Algal biomass production and wastewater treatment in high rate algal ponds receiving disinfected effluent

• Published in: Environmental technology 2013-07, Vol.34 (13-14), p.1877-1885
• Main Authors: Santiago, Aníbal Fonseca, Calijuri, Maria Lucia, Assemany, Paula Peixoto, Calijuri, Maria do Carmo, Reis, Alberto José Delgado dos
• Format: Article
• Language: English
• Subjects: algae/bacteria systems; algal biomass production; Bacteria; Biomass; Bioreactors - microbiology; Chlorella - growth & development; Chlorella - metabolism; Chlorophyll - metabolism; Disinfection - methods; Effluents; high rate algal ponds; Hydrogen-Ion Concentration; Microorganisms; Oxygen; Phytoplankton - growth & development; Phytoplankton - metabolism; Productivity; ultraviolet disinfection; Ultraviolet Rays; Waste Disposal, Fluid - methods; Waste water; Waste Water - chemistry; Waste Water - microbiology; wastewater; Wastewater treatment
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2013.812670

Algal biomass production associated with wastewater is usually carried out in high rate algal ponds (HRAPs), which are concomitantly used in the treatment of such effluent. However, most types of wastewater have high levels of bacteria that can inhibit the growth of algal biomass by competing for space and nutrients. The objective of this study was to assess the influence of ultraviolet (UV) pre-disinfection on the performance of HRAPs used for wastewater treatment and algal biomass production. Two HRAPs were tested: one received effluent from an upflow anaerobic sludge blanket (UASB) reactor - HRAP - and the second received UASB effluent pre-disinfected by UV radiation - UV HRAP. Physical, chemical and microbiological parameters were monitored, as well as algal biomass productivity and daily pH and dissolved oxygen (DO) variation. The UV HRAP presented highest DO and pH values, as well as greater percentage of chlorophyll a in the biomass, which indicates greater algal biomass productivity. The average percentages of chlorophyll a found in the biomass obtained from the HRAP and the UV HRAP were 0.95±0.65% and 1.58±0.65%, respectively. However, total biomass productivity was greater in the HRAP (11.4 gVSS m −2  day −1 ) compared with the UV HRAP (9.3 gVSS m −2  day −1 ). Mean pH values were 7.7±0.7 in the HRAP and 8.1±1.0 in the UV HRAP, and mean values of DO percent saturation were 87±26% and 112±31% for the HRAP and the UV HRAP, respectively. Despite these differences, removal efficiencies of organic carbon, chemical oxygen demand, ammoniacal nitrogen and soluble phosphorus were statistically equal at the 5% significance level.