The emerging accumulation of microplastics (MPs) in global waters is of increasing concern and it is posing great health risks to both humans and aquatic species, yet suitable technologies to remove MPs are lacking. The objective of this study was to investigate activated sludge as a source of promising biocatalysts for the removal of MPs in water. Bacterial communities in activated sludge were first screened for their potential to degrade hydrolyzable plastics from polyethylene terephthalate (PET) pre-treated at 100 C for 1 hour. The consortium grew on a mineral medium with PET MPs as the sole carbon and energy source. To further assess its degrading potential, the consortium was put through a standardized CO 2 evolution test at a temperature of 30 C, pH 7-7.5, reactor residence time 168 days, and PET concentration of 2.63 g/L. The biodegradation extent was further validated through assessment of morphological/structural changes on the PET by means of SEM, DSC, FTIR, and viscometry analyses. Upon incubation, the consortium degraded 17% of PET. The molecular weight remained unchanged, reflecting a degradation via surface erosion. Furthermore, the biodegradation was significantly enhanced at high oxygen flow rates. Two bacterial strains within the consortium were isolated and identified as Bacillus cereus SEHD031MH and Agromyces mediolanus PNP3. Both strains thrived when individually cultured with PET while only B. cereus showed enzymatic activity during a clear-zone test. The examined bacterial strains possess a promising PET-degrading activity that can be further investigated and applied to the elimination of MPs water/wastewater through innovative and effective technologies.
Simultaneous nitrification and denitrifying phosphorus removal was achieved in a single-sludge continuous flow bioreactor. The upright bioreactor was aligned with a biomass fermenter (BF) and operated continuously for over 350 days. This study revealed that unknown bacteria of the Saprospiraceae class may have been responsible for the successful nutrient removal in this bioreactor. The successive anoxic-aerobic stages of the bioreactor with upright alignment along with a 60 L BF created a unique ecosystem for the growth of nitrifier, denitrifiers, phosphorus accumulating organisms and denitrifying phosphorus accumulating organisms. Furthermore, total nitrogen to chemical oxygen demand (COD) ratio and total phosphorus to COD ratio of 0.6 and 0.034, respectively, confirmed the comparative advantages of this advanced nutrient removal process relative to both sequencing batch reactors and activated sludge processes. The process yielded 95% nitrogen removal and over 90% phosphorus removal efficiencies.
Eutrophication is reported as the most important water quality issue around the world. The potential death of Lake Winnipeg, the world's ninth largest lake, is a dramatic exampe of this ecological disater in Canda. Property price devaluation, tourist repulsion, and toxicity due to eutrophication cause the annual economic losses over $3 billion in Europe, South and North America. The objective of this thesis is to develop an efficient biological nutrient removal reactor to be commercialized and used in the water/wastewater treatment industry. This bioreactor has a unique configuration which is filed as a US patent technology called "Compact Upright Bioreactor for the Elimination of Nutrients", invented by M. Alvarez Cuenca and M. Reza. It consists of four stages including Deaeration, Anoxic, Anaerobic and Aerobic where Do removal, denitrification and phosphorus removal processes take place respectively. The bioreactor performs very well obtaining 100% Do removal and 98% nitrate removal efficiency. The phosphorus removal process requires much longer operational period to reach steady state. The phosphorus removal process shows variable results having a maximum of 60% removal success.
The excess of nutrients like nitrogen and phosphorous compounds in surface water (ie, coastal areas, lakes, and rivers) is responsible for major economic, public health, and environmental crises. Their impact is measured in multi‐billion‐dollar losses, in greenhouse gas emissions and severe algal blooms whose toxicity and geographical dimensions are being monitored and recorded. The present paper focuses on four areas, namely: (a) the economic impact of nutrient pollution, (b) a brief glance at the evolution of the technologies associated with nutrient removal from water/wastewater, (c) a review of the existing conventional planar reactors used in nutrient removal plants, and (d) a description of a novel multi‐stage vertical bioreactor and its removal performance, microbial ecology, comparative costs, and construction flexibility. This bioreactor with acronym STAR (simultaneous treatment for ammonia/phosphate removal) is the first multistage bioreactor with vertical configuration used for the simultaneous nitrification, denitrification, and biological phosphorus removal from wastewater. The bioreactor shows high nutrient removal efficiencies of over 95% for both phosphorous and nitrogen compounds. Due to its vertical configuration, this bioreactor requires a smaller footprint and its modularity makes it exceedingly flexible to accommodate to the restricted construction spaces in urban areas.
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