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The aerobic granular biomass technology was optimized for treating nitrate-polluted groundwater based on the biological denitrification processes in order to provide drinking water. Reactors inoculated with granular biomass were operated at progressively lower C/N rate using acetate and methanol to encourage heterotrophic denitrification, in order to meet the recommended requirements described by European Drinking Water Framework Directive. The granulation and long-term stability of granular biomass under low C/N were successful for all stages, demonstrated compactness of granules and absence of filamentous microorganisms. The nitrate removal was similar in methanol- and acetate-fed reactors, occurring in both cases nitrate removal ratios > 80%, and fact allows the selection of one of both depending groundwater polluted case. Also, feeding reactors with 2 C/N ratio showed nitrate removal values of ≥ 95%, treating highly polluted groundwater (100 mg·L−1). The microbial diversity was higher in the methanol-fed reactor with representative phylotypes as Flavobacterium, Cytophagaceae, NS9 marine group, while species richness was higher in the acetate-fed reactor, which was mainly represented by Flavobacteriumgenus. Statistical analyses revealed the higher resilience of bacterial population on granules fed with acetate, showing more resistance under drop C/N ratio. Oscillating pollution in groundwater during seasonal periods should be treated using acetate as carbon source for denitrification carried out by granular biomass, while stable pollution concentrations over time allow the use of methanol as a carbon source since the greater microbial diversity allows the elimination of other contaminants present in groundwater.

Aerobic granular sludge reactors usually operate in sequential batch mode, although this configuration limits the treatment of large volumes of wastewater, and they require a storage system. To implement this technology at full-scale, it would be necessary to design a simple and compact continuous-flow bioreactor able to treat larger volumes of wastewater. In this study, four aerobic granular sludge single-chamber continuous-flow reactors (R1, R2, R3 and R4) were designed and operated at the lab scale to evaluate and select a bioreactor configuration that achieves high organic matter removal performance while maintaining a stable granulation for long-term operation, promoting the washout of filamentous microorganisms. Results confirmed that the bioreactor including a lateral decanter (R1), was able to work in a steady state without loss of granular biomass and reached 95% of organic matter removal performance. Its granules had excellent compaction, with settling velocity values above 100 m·h−1. The R1 bioreactor also allowed rapid biomass adaptation and therefore a fast start-up (11 days). Results of this preliminary study at the lab scale suggested that the new and simple bioreactor design could be promising for its implementation at full scale. For that, future research is required to optimise the current model and to determine the most suitable operational parameters to treat domestic wastewater at full scale.

Aerobic Granular Biomass (AGB) technology is widely used for urban and industrial wastewater treatment, however, its application in groundwater remediation, is practically unknown. A mixture of carbendazim, simazine, and diuron were amended to the nitrate-polluted synthetic groundwater at increasing concentrations to validate the ability of technology to remove both kind of pollutants, pesticides and nitrate which are commonly found in the water resources. The nitrate removal was a success with values below 0.010 g·L-1. The increased concentration of pesticides in the influent did not distort the pattern observed for pesticide removal. Carbendazim was almost completely eliminated, followed by simazine elimination, while diuron showed adsorption-desorption patterns during experimentation. The addition of pesticides had a drastic effect on the basal community conducted by proliferation of Hyphomicrobiumand Dokdonella. The pesticide compounds had a negative effect on number of copies for fungal population, while archaeal population was unharmed, according to qPCR results. Denitrifying bacteria need 70 days as acclimatization period for achieving activity values as initial inoculum. The results obtained have shown for the first time the capacity of AGB system to treat groundwater polluted with nitrate and pesticide using low carbon load. Therefore, the results suggested the potential application of AGB technology for the purification of groundwater polluted with both nitrates and pesticides.

Next-generation sequencing and metatranscriptomic analysis were used to study the diversity and characterize the gene machinery in a cold bioreactor treating urban wastewater located near the Polar Artic Circle. The bacterial population was dominated by the family Comamonadaceae; archaeal population was highly represented by Methanococcalesclones while class Sacharomyceteswas the most abundant Fungi. Metatranscriptomic analysis demonstrated several cold adaptation mechanisms such as the expression of cold-shock protein (CspA),trigger factor (TF), antitermination protein NusA and polyribonucleoide nucleotidytransferase (PNP). Genes coding for transcriptional regulator WhiB and peptide deformylase (def), described as targets of novel antibiotics were detected as well as multidrug resistance proteins ( MdtC, MdtD) and genes encoding resistance to arsenicals (arsr) and cobalt-zinc-cadmium (czcc). Moreover, genes that encode UV radiation resistance ( uvrA) and expression of catalase and superoxide dismutase to protect against reactive oxygen species (ROS) were identified. Prokaryotic metabolism was mainly related to energy metabolism pathways, while eukaryote metabolism was related to protein metabolism. The most annotated reads belonged to viral particles, specifically RNA-1 polyprotein was the dominant which is involved in viral replication, suggesting wastewater may be an important reservoir of viruses in cold environments. Despite low-temperature, microbial community identified by massive parallel sequencing in the activated sludge demonstrated high diversity and evenness in comparison with others WWTPs. In addition, metatranscriptomics analysis revealed high functional diversity with mechanisms against cold-shock, as well as multidrug and heavy metals resistant genes, widely detected in WWTPs worldwide.

An aerobic granular biofilm process was operated in a sequential batch reactor for treating nitrate-pollute groundwater at 6 ºC, which was fed with a progressively reduced carbon concentration to understand the nitrate removal efficacy in cold regions by denitrifying microorganisms. The evaluation of the performance reflected a quick granulation promoted by hydraulic stress and a high organic loading rate (OLR). The granules were dense and compact and kept stable conformation until the end of operation, despite the low temperature. Nitrate removal in the stage with high OLR was close to 100%, while the stage with the lowest OLR reached efficiencies higher than 87% in steady-state, suppose a successful advantage against other biological processes for treating drinking water. The bacterial community in the mature granules were colonized by cold-adapted microorganisms such as Holophagaceae and CandidatusMicrothrix. Methanospirillumand Bathyarchaeotawere the most abundant archaeal phylotypes, which showed a more stable consortium and Nectriaceae and Trichosporonaceaewere the most dominant fungal phylotypes for all stages. The qPCR revealed that the crucial role was played by Fungiand Bacteria, while Archaealost abundance in granular biomass, despite extreme conditions. Aerobic granular sludge is a robust biological technology able to remove nitrate in oligotrophic waters bodies.

Biodiesel is an alternative energy source and could be a substitute for petroleum-based diesel fuel. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. Most of the sources, methods and apparatus to produce biodiesel are reviewed here. Some of the patents propose the use of oils and fats of animal or vegetal origin and other kind of sources. Many others focus on the methods for the production or oxidation stability of the biofuel in order to make its production economically competitive. Several apparatus comprising reactors and refineries are also presented. This review article summarizes recent and important patents relating to the production of biodiesel to make its production a viable alternative.

The production of pantothenic acid and thiamine by Azotobacter vinelandii was studied in a chemically defined medium and a dialysed soil medium amended with different amounts of carbohydrate and NHinf4sup+. Pantothenic acid and thiamine were produced in large amounts in the culture medium containing 2.0–5.0% glucose and 0.1–0.3% NH4Cl. The results showed that the liberation of these vitamins was increased under adiazotrophic conditions and with an excess of C source.

A pilot-scale anammox biofilter was set up and operated using reject water in order to investigate its nitrogen removal performance and the microbial community present at different stages of operation of this technology. A novel material “Filtralite” was used a support in order to achieve shorter start-up periods and obtain higher nitrogen load removal than other anammox technologies. Physico-chemical analysis demonstrated that nitrogen removal efficiency was higher than 70% from operational Day 100, reaching steady-stable total nitrogen removal and NH4+-N of 82% and 91%, respectively, this results suggest the robustness and adaptability of the technology to withstand changing nitrogen loads in the influent. Molecular analysis showed the presence of Nitrosomonasand CandidatusBrocadiales with relative abundance on different key days at around 2.5% of total relative abundance, although other phylotypes involved in the nitrogen cycle were also found. RT-PCR analysis showed that the pre-seed Filtralite used promoted the occurrence of anammox bacteria and other ammonia-oxidizing bacteria. The eukaryotic community oscillated greatly during operation and did not show any clear pattern. Both Prokarya and Eukarya showed high diversity and evenness, attributes which were very stable during operation. The biofilter performed robustly, despite changes in influent and nitrogen load, validating its suitability for treating industrial or urban effluent with high nitrogen loading in order to avoid damages in the environment in the save-cost way.