Decentralized sanitation systems for the southern Ecuadorian Andes assessment and challenges

ntua.gr/ reported in Ecuador and several developing countries, the public investments in infrastructure for collection and treatment of domestic wastewater in the rural and peri-urban areas have increased regularly during the last decades. However,the majority of the decentralized systems located in those areas are still working under low efficiencies and facing several Operational and Maintenance(O&M) difficulties in comparison to urban areas and conventional systems (Nanninga et al., 2012). In Ecuador, three main reasons stand behind this behavior: i) the population dynamics and the illicit discharges into the collection systems which often change rapidly and significantly
the design fluxes to the systems; ii) the inadequate or inexistent management and maintenance of the systems neither by the authorities nor by the direct users of the systems; and iii) the
technological aspects and the failures in the design process. “Yet how many municipal engineers know what all the sanitations options are, how to choose between them and how to design the chosen option?” (Mara,2013). The vast amount of resources invested in sanitation in the rural areas with relative low success, have motivated the analysis of the state-of-the
-art of the decentralized systems in several countries, through an exhaustive bibliographic
review of academic reports, scientific articles, interviews and current information of national and international entities, focusing in the technological options and good practices with comparable environmental and socio-economic characteristics to the rural and peri
-urban communities of Ecuador, with a particular emphasis in the southern Andean region.

Environmental Sanitation of the Ecuadorian rural sector Ecuador accounts the highest population density among the South America countries. From its 15 million of inhabitants, the rural population represents the 37%. In the rural area, only the 23% of house holds are connected to a public sewerage system (INEC, 2014). The 30% are connected to a septic tank (ST) or a
secondary treatment, and around 28% of houses are served by other minor
improved sanitation facilities. As seen, the 19% of households in the rural sector (around 250000 houses) do not have any sanitation infrastructure (INEC, 2014). There is no information about the number of WWT systems that are functioning in the rural sector of Ecuador
. However, in the whole country,currently only two of the big cities (Quito and Cuenca), have full scale Wastewater Treatment (WWT) systems already built or under construction.
The Ecuadorian Andes cover a wide range of environmental conditions, which vary from snow peaks to humid subtropical. For the analysis presented in this manuscript, the sout
hern Andean region of Ecuador with moderate rainfall and temperatures from 12 to 24 °C is selected.

Ecuador has some government agencies in charge of the environmental sanitation at different levels.
These include the National Secretariat of Planning and Development (SENPLADES), Information
Systems for Autonomous Governments (SIGAD), the National Water Secretariat (SENAGUA) and the Decentralized Local Governments (GADs). In the last years, the progress in sanitation coverage
has been evident both in the urban and rural areas of the country. Ecuador met the Millennium Development Goal (MDG) for basic sanitation in 2014 (WHO/UNICEF, 2015)
. However, for the treatment of domestic effluents, there is an important gap especially in the O&M of the DWWT located in the rural areas. Despite of the important efforts of the different agencies, an effective connection between the actions of these agencies and the organizational and management competences of the communities served is still needed. The environmental and health education in the rural areas should be reinforced in the institutional agendas. In addition, the engineers in the public institutions must have the competences for chose the most suitable option for a particular place and to design properly the systems together to an O&M plan. In rural areas of the southern Andean region of Ecuador, there are, unfortunately many examples of DWWT systems that have completely lost their functional
ity due to the lack of O&M. This can be associated directly with intermittent or no involvement of the served population and the scarcity of resources of the public agencies. Decentralized management does not mean inefficiency or abandon and is independent of socioeconomic level of the population. Fam et al. (2014) and Viet Anh et al.(2004) reports good examples of well-organized communities in Melbourne (Australia) and Hanoi(Vietnam) respectively which were supported by volunteers and education workshops about the benefits of the wastewater treatment and the saving of water resources. Meleg (2012), instead,presents a similar study in three low -income communities in Brazil. Here, the Integrated Rural Sanitation System (SISAR) model was established. The SISAR model comprises a community organization in small clusters with a cross-subsidy scheme. Thus, the income of big systems, compensates the costs of O&M of small systems, providing also support in technical, social and administrative matters. The success of SISAR model was built on the integration and responsibility. of all the inhabitants of
a particular area, improving the overall quality of life.

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CONCLUSIONS AND RECOMMENDATIONS
The decentralized systems offer a smart and sustainable solution for DWWT in rural and peri-urban
areas in the southeast Andean region of Ecuador. The technological offer of DWWT is wide and in
constant development around the world; however, there is a preference towards the anaerobic systems mainly because of the low O&M costs. The temperature is undoubtedly a determinant factor when considering the technical feasibility of the systems; nevertheless,
even at low temperatures , the anaerobic processes in combination with aerobic or anaerobic systems could be an efficient alternative to remove DBO and pathogenic organisms. Considering the
environmental conditions of the Andean subtropical regions analyzed, the anaerobic systems are
a convenient technological alternative, particularly in individual septic tank units or in
more advanced units such as UASB reactors. A combination of septic tanks followed by an anaerobic filter or constructed wetlands are also good alternatives for DBO and
pathogen removal. On the other hand, at the mountain region with lower temperatures, there are still various viable alternatives; among them, the anaerobic filters followed by a hybrid anaerobic reactor; or, a combination of a UASB reactor or a septic tank with an anaerobic filter. Nevertheless, it is also feasible to improve the environmental sustainability of these systems including sludge dehydration and disinfection for reuse in so ilapplication.
However, these technological alternatives require a validation by pilot experiences under different environmental conditions before their implementation. In addition, it is necessary that the governmental organizations encourage that the design processes must consider sound characterizations of the effluents, and the analysis of the receive water bodies and their self-purification capacities. Furthermore, the actual organizational strength of the community served should be considered on beforehand for planning the O&M activities. The level of success of the decentralized system is directly proportional to the level of community involvement. In order to achieve the fundamental objective of any treatment system, it is strongly suggested to first convince the system users about
the necessity of domestic effluent treatment to preserve both the public health and the
environment. The community organizational capacities could be noticeably improved with the involvement of community leaders in the O&M responsibilities reinforcing at the same
time the environmental education, among children, teenagers and young adults. Consequently, it is crucial, to reinforce the administrative and organizational capacities of the
communities which could be extended to other productive local schemes. In Ecuador, finally, it is necessary to reinforce scientific research towards decentralized WWT technologies and to strengthen the capabilities of the engineers in the whole process
of technology selection, design, and operation and maintenance of decentralized DWWT systems. Read Article