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Wastewater treatment in ponds, Brazil
2000 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The major purpose with this study was to make a comparison between to different ways of treating wastewater: aeration and chemical precipitation. The fullscale study was made in a small town called São Joao da Boa Vista, Brazil. To determine the chemical sort and chemical dose, we used jar test. As a preparation for the fieldstudy in Brazil, we put together data from different fellingsdams in Sweden. The comparison was based on the parameters: TSS, organic matter (COD), economy and other parameters as smell and colour. From the results in the jar test, we decided to add 70 mg/L of FeCl3. The results showed a 56% removal efficiency of TSS and COD using aeration. Chemical precipitation gave a 58% removal efficiency of COD and a 27% removal efficiency of TSS. The major operational problem during the aerated stage was foam formation due to a high content of phosphorus in the wastewater. When chemical precipitation was used Fe-sulphides were formed, which gave the wastewater a black colour. The Fe-sulphides formed because of the anaerobic conditions in the lagoons. The Fe-sulphide formation will lead to that the required dose of chlorine will increase greatly to reach a satisfactory disinfection of the effluent wastewater. From the results we made the following recommendations: To improve the chemical precipitation we suggest adding a twice as high chemical dose and lowering the pH of the wastewater. To avoid the problem with Fe-sulphide formation, alum should be further studied. Short-circuiting may occur in the ponds therefore, make a comparison between the real detention time in the ponds and the theoretical detention time.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Wastewater, Chemical precipitation, Aeration, Fellingsdams, Stabilisationponds, Brazil
Keyword [sv]
URN: urn:nbn:se:ltu:diva-51833ISRN: LTU-EX--00/242--SELocal ID: 9038b06b-bdf9-4469-a2f0-b6598bdce753OAI: diva2:1025197
Subject / course
Student thesis, at least 30 credits
Educational program
Environmental Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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