Operation of Vacuum Sewer System - case Ondangwa, Namibia
Mäkinen, Marika (2016)
Mäkinen, Marika
2016
Ympäristö- ja energiatekniikan koulutusohjelma
Luonnontieteiden tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2016-06-08
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201605254074
https://urn.fi/URN:NBN:fi:tty-201605254074
Tiivistelmä
The purpose of this thesis was to analyze the malfunctioning vacuum sewer system in Ondangwa, Namibia. The system did not form adequate vacuum to transport sewage from the formation place to the vacuum station and therefore the collection chambers were flooding. The aim was to find the failures that caused malfunctioning, causes of the failures and solutions for the failures. In addition, four other vacuum sewer systems in Namibia were studied for comparison purposes. They were located in Gobabis, Henties Bay, Kalkrand and Stampriet. A two month field trip was done in Namibia in October and November 2014 and three methods were used to analyze the vacuum sewer systems in Namibia. The methods were literature survey, semi-structured interview and observation.
The vacuum sewer system in Ondangwa has faced many failures since the beginning of the design phase in 2006 until November 2014. The failures have been related to the vacuum pumps, vacuum sewers and collection chambers. There had been issues also during the design and construction phases. Majority of the failures have been caused by external factors (vandalism, misuse of the system and poor maintenance). However, the system is also difficult to maintain in the local conditions and material defect of the vacuum sewer system has also caused failures: the valve controllers break down easily when they are in touch with moisture. The impacts of the failures have exposed users and operators of the system to health risks and environment to contamination due to the sewage on the streets. The failures and the causes of the failures in the other vacuum sewer systems in Namibia have been very similar with the system in Ondangwa. Thesystem in Henties Bay had the least amount of failures and the vacuum sewer system in Ondangwa had the biggest amount of failures. In November 2014 the system in Ondangwa did not operate anymore due to broken vacuum pumps.
Ondangwa and the four other LA’s of Namibia have two options. They should either invest a lot on the improvement of the vacuum sewer systems or replace them with more applicable sewer systems. For example gravity sewer system is more familiar technology to the sewer system operators and users in Namibia. However, the improvement of the maintenance and protection of the system and education of the users is essential with gravity, vacuum or any other system. Otherwise vandalism and inadequate maintenance will cause failures also in the future, no matter what system is operating. The vacuum sewer system operation can be improved by fixing all the failures with proper materials and by proper contractors. The findings of this thesis are useful for improving the poor sanitation situation in Ondangwa and in the four other LA’s.
The vacuum sewer system in Ondangwa has faced many failures since the beginning of the design phase in 2006 until November 2014. The failures have been related to the vacuum pumps, vacuum sewers and collection chambers. There had been issues also during the design and construction phases. Majority of the failures have been caused by external factors (vandalism, misuse of the system and poor maintenance). However, the system is also difficult to maintain in the local conditions and material defect of the vacuum sewer system has also caused failures: the valve controllers break down easily when they are in touch with moisture. The impacts of the failures have exposed users and operators of the system to health risks and environment to contamination due to the sewage on the streets. The failures and the causes of the failures in the other vacuum sewer systems in Namibia have been very similar with the system in Ondangwa. Thesystem in Henties Bay had the least amount of failures and the vacuum sewer system in Ondangwa had the biggest amount of failures. In November 2014 the system in Ondangwa did not operate anymore due to broken vacuum pumps.
Ondangwa and the four other LA’s of Namibia have two options. They should either invest a lot on the improvement of the vacuum sewer systems or replace them with more applicable sewer systems. For example gravity sewer system is more familiar technology to the sewer system operators and users in Namibia. However, the improvement of the maintenance and protection of the system and education of the users is essential with gravity, vacuum or any other system. Otherwise vandalism and inadequate maintenance will cause failures also in the future, no matter what system is operating. The vacuum sewer system operation can be improved by fixing all the failures with proper materials and by proper contractors. The findings of this thesis are useful for improving the poor sanitation situation in Ondangwa and in the four other LA’s.