Epsilon Archive for Student Projects

Abstract

The access to good sanitary facilities is an important factor that elevates the experienced living standard as it improves hygiene and reduces the transmission of deseases. The ratification of the millennium goals by 189 countries demonstrates that this is an important international issue. Together the countries have taken upon themselves that the proportion of the population that lacked access to sustainable safe drinking water and sanitary facilities in the year 2000 will have been reduced by half by the year 2015.

In Peru, the construction of sewage pipe networks to transport the sewage out of the direct human environment is progressing. The safety and sustainability of these systems can be questioned, since in Peru the sewage seldom receive any treatment before being emitted to a recipient. This is taking place in Picota and sorrunding villages as well.

In the last 25 years several systems implementing small-scale onsite treatment have been introduced throughout Latin America in an attempt to give more people access to sustainable and safe sanitary facilities, reducing water consumption and taking advantage of the agricultural values of the sewage fractions while protecting the environment from its negative impact.

In this study three different sanitary systems and the effects of different population growths were compared. The systems consisted of artificial wetlands, pond systems and small-scale onsite treatment. These were also compared to the construction of a smaller wastewater treatment plant in combination with small-scale onsite treatment for different system sizes.

The fluctuation in the water level of the river complicates the construction and operation of a wastewater treatment plant. A plant submitted to seasonal flooding invariably needs to be protected by dikes. Even though protected by dikes the river water entering the sewage system when the water level rises will render the sewage plant unoperational up to six months every year.

In the city of Picota the introduction of small.scale onsite treatment would cut the investment cost by over one third compared to the construction of an artificial pond system for a population of 7500 persons. The costs of the investment in an amplified sewage system and the economical benefits from the reuse of the waste products in ecological sanitation were not included in these calculations.

The use of dry urine-diverting toilets signifies a considerable saving in the form of reduced water consumption. Its implications are both of economical and practical importance. A reduction in consumption per capita would mean that the water produced today could satisfy the need of more people without using more resources. In this manner the introduction of ecological sanitation also helps reaching the millennium goal of reducing the proportion of people lacking sustainable access to safe drinking water.

Another aspect of small-scale onsite treatment is that it is independent of the size of the system. The future development of the population does not have to be taken under consideration when implementing the system, thus avoiding big investments in large permanent infrastructure. This makes it more flexible and leaves more possibilities open for the future.

A system based on onsite treatment offers greater protection against transmission of deseases and higher protection for the environment than a wastewater treatment plant. It also offers greater possibilities for involving the community in the process of decision-making and implementation of the system. This can help to promote the interaction and communication between the authorities and the population, thereby strengthening the democracy.

Tillgången till fullgoda sanitära faciliteter höjer levnadsstandarden betydligt. Boendemiljön förbättras vilket leder till bättre hygien och mindre smittspridning. Att detta står högt på den internationella agendan visar FN:s milleniummål som fastställts av 189 länder. Tillsammans har länderna åtagit sig att fram till år 2015 halvera andelen människor utan tillgång till säkert dricksvatten och sanitet jämfört med år 2000.
I Peru byggs avloppsnätet ut för att avlägsna avloppet från människans närmaste boendemiljö. Uthålligheten och säkerheten hos denna lösning kan ifrågasättas då den sällan kompletteras med behandling av det producerade avloppsvattnet. Utbyggnad av avloppsnätet sker även i Picota och omgivande byar.
I Latinamerika har allt fler system med lokalt omhändertagande av avloppet införts de senaste 25 åren i ett försök att minska vattenkonsumtionen, erbjuda fler människor en uthållig och säker sanitet samt att utnyttja resurserna i avloppsfraktionerna samtidigt som utsläppen och den negativa miljöpåverkan minimeras.
I studien jämfördes tre olika avloppssystem: artificiella våtmarker, biodammar och lokalt omhändertagande. Inverkan på ekonomi och hållbarheten hos mindre reningsanläggningar i kombination med lokalt omhändertagande vid olika systemstorlekar undersöktes också.