytic Solar Disinfection (ENPHOSODIS), has allowed the efficient inactivation of highly resistant microorganisms (31, 38, 39). Several different improvements have been developed for ENPHOSODIS processes to achieve higher disinfection rates using shorter irradiation times, or using not only the UV part of the solar radiation but also taking advantage of the solar visible spectrum (34, 38). Other mechanical improvements have been attempted, such as the immobilization of the semiconductor photocatalyst (i.e., titanium dioxide) on inert and transparent solid matrixes to avoid the solids removals step after the water treatment (32, 40). All these technological improvements focused on the generation of safe drinking water are currently under review, and no experimental results are reported for its field application as point-of-use water treatment processes. However, laboratory-scale results have been good enough to generate high expectations related to the application of ENPHOSODIS-type methodologies to remove chemicals and biological contaminants from drinking water (31, 38). 4) Point-of-Entry/Use Chlorination. An important concern related to water quality is the possibility of microbial contamination during collection, transport, and storage. Therefore, chlorination at the point-of-use or point-of-entry could be a low-cost (less than $1 per day/person) way to purify water. However, chlorine is known to be ineffective against important pathogens such as Cryptosporidium parvum and Giardia lamblia and the potential formation of harmful disinfection byproducts in waters containing low organic content (31, 41). 5) Countertop UV Disinfection. UV disinfection uses wavelength radiation between 100 and 280 nm (UV) being highly germicidal. UV disinfection has shown satisfactory results in removing total coliform, E. coli, and an indicator virus, bacteriophage MS2. Also, it is known to be highly effective for Cryptosporidium and Giardia strains (31). However, this method is not practical for low income households as it requires access to and ability to pay for electricity. 6) Ceramic Filters for Point-of-Use. Filters are constructed with clay and sawdust collected from available materials near to the communities. In this processes, size exclusion and sorption are the main mechanisms for bacteria removal. It has been demonstrated that the reduction in total coliforms and E. coli 62 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

can be as high as 87% and 92%, respectively (42). These results suggest that this point-of-use technology can effectively improve water quality in the developing world. To improve performance of ceramic filters it has investigated the effect of percent sawdust and impregnation with silver nanoparticles to reduce the viable counts in the effluent (42). The strengths and weakness of centralized water supply and these non-centralized water treatment technologies are summarized in Table 2


Non-Centralized Sanitation Systems Given the developing political and economic environment of Central America, centralized sewage management systems are not a realistic solution in the short to medium term (43). Small communities or tourism-based businesses will require decentralized wastewater management systems (DWMS) or non-centralized sanitation systems. The advantage of non-centralized sanitation systems over centralized systems is that smaller units can often be designed, installed, operated, and maintained using local materials and labor, and often without any mechanization or power requirements. They can be effectively used for various point sources of wastewater, such as schools, housing blocks, and tourist facilities. The following two non-centralized sanitation processes may be adequate for implementation in Central American to improve the quality of the wastewater being discharged into natural streams. 1) Coco peat based biofilter. Coco peat forms a low-cost biofilter that treats the polluted discharges from septic tanks (43) in areas where coconut production is locally important (i.e. El Salvador). Coco peat filter technology is a proven cost-effective, sustainable alternative to other secondary wastewater treatment technologies, showing removal efficiency of 90% of organic matter, suspended solids, and pathogenic bacteria (44). 2) Constructed wetlands. Constructed wetlands are well suited to some rural and developing areas. It has been shown that vertical flow constructed wetlands using Chrysopogon zizanioides and Cymbopogon flexuosus are useful to reuse domestic greywater with removal efficiencies in the range of 98% for turbidity, 80% of total suspend solids, 79% of chemical oxygen demand, 87% biochemical oxygen demand, 71% nitrates, and 52% phosphates (45). To improve performance of a constructed wetland, hybrid wetland systems have been also investigated showing significant improvements in the removal of ammonia (52%), 54 % of nitrate, 78% of biochemical oxygen demand, and 56% of chemical oxygen demand for effluents with chemical oxygen demand loading as high as 690 g m-2 d-1 (46).

63 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

64


Table 2. Review of the Strengthens and Weakens of the Point of Use, Point of Entry Technologies Proposed for the Central American Region Technology

Main reported advantages

Main estimated disadvantages

Sites/areas to be implemented

Main challenges for implementing

Not always applicable for scattered populations, fails with the removal of non-conventional pollutants (i.e. pesticides, emerging) in water; requires highly specialized operation

Urban locations with medium to high economical incomes

Investment, operational and maintenance costs; proper operation and efficient prices establishment

Centralized water supply system Includes well known/ conventional water treatment processes; able to generate the required amount/quality of water; initial and operative costs well understood Non-centralized water treatment 1) GFU

Designed for household use especially with low income; no power inputs required; able to meet international standards for microbiological quality

No replacement cost reported; may need periodical major maintenance; no information on the minimum water quality required is available; field tests must be carried out to assess its performance

Small settlements with dispersed population; low-income settlements lacking access to basic services (i.e. electricity, piped water)

Can affect water taste or odor; may need continuous water feeding to generate the required amount of water; process efficiency may decay for water with high load of suspended or dissolved solids

2) Solar distillation

Widely tested in field work along the US-Mexico border; able to remove not only microorganisms but other organic and inorganic pollutants (i.e. heavy metals, VOCs); provides cost-effective safe water

Requires significant amount of solar radiation; depending on the design it may have considerably low efficiency

Reported as highly applicable to the US-Mexico border strip; small settlements with high amount of solar radiation

Initial unwillingness of people to use the technology; investment and maintenance cost may be high, depending on source water quality

In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Main reported advantages

Main estimated disadvantages

Sites/areas to be implemented

Main challenges for implementing

3) Solar disinfection

Highly cost-effective; widely tested in field work; many different approaches reported

Requires significant levels of solar UV radiation; microorganism re-growth may occur if nor properly applied; use of recommended PET bottles may produce cross-contamination

Point-of-use technology; it may be applied in both rural or urban communities; tested in field work for many different conditions

Initial unwillingness of people to use the technology; difficult to determine the end point of the process during cloudy days; health risks related to cross-contamination

4) Chlorination

Highly cost effective, relatively easy to monitor, field tested

Ineffective against certain pathogens, overdosage is common and may lead to taste and odor and disinfection byproducts

Small settlements with spread population; low-income settlements lacking access to basic services (i.e. electricity, piped water)

Storage and dosing of chlorine; in the case of large storage tanks, difficulty in climbing the tank to monitor chlorine residual and addition of chlorine

5) Countertop UV disinfection

Designed for household use, highly effective against a wide spectrum of microbial pathogens, easy to operate, no formation of known disinfection by-products (DBPs), field tested

Moderate to high cost, requires electricity, maintenance of the UV lamp required.

Urban or rural communities with access to electricity

Initial investment of the device, periodic cleaning of the UV lamp

6) Ceramic Filters for Point-of-Use

Percent reduction of total coliform bacteria of 87.11% and E. coli bacteria of 92.82%, as well as turbidity

Cost of equipment and energy to produce filters

Nicaragua, Guatemala, Peru, Vietnam, Cambodia, Ghana, Yemen, and Myanmar

Optimizing the filter composition and manufacture and use procedures

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Technology

In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Conclusions The available data for the Central America region shows an important lack of understanding of the volume, use and quality of surface and underground water. As an example, a survey developed in Guatemala suggests a significant misinformation about the causes of diarrhea. The survey suggested that people attribute diarrheic diseases to dirty food (28%), to dirty water (44%), to flies/insects (3%), to poor hygiene/environment (12.5%), cold weather (16%), and to carrying heavy items (3%) (42). Consequently, any water intervention projects in the region should be coupled with educational initiatives as well as considering an ethnographic point of view (47) and anthropological tools (48) to improve public acceptability for the adoption of new technologies. In the region, water problems are closely related to waterborne diseases, pollution, gender equality, and infrastructure. This situation often results in country Governments reacting to the effects of contaminated domestic water rather than preventing water contamination that is the root cause of the problems. It has been pointed out that local authorities spend more than four times the cost of monitoring water and sanitation systems for treating water-borne diseases. Judicious use of funds to implement low-cost non-centralized drinking and water sanitation systems could significantly improve diarrheal diseases and lower treatment costs. Non-centralized drinking and sanitation water systems should be considered for local water legislation. Feasible drinking water treatment alternatives such as Gravity-fed Ultrafiltration, Solar Water Distillation, Solar Water Disinfection, Ceramic Filters for Point-of-Use and sanitation alternatives such as Biofilter or Constructed wetlands could become valuable tools for the improvement of the quality of life for the region’s inhabitants. For monitoring implementation of human right to water in rural and peri-urban areas a regional methodology should be developed and standardized. Flores et al. (49) propose consideration of availability, accessibility, affordability, quality, participation and access to information, and non-discrimination. Trevett et al., (50) provided evidence that water quality deterioration occurs between the points of supply and consumption. Showing that safe household storage is also very important. Finally, Governmental efforts should be aimed to 1) hygiene and health education, 2) non-centralized drinking water and sanitation interventions, 3) standardization of measurements of implementation of human right, and 4) consider anthropological variables to improve adoption and appropriation of practices and technologies.

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Drinking Water and Sanitation in Central America - ACS Publications

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