Development of immobilized novel fungal consortium for the efficient remediation of cyanide-contaminated wastewaters

Harmless treatment of cyanide tailings by functional bacteria: Degradation of cyanide and the secondary pollutant ammonia nitrogen

The eco-friendly treatment of cyanide tailings (CT) using microorganisms is a cost-effective and promising technology. However, this process often generates the secondary pollutants, such as ammonia nitrogen (NH4+-N), which can adversely impacts the surrounding environment. The accumulation of NH4+-N is also toxic to cyanide-degrading microorganisms, presenting a significant challenge in achieving simultaneous cyanide degradation and NH₄⁺-N mitigation. In this study, a group of functional bacteria CG305-1 with the ability to degrade cyanide and perform nitrification and denitrification was successfully enriched for the first time and used to treat CT by in situ microbial drenching technology. Results demonstrated that the total cyanide (CNT) concentration in the leaching solution decreased from 49.96 ± 1.51 mg/L to 0.19 ± 1.11 mg/L. NH₄⁺-N was degraded to 0.25 ± 0.18 mg/L, and nitrate nitrogen (NO3--N) was reduced to 0.41 ± 0.20 mg/L. Furthermore, CNT in the CT leachate was reduced to 0.94 ± 0.11 mg/L, meeting the storage standard for CT leachate (CNT < 5 mg/L). The potential synergistic microbial degradation mechanisms were elucidated through Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Metagenomic sequencing. This study provides significant insights into green and sustainable methods for the harmless treatment of CT.

Bioremediation of metal cyanide complexes from electroplating wastewater for long-term application using Agrobacterium tumefaciens SUTS 1 and Pseudomonas monteilii SUTS 2

The purpose of this study was to investigate the optimum conditions, including aerobic and anoxic conditions, for operating a long-term bioreactor system to decrease the toxicity of industrial electroplating wastewater effluents containing metal cyanide using Agrobacterium tumefaciens SUTS 1 and Pseudomonas monteilii SUTS 2. The initial results revealed that bacteria performed better under aerobic conditions than under anoxic conditions. An aerobic bioreactor system was subsequently set up in a long-term study lasting 30 days under optimum operating conditions. Both mixed-culture bacteria and indigenous bacteria promoted the high-efficiency treatment of cyanide and metals in the first 7 days of the study. When the system had high removal rates, cyanide removal was greater than that of zinc, copper, nickel, and chromium (CN- > Zn > Cu > Ni > Cr), with removal efficiencies of 96.67%, 93.93%, 74.17%, 63.43%, and 44.65%, respectively, with residual concentrations of 0.15 ± 0.01, 0.24 ± 0.005, 0.03 ± 0.002, 18.41 ± 0.06 and 14.26 ± 0.15 mg/L, respectively. The cell concentration in the bioreactor increased to approximately 107 CFU/mL over 30 days from initial cell concentrations of 6.15 × 105 CFU/mL and 1.05 × 103 CFU/mL for the mixed culture and indigenous inoculation, respectively. These results implied that the bacteria were resistant to heavy metal toxicity. The addition of an appropriate carbon source with sufficient aeration to a bioreactor resulted in increased cyanide degradation.

Sustainable management and valorization of biomass wastes using synthetic microbial consortia

In response to the persistent expansion of global resource demands, considerable attention has been directed toward the synthetic microbial consortia (SMC) within the domain of microbial engineering, aiming to address the sustainable management and valorization of biomass wastes. This comprehensive review systematically encapsulates the most recent advancements in research and technological applications concerning the utilization of SMC for biomass waste treatment. The construction strategies of SMC are briefly outlined, and the diverse applications of SMC in biomass wastes treatment are explored, with particular emphasis on its potential advantages in waste degradation, hazardous substances control, and high value-added products conversion. Finally, recommendations for the future development of SMC technology are proposed, and prospects for its sustainable application are discussed.

Mechanisms of total phosphorus removal and reduction of β-lactam antibiotic resistance genes by exogenous fungal combination activated sludge

This study utilized Trichoderma and activated sludge to construct combined activated sludge (TAS). The metagenomic approach was employed to examine the shifts in microbial community structure and function of TAS under amoxicillin stress and investigate the mechanism underlying the reduction of β-lactam antibiotic resistance genes (β-ARGs). The findings demonstrated that the elevated aundance of glpa, glpd, ugpq, glpq, and glpb were primarily responsible for the reduction in total phosphorus (TP) removal by TAS. The increased abundance of Proteobacteria and Verrucomicrobia led to enhanced expression of ugpb, phnd, and phne, thereby improving the TP removal of TAS. Furthermore, antibiotic inactivation has gradually become the primary antibiotic resistance mechanism in TAS. Specifically, an increase in the abundance of OXA-309 in TAS will decrease the probability of amoxicillin accumulation in TAS. A decrease in β-ARGs diversity confirmed this. This study presents a novel approach to reducing antibiotic and ARG accumulation in sludge.

Advances in responses of microalgal-bacterial symbiosis to emerging pollutants in wastewater

Nowadays, emerging pollutants are widely used and exist in wastewater, such as antibiotics, heavy metals, nanoparticle and microplastic. As a green alternative for wastewater treatment, microalgal-bacterial symbiosis has been aware of owning multiple merits of low energy consumption and little greenhouse gas emission. Thus, the responses of microalgal-bacterial symbiosis to emerging pollutants in wastewater treatment have become a hotspot in recent years. In this review paper, the removal performance of microalgal-bacterial symbiosis on organics, nitrogen and phosphorus in wastewater containing emerging pollutants has been summarized. The adaptation mechanisms of microalgal-bacterial symbiosis to emerging pollutants have been analyzed. It is found that antibiotics usually have hormesis effects on microalgal-bacterial symbiosis, and that microalgal-bacterial symbiosis appears to show more capacity to remove tetracycline and sulfamethoxazole, rather than oxytetracycline and enrofloxacin. Generally, microalgal-bacterial symbiosis can adapt to heavy metals at a concentration of less than 1 mg/L, but its capabilities to remove contaminants can be significantly affected at 10 mg/L heavy metals. Further research should focus on the influence of mixed emerging pollutants on microalgal-bacterial symbiosis, and the feasibility of using selected emerging pollutants (e.g., antibiotics) as a carbon source for microalgal-bacterial symbiosis should also be explored. This review is expected to deepen our understandings on emerging pollutants removal from wastewater by microalgal-bacterial symbiosis.