Cultivation of green algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant

Liang Wang, Min Min, Yecong Li, Paul Chen, Yifeng Chen, Yuhuan Liu, Yingkuan Wang, Roger Ruan

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The objective of this study was to evaluate the growth of green algae Chlorella sp. on wastewaters sampled from four different points of the treatment process flow of a local municipal wastewater treatment plant (MWTP) and how well the algal growth removed nitrogen, phosphorus, chemical oxygen demand (COD), and metal ions from the wastewaters. The four wastewaters were wastewater before primary settling (#1 wastewater), wastewater after primary settling (#2 wastewater), wastewater after activated sludge tank (#3 wastewater), and centrate (#4 wastewater), which is the wastewater generated in sludge centrifuge. The average specific growth rates in the exponential period were 0.412, 0.429, 0.343, and 0.948 day-1 for wastewaters #1, #2, #3, and #4, respectively. The removal rates of NH4-N were 82.4%, 74.7%, and 78.3% for wastewaters #1, #2, and #4, respectively. For #3 wastewater, 62.5% of NO3-N, the major inorganic nitrogen form, was removed with 6.3-fold of NO2-N generated. From wastewaters #1, #2, and #4, 83.2%, 90.6%, and 85.6% phosphorus and 50.9%, 56.5%, and 83.0% COD were removed, respectively. Only 4.7% was removed in #3 wastewater and the COD in #3 wastewater increased slightly after algal growth, probably due to the excretion of small photosynthetic organic molecules by algae. Metal ions, especially Al, Ca, Fe, Mg, and Mn in centrate, were found to be removed very efficiently. The results of this study suggest that growing algae in nutrient-rich centrate offers a new option of applying algal process in MWTP to manage the nutrient load for the aeration tank to which the centrate is returned, serving the dual roles of nutrient reduction and valuable biofuel feedstock production.

Original languageEnglish (US)
Pages (from-to)1174-1186
Number of pages13
JournalApplied Biochemistry and Biotechnology
Issue number4
StatePublished - Oct 2010

Bibliographical note

Funding Information:
Acknowledgement The authors are grateful to Robert C. Polta in Saint Paul Metropolitan Council Environmental Services (MCES) for helping in the sample collection. The study was supported in part by grants from the Legislative-Citizen Commission on Minnesota Resources, MCES, University of Minnesota Initiative for Renewable Energy and the Environment, and the Center for Biorefining.


  • Algae
  • Centrate
  • Chlorella
  • Metal
  • Municipal wastewater
  • Nutrients removal


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