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BACKGROUND: Microalgae biotechnology is considered as a promising way to recover nutrients from centrate wastewater for value‐added biomass production, but it is rarely adopted in a real‐world application. Current study confirmed that carbon deficiency and suspended solids are two problems jeopardizing the microalgae‐based wastewater remediation. In this regard, glycerol was added into centrate wastewater as exogenous carbon source and algal–bacterial cooperation for nutrients recovery assessment. RESULTS: The results showed that glycerol addition increased the biomass yield of algae from 1.54 to 2.58 g L⁻¹ in 5‐day culture and, at the same time, improved the removal efficiency of nitrogen and phosphorus, which were further assessed by pilot‐scale experiments. Bacterial community analysis indicated that algal–bacterial cooperation involves carbon dioxide and oxygen exchange, phosphorus absorption, and solid organics degradation, forming a complementary nexus beneficial for wastewater treatment. CONCLUSION: Glycerol is proven to be a good carbon source for microalgae growth in the centrate wastewater. Additionally, the cooperation between microalgae and bacteria plays a key role in the nutrients removal during centrate wastewater. It is expected the technology and knowledge provided by current work can further promote the industrialization of microalgae‐based wastewater remediation. © 2020 Society of Chemical Industry

With the continuous development of the livestock breeding industry, the amount of piggery wastewater discharged increases year by year, and the pressure of controlling environmental pollution continuously increases. A novel method using a co-culture of Chlorella pyrenoidosa and Rhodotorula glutinis in piggery wastewater was proposed in this study, which was aimed at treating piggery wastewater and producing useful products. The results showed that the optimal inoculum ratio of algae to yeast was 3 : 1 in the wastewater, which achieved the removal efficiencies of 58.53%, 36.07%, 33.20% and 56.25% for ammoniacal nitrogen (NH3-N), total nitrogen (TN), total protein (TP) and chemical oxygen demand (COD), respectively, after 6 d. The synergistic relationship of C. pyrenoidosa and R. glutinis was preliminarily validated using the oxygen/carbon dioxide exchange balance and scanning electron microscopy images. The co-cultivation system gained 59.8% (w/w) protein within 5 d which can be used as a feed additive, and produces aquatic animals with better growth and quality. Thus, the 1000 litre pilot scale bioreactor was used indoors and removed 82.65% of TN, 53.51% of TP, 93.48% of NH3-N and 85.44% of COD in 21 d which gave a better performance for TN (p < 0.05) than the bench scale results. This system improves the nutrition removal and protein production efficiencies, and is a promising method for piggery wastewater treatment and the pig breeding industry.

The high concentrations of ions and ammonia nitrogen (NH3−N) in soil washing wastewater can remarkably affect ecosystem balance. This study aims to prove the feasibility of using alkaline soil washing wastewater as inlet water of microbial electrolysis desalination and chemical-production cell (MEDCC) to desalinate and recover NH3-N, from the views of performance and mechanism. The system could obtain desalination, and NH3-N removal efficiencies of 73 ± 7% and 85 ± 3%, respectively, within 12 h at the maximum current density of 9.8 ± 0.1 A/m2. Importantly, 82.5% of the removed NH3-N could be recovered in the form of NH3·H2O. The addition of electrochemically active bacteria in the anode chamber of MEDCC improved desalination and NH3-N recovery efficiencies by strengthing electric field. Bioenergy provided 58% of the total energy consumption, forming an energy-saving method for soil washing wastewater treatment. Alkalization pretreatment and acid immersion could reduce precipitation from membranes to improve desalination performance and reduce energy consumption. From the standpoint of the mechanism of desalination and NH3-N recovery, the MEDCC is expected to have the potential to simultaneously complete desalination and NH3-N recovery in alkaline wastewater with low energy consumption.

The deposal of residual hydrogen peroxide (H2O2) in Fenton-like system and the requirement of oxygen in bioreactor are essential parts for the treatment of integrative Fenton-like/bioreactor. A novel low-cost integrative Fenton-like and MnO2-filled upward flow biological filter bed (Fenton-like/MBFB) equipped with the modified ceramsite was constructed to evaluate the main properties and catalytic activity of modified ceramsite, and the optimal conditions of integrative system and compare integrative and traditional systems. In this study, the Fenton-like reactor with modified ceramsite had higher catalytic ability whose Acid Orange 7 (AO7) degradation efficiency reached to 79.3% due to large surface area and high porosity, compared with that with raw ceramsite (44.3%). Furthermore, total utilization efficiency of H2O2 in integrative system (from 32.41% to 53.51%) and removal efficiencies of COD and AO7 were remarkably improved, which would effectively decrease the waste of H2O2 and the setting of regulation pool and aeration tank. Thus, the integrative system can save 0.51 CNY/m3 in construction cost and 0.21 CNY/m3 in operating cost. The average COD removal efficiency, AO7 degradation efficiency and effluent DO concentration were achieved to 64.8%, 79.5% and 9.3 mg/L respectively in integrative system were achieved in integrative system during sixty successive runs. Also, the potential degradation pathway of contaminants was also proposed according to the OH-enhanced at Fenton-like reactor due to catalyst and adsorption of modified ceramsite and the removal of microorganisms and modified ceramsite for contaminants at MBFB. This study demonstrated the feasibility of integrative Fenton-like/MBFB filled with modified ceramsite for simultaneously decreasing operational cost and complexity and enhancing removal efficiency, thus provided a one-step alternative for refractory dye wastewater.

Glycerol is important to algal growth, but it is not necessarily right for all wastewater-borne bacteria, especially the beneficial bacterial flora or beneficial bacterium. This study focuses on the microalgal-bacterial community and interactive network analysis between algae and wastewater-borne bacteria to find beneficial bacteria, then identify the effect of glycerol on a beneficial bacterial strain. Microalgal-bacterial remediation shown better nutrients removal and microalgal biomass in centrate wastewater, and glycerol addition considerably increased biomass but inapparently increase nutrients removal. Pseudomonas sp. and Acinetobacter sp. dominated in algal-bacterial system with and without glycerol. Microbial community and environmental factors formed a linkage network in three cultural modes to find the most vital probiotic. The co-cultivation of microalgae and Pseudomonas aeruginosa as a non-fermentative denitrifying phosphate accumulating organism (DPAO) showed co-cultivation dramatically enhanced biomass yield and nutrients removal efficiencies, especially nitrogen and phosphorous. After adding glycerol, in the late stage of co-cultivation, algal-bacterial consortia collapsed, rendering the reduction of treatment efficiency and biomass. Non-fermentative bacteria as main probiotics in algal-based wastewater remediation were required to prepare small-molecule-weight organics as carbon sources. This study expects to optimize design and operation of algal-bacterial wastewater remediation that can be extended to similar carbon-deficit wastewaters simultaneously obtaining higher biomass and removal efficiency.

Aiming at simplifying the harvesting procedure, reducing the production cost, and improving the quality of microalgae-based biodiesel, herein, a novel one-step method for oil-rich biomass production and harvesting was proposed by growing Chlorella sp. with Aspergillus sp. in molasses wastewater. Lipid content and fatty acid profile were measured to assess the suitability of microalgal-fungal biomass for biodiesel production. The results showed that the highest biomass yield (4.215 g/L) was obtained when the inoculation ratio of fungi and microalgae was 100. Activities of fungi positive impacted the decolorization of wastewater and the removal of suspended solids. Thus, co-cultivation system had better performance than mono-system of microalgae in the removal of nutrients in wastewater. Analysis of biomass compositions showed that compared with mono-system of microalgae, co-cultivation system produced biomass with higher lipid content (35.2%) and yield microbial cell oil with lower unsaturation degree, potentially increasing the quality of microbial-cell-lipid based biodiesel.