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Performance of a small wastewater stabilisation pond system in tropical climate in Dar es Salaam, Tanzania
KTH, Superseded Departments, Biotechnology.
KTH, Superseded Departments, Biotechnology.
2003 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 11-12, 187-191 p.Article in journal (Refereed) Published
Abstract [en]

Waste stabilisation ponds (WSP) are widely used in Tanzania. Their traditional design focuses on BOD and pathogen removal, but nutrient removal is equally important. WSP performance was evaluated to come up with information that would be used to evaluate pond performance. Samples were analysed twice a month for six months. Results showed total and faecal coliform removal by 4 log units (99.96 and 99.98% respectively). There was partial reduction of COD, BOD, (46% and 27% respectively), conductivity and total dissolved solids (32.6 and 32.4% respectively). Variation for the nutrients like inorganic phosphorus, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen was not consistent and there was practically no reduction, although there is some nitrification taking place. From this study it may be concluded that BOD and nutrients may not be useful to evaluate pond performance. Instead parameters such as conductivity, total dissolved solids, coliform bacteria, dissolved oxygen, pH and chlorophyll would be suitable for that purpose, due to their consistent variation within cells of the pond system. But BOD and nutrient removal are important and have to be improved to enhance treatment in the WSP.

Place, publisher, year, edition, pages
2003. Vol. 48, no 11-12, 187-191 p.
Keyword [en]
waste stabilisation pond performance, water quality index, removal, experiences, design
National Category
Industrial Biotechnology
Identifiers
URN: urn:nbn:se:kth:diva-23092ISI: 000188094900025Scopus ID: 2-s2.0-0346639198OAI: oai:DiVA.org:kth-23092DiVA: diva2:341790
Conference
5th International Conference on Small Water and Wastewater Treatment Systems, Istanbul, 2002
Note

QC 20100525

Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2014-12-15Bibliographically approved
In thesis
1. Microbial Phosphorus Removal in Waste Stabilisation Pond Wastewater Treatment Systems
Open this publication in new window or tab >>Microbial Phosphorus Removal in Waste Stabilisation Pond Wastewater Treatment Systems
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Waste Stabilisation Ponds (WSPs) are characterised by low phosphorus (P) removal capacity. Heterotrophic bacteria are principal microbial agents in WSPs in addition to algae. As treatment proceeds in WSPs, algal growth increases and pH rises, this has lead to believe that P removal is mainly through sedimentation as organic P algal biomass and precipitation as inorganic P. In activated sludge treatment plants (AS), microbial P removal has been improved and is termed as enhanced biological phosphorus removal. There was a need to establish whether it was possible to enhance P removal in WSPs. A performance assessment of pond system at the University of Dare s Salaam (UDSM), Tanzania, has shown that 90% of the P removed was in the primary pond (facultative) and the rest in the maturation pond (aerobic).

In these studies, a pure strain A. hydrophyla was isolated from an activated sludge wastewater treatment plant in Sweden. This plant has a train that functions with enhanced biological phosphorus removal. The strain was tested for P uptake in minimal media supplemented with glucose, succinate or acetate, grown aerobically and anaerobically/aerobically. This strain was able to take up P without having been subjected to the anaerobic phase. It was observed that P uptake was enhanced after the anaerobic phase with media supplemented with glucose, but not with succinate or acetate. Phosphorus uptake repeatedly followed the bacterial growth pattern with correlation coefficients of more than 95%. Therefore P removal has a direct correlation with bacterial growth.

Two isolates Acinetobacter sp. (isolated from the primary facultative pond) and E .coli (isolated from the maturation pond) were obtained from a tropical WSP treatment system at the UDSM. They were subjected to aerobic P uptake experiment similar to those of A.hydrophyla. The uptake per unit absorbance of bacterial growth was found to be comparable to that of A.hydrophyla, isolated from AS. These results showed that heterotrophic activity is important in WSPs. It is possible to enhance P removal in these systems by designing the primary ponds for maximum heterotrophic activity and probably enrichment.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. iv, 35 p.
Keyword
Wastewater treatment, waste stabilisation ponds, activated sludge, biological phosphorus removal, tropical climate, A.hydrophylla
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-3876 (URN)91-7178-280-X (ISBN)
Presentation
2006-03-10, Sal FA32, AlbaNova, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101119Available from: 2006-03-03 Created: 2006-03-03 Last updated: 2010-11-19Bibliographically approved

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