Search

Conventional biological treatment usually cannot achieve the same high water quality as advanced treatment when conducted under varied temperatures. Here, satisfactory wastewater treatment efficiency was observed in a microalgae-bacteria consortia (MBC) over a wide temperature range because of the predominance of microalgae. Microalgae contributed more toward wastewater treatment at low temperature because of the unsatisfactory performance of the accompanying bacteria, which experienced cold stress (e.g., bacterial abundance below 3000 sequences) and executed defensive strategies (e.g., enrichment of cold-shock proteins). A low abundance of

Antibiotics abuse has triggered a growing environmental problem, posing a major threat to both ecosystem and human health. Unfortunately, there are still several shortcomings to current antibiotics removal technologies. Microalgae-bacteria consortia have been shown to be a promising antibiotics treatment technology owing to advantages of high antibiotics removal efficiency, low operational cost, and carbon emission reduction. This review aims to introduce the removal mechanisms, influencing factors, and future research perspectives for using microalgae-bacteria consortia to remove antibiotics. The interaction mechanisms between microalgae and bacteria are comprehensively revealed, and their exclusive advantages have been summarized in a "Trilogy" strategy, including "reinforced physical contact", "upgraded substance utilization along with antibiotics degradation", and "robust biological regulation". What's more, the relationship between different interaction mechanisms is emphatically analyzed. The important influencing factors, including concentration and classes of antibiotics, environmental conditions, and operational parameters, of antibiotics removal were also assessed. Three innovative treatment systems (microalgae-bacteria fuel cells (MBFCs), microalgae-bacteria membrane photobioreactors (MB-MPBRs), and microalgae-bacteria granular sludge (MBGS)) along with three advanced techniques (metabolic engineering, machine learning, and molecular docking and dynamics) are then introduced. In addition, concrete implementing schemes of the above advanced techniques are also provided. Finally, the current challenges and future research directions in using microalgae-bacteria consortia to remove antibiotics have been summarized. Overall, this review addresses the current state of microalgae-bacteria consortia for antibiotics treatment and provides corresponding recommendations for enhancing antibiotics removal efficiency.

Biochar (BC) adsorption has been widely acknowledged as an efficient approach for the removal of antibiotics. Despite the importance of oxygen-containing functional groups for the antibiotics removal, most of these may be obtained in BC only relying on the addition of oxidants. Herein, an environmentally friendly and oxygen-enriched functional groups adsorbent, namely Chlamydomonas BC (CBC), was fabricated via simple pyrolysis process. Then, the H-bonding, electron donor-acceptor and electrostatic attraction were identified as the main mechanisms regarding sulfathiazole (STZ) adsorption (506.38 mg/g). The carbon-oxygen functional groups on the surface of CBC (61%), especially -COOH and -OH, acted as a pivotal component. Additionally, further theoretical calculation led to the observation that STZ exhibited the highest chemical reactivity (η = 0.04), strong electron exchange capacity (μ = -0.16), remarkable electron accepting capacity (ω = 0.28) and excellent electron transfer efficiency (E

We developed and demonstrated a novel intimately coupled photocatalysis and biodegradation (ICPB) system. The ICPB system was comprised of photocatalytic optical hollow-fibers (POHFs) coated with Ag-loaded GeO2 and N-doped TiO2 photocatalyst, along with a biofilm that included phototrophic and heterotrophic microorganisms. The POHFs exhibit high UV–visible photocatalytic activity to degrade phenolic compounds rapidly and stably, decrease toxicity, generate readily biodegradable products, and emit visible light for biofilm growth and O2 production by phototrophs. O2 produced by the phototrophs was transferred to the POHFs, helping generate hydroxyl free radicals for photocatalysis. The biofilm, which became enriched in Rhodococcus and Pseudomonas, maintained rapid and stable biodegradation of photocatalytic products from the phenolics. Thus, the synergism among photocatalysis, biodegradation, and photosynthesis in the novel ICPB system provided an efficient means to rapidly and sustainably degraded and mineralized high concentrations of phenolic compounds.

Microalgae biodiesel is a candidate to provide renewable, C-neutral energy. However, microalgal cells possess strong cell walls and cell membranes with high selective permeability, both of which hinder the extraction of lipids from the microalgae. Optimizing lipid extraction involves disrupting the microalgae’s cell wall and membrane. The hydroxyl free radical (•OH) can attack the cell wall and cell membrane in the microalgae, making the microalgae more susceptible to lipid extraction. Introduced here is a PhotoElectroChemical (PEC) with TiO2-based photoanode utilized UV–Vis light to produce •OH at a phosphate-palladium cathode. Until now, PEC has not been utilized to disrupt microalgal cells to improve the extraction of microalgae lipids. Here, a novel PEC system -- comprised of two nitrogen-doped TiO2 nanotube photoanodes, a bipolar membrane, and a phosphorus-palladium cathode -- was demonstrated to disrupt microalgal biomass to improve lipid extraction. PEC utilizes ultraviolet and visible light as the only input energy for the effective disruption of the microalgal cell. Pretreatment of Chlorella using the PEC system resulted in 96% oil-extraction efficiency which was approximately 10 times higher than that achieved without the pretreatment and an increases in desirable C16:0. Also explored were the mechanisms underlying •OH generation and microalgae disruption. PEC promises to be an eco-friendly and low-energy technology that can promote the development of microalgae industries.

Chromite ore processing residue (COPR) is a kind of hazardous industrial solid waste produced in the chromium salt industry that needs to be disposed of properly and safely. In this work, an agricultural waste of citrus peel (CP) was used to detoxify COPR by the pyrolysis process, and the resulted residue (DT-COPR) was used as the adsorbent to treat simulated nickel ion (Ni2+) wastewater. The effects of pyrolysis parameters on the COPR detoxification efficiency and adsorption performance of Ni2+ were investigated simultaneously. Besides, operating parameters on the adsorption efficiency and capacity of Ni2+ were also studied and the adsorption kinetics and equilibrium isotherms were summarized correspondingly. The results show not only water-soluble but also insoluble (Cr(Ⅵ)) in the COPR can be effectively reduced by the pyrolysis process, and the total Cr(Ⅵ) decreased from 1641.98 mg/kg to 8.04 mg/kg that can be used safely as an adsorbent. The characterization results of DT-COPR also show that the new adsorbent exhibits good thermal stability and full of chemical functional groups, and adsorption equilibrium of nearly up to 100% of Ni2+ removal efficiency with DT-COPR was achieved within 10–60 min. The adsorption process of Ni2+ can be accurately described by the pseudo-second-order model and Langmuir isotherm, and the theoretical maximum adsorption capacity (qmax) for Ni2+ could reach as high as 18.18 mg/g. This study provided an alternative treatment of bio-safety disposal and resource-oriented utilization of the COPR.

Understanding kinetics of microalgae growth in landfill leachate are essential to operate landfill leachate remediation with microalgae in the most efficient manner possible. In the study, kinetics of microalgae Chlorella vulgaris growth, nutrients uptake and metabolism in response to major influencing factors were investigated. Energy potential of microalgae in landfill leachate was assessed to provide guide for large-scale application. Results showed that the highest maximum specific growth rate of 2.31 d−1 was obtained under low light intensity of 60 μmol/m2/s (dilution rate = 10%, CO2 concentration = 5%), while the highest maximum biomass concentration of 1.64 g/L was obtained under light intensity of 160 μmol/m2/s (dilution rate = 10%, CO2 concentration = 7%). The specific uptake kinetics of nutrients by microalgae presented obvious difference between various species and obvious luxury uptake of N O 3 − was observed. Metabolism flow of intracellular compositions under various operating conditions were quantitatively depicted. Energy yield analysis indicated that the highest volumetric energy yield (37.13 kJ/L) was comparative to the volumetric heat value of natural gas (35.59 kJ/L).

Phycoremediation of landfill leachate (LL) with microalgae is a promising approach but the performances are usually inhibited by complex macromolecular organics and high chromaticity of the LL. To realize high-efficiency LL remediation and microalgae biomass production, a technique integrating ozonization and microalgae bioremediation was proposed, in which the LL was first pretreated with ozone to degrade most macromolecular organics and reduce chromaticity. Then the oxidized LL was remediated with microalgae biofilm to reclaim nutrients and produce biomass. Results showed that chromaticity was sharply reduced from 1400 to 45 Pt–Co and macromolecular organics were significantly reduced from 93.3% in the untreated LL to 54.8% in the oxidized LL via ozonization under 45 mg O3/L for 45 min. The oxidized LL effectively enhanced microalgae growth and nitrogen removal. Then a phosphorus-feeding strategy was adopted to obtain different nitrogen/phosphorus (N/P) molar ratio of 33:1, 16:1; 7:1 and 3:1 for further enhancement of microalgae growth and nitrogen removal. As results, the maximum biofilm density of 28.0 g/m2 and the highest nitrogen removal efficiency of 81.6% under N/P molar ratio of 16:1 were achieved.