Water Treatment in the Cities in Nicaragua
4. Water Treatment in the Cities in Nicaragua
Due to the concentration of the population in urban areas, which has reached 58% of the total population in Nicaragua, there is a high demand for water for human consumption and consequently, considerable volumes of wastewater is discharged as a product of daily activities.
4.1 Waste Water Treatment Coverage in Nicaragua’s Urban Zones
According to the report presented by ENACAL for 2010, the potable water coverage increased from 72% to 84%, but the sanitary sewer coverage still is lagging behind. However, an increase from 33%
to 39% was achieved from 2007 to 2010. Likewise, wastewater treatment increased by 200% in 2010 in relation to the existing coverage in 2007 (ENACAL, 2010). It is important to point out that ENACAL provides its services mainly to the country’s urban centers. This implies that the figures that were presented are for urban areas.
Currently, there is no official data about wastewater treatment coverage but the country has new treatment units that include the Waste Water Treatment Plant (PTAS in Spanish) for the city of Managua. This is the largest work in the water and sanitation sector in the Central American region and was installed in 2009. The plant has a treatment capacity of 180 cubic meters per second; however official data indicates that the plant is currently treating 66.6 million cubic meters per year. Parallel to the installation of the plant, 121,000 sewage system users were connected in the city of Managua (ENACAL, 2010). The project is part of the Lake Xolotlán sanitation program, where wastewater has been discharged since 1927. It intends to recover this resource for recreation without contact and to promote sanitation in the city of Managua (Figure 4.1).
The government has made efforts to rehabilitate the wastewater treatment plants in the cities of León, Chinandega, Rivas, Nagarote, Granada, and El Viejo. Likewise, repairs are planned for another 25 treatment plants throughout the country (ENACAL, 2010).
4.2 Treatment Coverage According to Economic Level
Speaking of wastewater treatment coverage in Nicaragua is difficult since the belief is that the wastewater that receives treatment comes from the sanitary sewage drainage system whose coverage in the urban areas is just 39% (ENACAL, 2010). In addition to this scenario, it is important to note that not all the sewage systems discharge their wastewater into a treatment plant and not all the wastewater treatment plants treat 100% of the water that they receive.
In Managua, the whole urban center of the old downtown (prior to the 1972 earthquake) and the new downtown Managua, including populated neighborhoods located in the peri-urban zones whose
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existence dates back to prior to the 80s, has a sanitary Figure 4.1 Modern Wastewater Treatment Plant for the sewer system. This is not true for the spontaneous
City of Managua
settlements that peaked in the decades of 80s and 90s. The settlements were a product of internal migration within the country where the rural population migrated to urban areas as a result of the war in the 80s, famines, and extreme events such as droughts and flooding and the presence of hurricanes. The proliferation of these human settlements without any urban utilities has meant that many so far do not have any sanitary sewer systems.
The government, through ENACAL, has made efforts to solve this problem. The construction project for the wastewater treatment plant in Managua increased the sanitary sewer system coverage in some of the human settlements in the capital. Also, in the Condominium Sanitary Sewer Implementation Project, an innovative system will
be installed. The system consists of a network of connections as horizontal property within each block that are connected with collective pipelines through an inspection box (ENACAL, 2009). The
4.3 Treatment of Gray Water
system consists of public collectors, treatment units. The benefits of this system include the low cost
Currently, the installed capacity to treat municipal and easy construction of residential connections, a
wastewater consists of 32 plants throughout the greater number of connections, the use of smaller
country including: Lagoon systems, Imhoff tanks diameter pipes, and participation by the population
followed by Upflow Anaerobic Biological Filter, in the project. The settlements that have this type of
Imhoff tanks followed by bio-filtering, septic system are: Arnoldo Alemán, Lomas de Guadalupe,
tanks followed by Upflow Anaerobic filters an Maria Dolores Alemán, Israel Galeano, Comandante
Upflow Anaerobic Sludge Blanket (UASB) system Aureliano, Nueva Sabana, Villa Reconciliación Norte,
and a modern system (the Managua Treatment Carlos Núñez, Georgiano Andrade, Laureles Norte,
Plant) made up of physical and biological removal Parrales Vallejos, and Pedro Aráuz Palacios. The processes, which consists of primary settling tanks, project will serve more than 120,000 inhabitants in
drip filtering, and secondary settling tanks. It is
27 neighborhoods in the capital with an investment important to point out that more than 55% of the of 320 million cordobas financed with funds from
treatment plants existing in Nicaragua are lagoon the World Bank and the Reconciliation Government
systems; however this policy has changed due to and National Unity (ENACAL, 2009).
budget restrictions and availability of suitable areas But these new middle and upper class urban
for building lagoon systems (ENACAL, 2009). developments in the capital, which are mostly
In Nicaragua, municipal wastewater that flows located outside the perimeter of the Managua urban
through sanitary sewers is made up of gray water, area, are unable to connect their sanitary drains
black water, and in the rainy season, rainwater from to the city’s sanitary sewer system. Consequently,
some domains that have connected their rainwater they have their own wastewater treatment systems
drainage to the system illegally. This situation brings in the form of individual septic tanks or collective
consequences for the composition of the domestic sanitary sewer and wastewater treatment systems
wastewater and means a higher organic load, a of their own. They consist of compact plants or
high concentration of nutrients such as nitrates packages pertaining to systems with activated and phosphorus, abundant presence of pathogenic sludge, Imhoff Tanks, etc.
groups, sediments, and detritus (IANAS, 2012).
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Most of the treatment systems implemented in
4.5 Returning Water to the Environment
the country under optimal operating conditions turn
out to be efficient in removing the organic load and suspended solids but this is not the case for the re-
The effluents from the treated water from wastewater moval of nutrients and pathogens. However, most of
treatment plants in the country are mostly returned the domestic wastewater treatment systems in the
to surface waterbodies. For example, the effluent country are in a state of advanced deterioration due
wastewater from the wastewater treatment plant to lack of maintenance (Figures 4.2 a and b), poor op-
in Managua is released into Lake Xolotlán through erations, and not adecuate dimensioning of capacity
a submerged emitter located at a distance of 1½km for necessary load and treatment.(IANAS, 2012).
from the coast. The effluents from the treatment plants in Granada and San Juan del Sur are discharged
4.4 Reuse (Successes and Problems)
through runoff into Lake Cocibolca. The effluents from the treatment plant in Masaya are discharged
Currently, no data is available about the volume or directly into Lake Masaya, etc. (ENACAL, 2010). For portion of treated water that is reused. This portion
example, returning the treated water to Lake Masaya may be minimal due to the fact that generally final
(Figures 4.2a and b) has resulted in the deterioration disposal of treated effluents is into surface waters
of the lake’s water, causing anoxia in 80% of the such as lakes and rivers.
water column (CIRA/UNAN, ENACAL, 2013). Using treated water in the country is not a
The effluents from residential developments are common practice. This might be due to the fact
disposed of through infiltration wells. This becomes that wastewater treatment systems in the country
a latent risk of contamination for the groundwater have turned out to be not very efficient in removing
resources and many of them are located in the pathogens, which does not facilitate their reuse recharge area in the watershed south of Managua (ENACAL, 2009).
Figure 4.2 State of Maintenance of the Oxidation Lagoon in the City of Masaya
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Returning the treated water to the environment, Table 5.1 Classification of Diseases Originating in Water to aquatic ecosystems, is very feasible if the water
were not a threat and an environmental tensor for
Cholera, typhoid fever,
the receiving waterbodies. However, in practice,
Human or animal
this is not the case, due to the high deficiency of
treatment, to the point that the treated water from
Living creatures who live
these plants mostly holds large quantities of groups caused by nematodes,
part of their life cycle in
trematodes, and cestodes.
of pathogens, high concentrations of nitrogen,
phosphorus, and detergent, and a considerable Malaria, dengue, yellow
Vector-born diseases related
Related to vectors that
develop in water
organic load, etc. This becomes a threat from the
Related to a
Shortage of fresh water
limnological and sanitary point of view.
and deterioration of
Trachoma, ring worm, lice,
sanitary condition of the