Microalgae–bacteria aggregates: effect of the hydraulic retention time on the municipal wastewater treatment, biomass settleability and methane potential

BACKGROUND The use of microalgae–bacteria systems is particularly attractive for wastewater treatment, and the generated biomass can be further used for methane production. The aim of this study was to evaluate the influence of the hydraulic retention time (HRT) on the organic matter, nutrient removal, settling properties and the biochemical methane potential using a granular microalgae–bacteria system in a high rate algal pond. RESULTS The primary microorganisms present in the system were constituted by diatoms, green filamentous microalgae and bacteria. At 2 d of HRT the system showed the lowest performance while high chemical oxygen demand (COD) (>92%), ammonium (>85%) and phosphorus (up to 30%) removal was observed at 6 and 10 d of HRT. High settling velocities (up to 8 m h−1) were observed due to agglomerates and granules as dominant structures. The highest methane yield and production rates (348 mL CH4 g−1 VS and 56 mL CH4 g−1 VS d−1) were observed with the biomass obtained at 10 d of HRT. CONCLUSION Flocs and granules were the dominant structures in the system. High settling velocities and low effluent total suspended solids concentrations were obtained at higher HRT. An inverse relationship between HRT and the biochemical methane potential was observed. © 2016 Society of Chemical Industry

[1]  Cedric Laurent,et al.  Anaerobic digestion of microalgal bacterial flocs from a raceway pond treating aquaculture wastewater: need for a biorefinery. , 2015, Bioresource technology.

[2]  Kerstin Kuchta,et al.  Microalgae-bacteria flocs (MaB-Flocs) as a substrate for fermentative biogas production. , 2015, Bioresource technology.

[3]  P. García-Encina,et al.  A case study of a pilot high rate algal pond for the treatment of fish farm and domestic wastewaters , 2015 .

[4]  Cristina González-Fernández,et al.  Chlorella vulgaris vs cyanobacterial biomasses: Comparison in terms of biomass productivity and biogas yield , 2015 .

[5]  S. Khanal,et al.  Anaerobic digestion of lignocellulosic biomass: challenges and opportunities. , 2015, Bioresource technology.

[6]  H. Oh,et al.  Nutrient removal and biofuel production in high rate algal pond using real municipal wastewater. , 2014, Journal of microbiology and biotechnology.

[7]  Gopalakrishnan Kumar,et al.  A cost-effective strategy for the bio-prospecting of mixed microalgae with high carbohydrate content: diversity fluctuations in different growth media. , 2014, Bioresource technology.

[8]  N. Boon,et al.  Treatment of industrial wastewaters by microalgal bacterial flocs in sequencing batch reactors. , 2014, Bioresource technology.

[9]  N. Boon,et al.  Up-scaling aquaculture wastewater treatment by microalgal bacterial flocs: from lab reactors to an outdoor raceway pond. , 2014, Bioresource technology.

[10]  A. Avagyan.  Theory of Global Sustainable Development Based on Microalgae in Bio and Industrial Cycles, Management-Changing Decisions in Areas of Climate Change and Waste Management , 2013 .

[11]  M. Dudek,et al.  Algae biomass as an alternative substrate in biogas production technologies—Review , 2013 .

[12]  Rajinikanth Rajagopal,et al.  A critical review on inhibition of anaerobic digestion process by excess ammonia. , 2013, Bioresource technology.

[13]  B. Riaño,et al.  Treatment of agro-industrial wastewater using microalgae-bacteria consortium combined with anaerobic digestion of the produced biomass. , 2013, Bioresource technology.

[14]  R Muñoz,et al.  Biochemical methane potential of microalgae: influence of substrate to inoculum ratio, biomass concentration and pretreatment. , 2012, Bioresource technology.

[15]  N. Abdel-Raouf,et al.  Microalgae and wastewater treatment. , 2012, Saudi journal of biological sciences.

[16]  A. O’Sullivan,et al.  Effects of hydraulic and solids retention times on productivity and settleability of microbial (microalgal-bacterial) biomass grown on primary treated wastewater as a biofuel feedstock. , 2012, Water research.

[17]  A. Avagyan.  Water global recourse management through the use of microalgae addressed to sustainable development , 2011 .

[18]  R. Craggs,et al.  Algal production in wastewater treatment high rate algal ponds for potential biofuel use. , 2011, Water science and technology : a journal of the International Association on Water Pollution Research.

[19]  Yanyan Su,et al.  Municipal wastewater treatment and biomass accumulation with a wastewater-born and settleable algal-bacterial culture. , 2011, Water research.

[20]  Beatriz Molinuevo-Salces,et al.  Nitrogen transformations under different conditions in open ponds by means of microalgae-bacteria consortium treating pig slurry. , 2011, Bioresource technology.

[21]  Beatriz Molinuevo-Salces,et al.  Open and enclosed photobioreactors comparison in terms of organic matter utilization, biomass chemical profile and photosynthetic efficiency , 2010 .

[22]  O. Kruse,et al.  Microalgae as substrates for fermentative biogas production in a combined biorefinery concept. , 2010, Journal of biotechnology.

[23]  Yingkuan Wang,et al.  Cultivation of Green Algae Chlorella sp. in Different Wastewaters from Municipal Wastewater Treatment Plant , 2010, Applied biochemistry and biotechnology.

[24]  Raúl Muñoz,et al.  Long-term operation of high rate algal ponds for the bioremediation of piggery wastewaters at high loading rates. , 2009, Bioresource technology.

[25]  Olivier Bernard,et al.  Anaerobic digestion of microalgae as a necessary step to make microalgal biodiesel sustainable. , 2009, Biotechnology advances.

[26]  T. Lundquist,et al.  Algae Grown on Dairy and Municipal Wastewater for Simultaneous Nutrient Removal and Lipid Production for Biofuel Feedstock , 2009 .

[27]  U. Neis,et al.  Symbiotic algal bacterial wastewater treatment: effect of food to microorganism ratio and hydraulic retention time on the process performance. , 2007, Water science and technology : a journal of the International Association on Water Pollution Research.

[28]  P. Kroth,et al.  Localization of EPS components secreted by freshwater diatoms using differential staining with fluorophore-conjugated lectins and other fluorochromes , 2007 .

[29]  Benoit Guieysse,et al.  Algal-bacterial processes for the treatment of hazardous contaminants: a review. , 2006, Water research.

[30]  K. Cho,et al.  Settling characteristics of problem algae in the water treatment process. , 2006, Water science and technology : a journal of the International Association on Water Pollution Research.

[31]  U. Neis,et al.  Bioflocculent algal-bacterial biomass improves low-cost wastewater treatment. , 2005, Water science and technology : a journal of the International Association on Water Pollution Research.

[32]  M. Hondzo,et al.  The effect of small-scale fluid motion on the green alga Scenedesmus quadricauda , 1997, Hydrobiologia.

[33]  A. Alldredge,et al.  Potential for increased nutrient uptake by flocculating diatoms , 1989 .

[34]  D. Gunnison,et al.  Resistance and susceptibility of algae to decomposition by natural microbial communities , 1975 .

[35]  W. J. Dyer,et al.  A rapid method of total lipid extraction and purification. , 1959, Canadian journal of biochemistry and physiology.

[36]  F. Smith,et al.  COLORIMETRIC METHOD FOR DETER-MINATION OF SUGAR AND RELATED SUBSTANCE , 1956 .

[37]  O. H. Lowry,et al.  Protein measurement with the Folin phenol reagent. , 1951, The Journal of biological chemistry.