To improve the denitrification characteristics of anaerobic denitrifying bacteria and obviate the disadvantage of use of explosive hydrogen gas, tourmaline, a polar mineral, was added to the hydrogenotrophic denitrification system in this study. Microbial reduction of nitrate in the presence of tourmaline was evaluated to assess the promotion effect of tourmaline on nitrate biodegradation. The experiment results demonstrated that tourmaline speeded up the cultivation process of bacteria from 65 to 36 days. After domestication of the bacteria, nitrate (50 mg NO₃ ⁻–N L⁻¹) was completely removed within 3 days in the combined tourmaline–bacteria system, and the generated nitrite was also removed within 8 days. The reduction rate in this system is higher relative to that in the bacteria system alone. Efficient removal of nitrate by tourmaline-supported anaerobic bacteria (without external hydrogen input) indicated that tourmaline might act as the sole hydrogen donor to sustain autotrophic denitrification. Besides the production of hydrogen, the promoted activity of anaerobic denitrifying bacteria might be caused by the change of water properties, e.g., the pH of aqueous solutions was altered to about 8.0 and the oxidation–reduction potential decreased by 62 % in the tourmaline system. The distinctive effects of tourmaline on bacteria were related to its electric properties.

Native arbuscular mycorrhizal fungi (AMF) generally provide more effective assistance for phytoremediation to remove heavy metal (HM) from polluted soils than non-native AMF. Nevertheless, it is a time-consuming work to isolate, identify, and propagate AMF inoculum for practical application. This study aims to explore an alternative method to improve the phytoremediation efficiency of Bidens parviflora using domesticated AMF under HM stress condition for a certain period of time. Our results showed that Funneliformis mosseae inoculation alleviated oxidative damage to plant membranes by enhancing activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. Furthermore, mycorrhizal plants had higher chlorophyll concentration, photosynthesis efficiency, and root Pb content to protect the aerial parts from damage. These protective mechanisms were found to be more efficient in domesticated AMF inoculation compared with non-domesticated AMF inoculation. Overall, this study suggests that F. mosseae domesticated for 12 months could greatly enhance plant root Pb accumulation and plant growth mainly through strengthening antioxidant defenses as well as the photosynthesis efficiency under Pb stress conditions. Plants inoculated with pre-domesticated AMF provided a promising new strategy to enhance phytoremediation of Pb-contaminated soils.

A photodegradation technology based on the combination of ultraviolet radiation with ozone (UV/O₃) for degrading tri(chloropropyl) phosphate (TCPP) was developed in the present study. Parameters affecting the degradation of TCPP were optimized, and the developed technology was successfully applied to degrade TCPP in two real wastewater samples. The results showed that reaction time, ozone concentration, the initial acidity of reaction solution, and the initial concentration of TCPP in aqueous solution contributed to the degradation efficiency of TCPP. Under the optimized disposal conditions, 100 mg/L of TCPP aqueous solution with a pH value of 7 can be degraded effectively in 60 min with an ozone concentration of 66.2 mg/L. In detail, the yield rates of Cl⁻and PO₄³⁻was high up to 98.9 and 98.2 %, respectively; and total organic carbon (TOC) removal rate was high up to 94.3 %. Method application demonstrated that TCPP can be degraded effectively in pond water. However, only 83.2 and 61.9 % of Cl⁻and PO₄³⁻were produced, and the TOC removal rate was only 81.3 % after 60 min exposure in the effluent discharged from a wastewater treatment plant. Therefore, the presence of interferences may hinder the degradation of TCPP in real wastewater, but its potential application for real wastewater is promising in the future after appropriate domestication and evaluation.

This study evaluated the effects of two surfactants (i.e., Tween 80 and SDS) on biodegradation of crude oil by mixed bacterial consortium in soil-aqueous system. The mixed bacterial consortium was domesticated from the activated sludge of cooking plant through a progressive domestication process. High-throughput sequencing analysis revealed that Rhodanobacter sp. was the dominant bacteria. The higher CMCₑff value for two surfactants was observed in soil-aqueous system compared with that in aqueous system, which was likely due to their adsorption onto soil particles. Either Tween 80 or SDS can be utilized as carbon source and promote the growth of mixed bacterial consortium. Further findings evidenced that the degradation of crude oil can be enhanced by adding either Tween 80 or SDS. The performance of Tween 80 was generally superior to SDS for the crude oil degradation. The highest crude oil degradation efficiency was 42.2 and 31.0% under the conditions of 5 CMCₑff of Tween 80 and 2 CMCₑff of SDS, respectively. Furthermore, the degradation efficiency of crude oil in remediation experiment (i.e., 77%) evidenced that the integration of adding Tween 80 and inoculating mixed bacterial consortium was effective for crude oil-contaminated soil decontamination.

Nitrite accumulation usually occurred when domesticating the idle aerobic activated sludge. A sequencing batch reactor (SBR) was used to investigate whether the short-cut nitrification sludge could be cultivated using the idle sludge as inoculated sludge. The results showed that the nitrification process consisted of three stages. In the first stage, the activity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were very low with almost no nitrification performance. In the second stage, the activity of AOB started to recover with the effluent NH₄⁺-N gradually decreased to 0.29 mg L⁻¹, while NOB was alternately inhibited by free ammonia (FA), free nitrous acid (FNA), and nitrite. The effluent NOₓ⁻-N was mainly NO₂⁻-N with an average nitrite accumulation ratio of 74.00%. In the third stage, the nitrification altered from short-cut nitrification to complete nitrification, and the nitrification kinetics of AOB and NOB were both well-fitted to the Monod equation (R² > 0.92). The variations of effluent pH and ORP between cycles could indicate the recovery stage of the nitrifying ability. Through monitoring the curves of effluent pH and ORP, when the domestication process is between the pH peak and ORP plateau, the short-cut nitrification sludge could be cultivated. This study revealed the mechanism of nitrite accumulation during the domestication of long-term idle aerobic activated sludge, and established a control strategy to accelerate the domestication.