Enhanced phosphorus removal from wastewater by growing deep-sea bacterium combined with basic oxygen furnace slag

The potential utilization of slag generated from iron- and steelmaking industries: a review

Along with iron and steel production, large amount of slag is generated. Proper management on the iron- and steelmaking slag is highly demanded due to the high cost of direct disposal of the slag to landfill, which is the most adopted management approach. In this article, the potential application of iron- and steelmaking slag has been reviewed, which included the slag utilization in construction as cement and sand, in water, soil, and gas treatment, as well as in value material recovery. In addition, the challenge and required effort to be made in iron- and steelmaking slag management have been discussed.

Performance evaluation of modified bioretention systems with alkaline solid wastes for enhanced nutrient removal from stormwater runoff

Bioretention systems have been found to be potential candidates for the removal of various pollutants/nutrients from rainfall or stormwater runoff. Despite bioretention has been widely developed for the removal of nutrients from stormwater, effective removal of both phosphorus and nitrogen is still a challenge. Hence, in this study, bioretention systems modified by alkaline solid waste media have been reported for the effective removal of nutrients. Six different types of solid wastes were first assessed using leaching and adsorption tests, and then the bottom ash from a refuse incineration plant was selected as a modifier. The bottom ash was mixed with soil to form a special media as the filter layer in the bioretention systems. The nutrient removal efficiencies of the modified bioretention systems were evaluated and also compared with those of the unmodified control. For this purpose, the design of the modified filter media with a saturated zone was combined to enhance the simultaneous removal of nitrogen and phosphorus. The effect of different rainfall intensities and nutrient concentrations in stormwater runoff on the removal efficiency of nutrients was evaluated. The results indicated that the modified bioretention with bottom ash modified soil media and saturated zone could exhibit the excellent removal efficiency of nitrogen and phosphorus from stormwater runoff. The extent of removal of total nitrogen, total Kjeldahl nitrogen, and total phosphorus was found to be 58-70%, 66-82% and 82-97%, respectively. The performed correlation analysis showed that the bioretention cell using the special media could simultaneously enhance the removal of phosphorus and nitrogen. As a part of this study, the adsorption isotherms of phosphorus removal by the modified bioretention systems have also been determined. Finally, the implications and opportunities for deploying modified bioretention systems for optimizing water-energy nexus and stormwater management were illustrated. In overall, this study demonstrated that the modified bioretention systems could substantially enhance the removal efficiencies of nutrients from stormwater runoff.

Biodegradation of metal complex Naphthol Green B and formation of iron-sulfur nanoparticles by marine bacterium Pseudoalteromonas sp CF10-13

Treatment of metal complex dye wastewater has attracted growing attention due to the degradation-resistant, high cost and potential hazards of current techniques. This study reported a marine bacterium (Pseudoalteromonas sp CF10-13) with potential performance in decolorization and degradation of a metal complex dye-Naphthol Green B (NGB) at wide ranges of salinity, dye concentration and alkalinity under anaerobic conditions. It was inferred that the secretion of electron mediators in soluble extracellular metabolites by P. sp CF10-13 played important roles in NGB decolorization and degradation through extracellular electron transfer. Naphthalenesulfonate, the major structure in NGB molecule, was further degraded into low-toxic benzamide. Black stable iron-sulfur nanoparticles were formed endogenously avoiding H₂S releasing, exogenous sulfur addition and metal sludge in accumulation. Accordingly, this study provided a cost-effective and eco-friendly biodegradation method to refractory NGB, further promoting the understanding of dye resources recovery.

Seawater toilet flushing sewage treatment and nutrients recovery by marine bacterial-algal mutualistic system

Seawater toilet flushing sewage with excess eutrophic and high salinity brought a great barrier on the municipal wastewater treatment plants. Nutrients recovery and biomass production as potential biofuel feedstock with less energy consumption will be a key challenge in wastewater treatment. In the optimal inoculation of algae and bacteria, a marine bacterial-algal mutualistic system was established to treat synthetic seawater toilet flushing sewage without extra carbon and O₂ addition. It was showed that 85.5% of total nitrogen (TN) (from 200 mg/L), 91.0% of total phosphorus (TP) (from 40 mg/L) and 98.7% of chemical oxygen demand (COD) (from 1600 mg/L) were removed with 4.28 g/L of biomass yield (biomass productivity 159.3 mg/L/d) containing 16.3% lipid and 62.6% protein, which performance mainly achieved by bacteria during first six days and algae functioned subsequently. Both nitrogen and phosphorus removal of the system were mainly assimilation/accumulation. Algal facultative heterotrophia ensured dissolved organic carbon for bacterial utilization and avoiding excessive organic matter produced. The established algal-bacterial system provided a potential energy-efficient and eco-friendly approach for seawater blackwater treatment and nutrients recovery simultaneously.