Microalgae population dynamics growth with AnMBR effluent: effect of light and phosphorus concentration

Enhanced nutrient removal and bioenergy production in microalgal photobioreactor following anaerobic membrane bioreactor for decarbonized wastewater treatment

This study investigated the nutrient removal, decarbonization potentials, and bioenergy production (i.e., algal biomass and biogas) between a membrane photobioreactor (MPBR) and a sequencing photobioreactor (SPBR) as the post-treatment process of an anaerobic membrane bioreactor (AnMBR) for municipal wastewater treatment. All photobioreactors without aeration showed favourable performance on AnMBR effluent polishing and bioenergy production. In comparison, MPBRs achieved higher removal efficiencies with 98.4 %-99.1 % NH4-N and 74.8 %-88.4 % PO4-P removal compared to the SPBRs with 41.1 %-82.0 % NH4-N and 39.6 %-72.9 % PO4-P removal. MPBRs enhanced more nutrient utilization (24.9-49.3 g(N)/(m3·d) and 3.4-8.1 g(P)/(m3·d)) and CO2 assimilation (22.9-43.4 g(C)/(m3·d)), and concentrated more microalgae with 1.58-1.98 g/L higher than the SPBRs. Moreover, the MPBR effectively upgraded the biogas from AnMBR with superior methane percentage of 89.4 %-93.4 % due to its better CO2 biofixation. The MPBR, with better carbon, nitrogen and phosphorous removal and bioenergy production, following AnMBR is an attractive decarbonized technology for future sustainable wastewater treatment.

Membrane processes

This literature review provides a review for publications in 2018 and 2019 and includes information membrane processes findings for municipal and industrial applications. This review is a subsection of the annual Water Environment Federation literature review for Treatment Systems section. The following topics are covered in this literature review: industrial wastewater and membrane. Bioreactor (MBR) configuration, membrane fouling, design, reuse, nutrient removal, operation, anaerobic membrane systems, microconstituents removal, membrane technology advances, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include the following: Biological Fixed-Film Systems, Activated Sludge, and Other Aerobic Suspended Culture Processes, Anaerobic Processes, and Water Reclamation and Reuse. This publication might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants.

Optimising an outdoor membrane photobioreactor for tertiary sewage treatment

The operation of an outdoor membrane photobioreactor plant which treated the effluent of an anaerobic membrane bioreactor was optimised. Biomass retention times of 4.5, 6, and 9 days were tested. At a biomass retention time of 4.5 days, maximum nitrogen recovery rate:light irradiance ratios, photosynthetic efficiencies and carbon biofixations of 51.7 ± 14.3 mg N·mol^-1, 4.4 ± 1.6% and 0.50 ± 0.05 kg CO₂·m³_influent, respectively, were attained. Minimum membrane fouling rates were achieved when operating at the shortest biomass retention time because of the lower solid concentration and the negligible amount of cyanobacteria and protozoa. Hydraulic retention times of 3.5, 2, and 1.5 days were tested at the optimum biomass retention times of 4.5 days under non-nutrient limited conditions, showing no significant differences in the nutrient recovery rates, photosynthetic efficiencies and membrane fouling rates. However, nitrogen recovery rate:light irradiance ratios and photosynthetic efficiency significantly decreased when hydraulic retention time was further shortened to 1 day, probably due to a rise in the substrate turbidity which reduced the light availability in the culture. Optimal carbon biofixations and theoretical energy recoveries from the biomass were obtained at hydraulic retention time of 3.5 days, which accounted for 0.55 ± 0.05 kg CO₂·m^-3_influent and 0.443 ± 0.103 kWh·m^-3_influent, respectively.

Evaluation of the population dynamics of microalgae isolated from the state of Chiapas, Mexico with respect to the nutritional quality of water

As Chiapas state, México, counts on an extensive hydrography with diverse nutrimental and climatic characteristics, it therefore allows isolating and identifying microalgae with bioenergetics potential.

For this purpose, samples from 8 locations were collected, corresponding to 6 rivers, a wastewater and a springwater. The isolation of microalgae was developed for 4 weeks with 12:12 light/dark cycles. We demonstrated that the most efficient means for the isolation of microalgae of the hydrographic areas evaluated was the medium BG11 with 80.53% effectiveness. Of the microalgal consortium identified, 90% are composed of microalgae belonging to the class Chlorophycear. It was shown that another factor favouring the richness of morphotypes identified in the Santo Domingo River is associated with adequate concentrations of macroelements such as nitrates, nitrites, ammonium, phosphorus, sodium, potassium, magnesium and calcium at concentrations of 0.03 mg/l, 0.0006 mg/l, 0.08 mg/l, 0.03 mg/l, 62.93 mg/l, 5.46 mg/l, 34.52 mg/l and 48.78 mg/l respectively and microelements such as copper, zinc, iron, andmanganese at concentrations less than 0.2 mg/l in all microelements. The identified morphotypes, according to literature, have lipid contents ranging from 2 to 90%; this is of biotechnological importance for the production of biodiesel.