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Municipal Wastewater Treatment Using Microalgal-Sludge System

Amini, Elham | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47090 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shaygan Salek, Jalaloddin; Mehrnia, Mohammad Reza
  7. Abstract:
  8. If wastewater is not properly treated, then the environment and human health can be negatively impacted. These impacts can include harm to fish and wildlife populations, oxygen depletion and contamination of drinking water. In the typical wastewater treatment process, the goal of primary, secondary and tertiary effluent treatment is to reduce or remove organic matter, solids, nutrients, disease-causing organisms and other pollutants from the treated wastewater before it is discharged to a body of water. Biological methods for wastewater treatment are much preferable for being more economical and environmentally friendly. Biological treatment of wastewater using algal-bacterial culture biotechnology has received considerable attention in the last decade. In the algal-bacterial treatment under illuminated conditions, algae produce O2 by photosynthesis, which is required by the bacteria to mineralize organic matter. This should overcome most of limitations of the conventional biodegradation methods based on mechanical aeration. In this study, semi- continuous algal–bacterial systems, composed of green microalgae, chlorella vulgaris and activated sludge, were cultivated to treat municipal wastewater and accumulate biomass simultaneously. The influence of algae and sludge inoculation ratios on the treatment efficiency were investigated. There was no significant effect of the inoculation ratios on the chemical oxygen demand (COD) removal. Comparatively, the nutrients removal and related mechanisms were varied with different inoculation ratios. The highest N-NH4+ and P-PO43- removal efficiencies were observed with 5:1 (algae/sludge) culture (94% and 80%, respectively). 72%, 60%, 52% and 30% P-PO43- was removed at the 21st day of the experiment in the reactors inoculated with algae/activated sludge ratio of 1:1, 1:5, only algae and only sludge respectively. The removal efficiencies of NH4+ at the 21st day of the experiment was 81%, 65%, 71% and 30.75 in the reactors inoculated with algae/activated sludge ratio of 1:1, 1:5, only algae and only sludge respectively
  9. Keywords:
  10. Microalgae ; Activated Sludge ; Municipal Wastewater Treatment ; Microalgae-bacterial Culture ; Algae/Activated Sludge Inoculum Ratio

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