PAHs removal by soil washing with thiacalix[4]arene tetrasulfonate.

Remediating soil contaminated with polycyclic aromatic hydrocarbons (PAHs) presents a significant environmental challenge due to their toxic and carcinogenic properties. Traditional PAHs remediation methods-chemical, thermal, and bioremediation-along with conventional soil-washing agents like surfactants and cyclodextrins face challenges of cost, ecological harm, and inefficiency. Here we show an effective and environmentally friendly calixarene derivative for PAHs removal through soil washing. Thiacalix[4]arene tetrasulfonate (TCAS) has a unique molecular structure of a sulfonate group and a sulfur atom, which enhances its solubility and facilitates selective binding with PAHs. It forms host-guest complexes with PAHs through π-π stacking, OH-π interactions, hydrogen bonding, van der Waals forces, and electrostatic interactions. These interactions enable partial encapsulation of PAH molecules, aiding their desorption from the soil matrix. Our results show that a 0.7% solution of TCAS can extract approximately 50% of PAHs from contaminated soil while preserving soil nutrients and minimizing adverse environmental effects. This research unveils the pioneering application of TCAS in removing PAHs from contaminated soil, marking a transformative advancement in resource-efficient and sustainable soil remediation strategies.

Inducement mechanism and control of self-acidification in elemental sulfur fluidizing bioreactor.

The sulfur fluidizing bioreactor (S0FB) has significant superiorities in treating nitrate-rich wastewater. However, substantial self-acidification has been observed in engineering applications, resulting in frequent start-up failures. In this study, self-acidification was reproduced in a lab-scale S0FB. It was demonstrated that self-acidification was mainly induced by sulfur disproportionation process, accounting for 93.4 % of proton generation. Supplying sufficient alkalinity to both the influent (3000 mg/L) and the bulk (2000 mg/L) of S0FB was essential for achieving a successful start-up. Furthermore, the S0FB reached 10.3 kg-N/m3/d of nitrogen removal rate and 0.13 kg-PO43-/m3/d of phosphate removal rate, respectively, surpassing those of the documented sulfur packing bioreactors by 7-129 times and 26-65 times. This study offers a feasible and practical method to avoid self-acidification during restart of S0FB and highlights the considerable potential of S0FB in the treatment of nitrate-rich wastewater.

Tracking composition of microbial communities for simultaneous nitrification and denitrification in polyurethane foam.

The process of simultaneous nitrification and denitrification (SND) of immobilized microorganisms in polyurethane form is discussed. The effect of different positions within the polyurethane carrier on microbial community response for the SND process is investigated by a combination of denaturing gradient gel electrophoresis profiles of the 16S rRNA gene V3 region and scanning electron microscopy. Results show that polyurethane, which consists of a unique porous structure, is an ideal platform for biofilm stratification of aerobe, anaerobe and facultative microorganisms in regard to the SND process. The community structure diversity response to different positions was distinct. The distributions of various functional microbes, detected from the surface aerobic stratification to the interior anaerobic stratification of polyurethane, were mainly nitrifying and denitrifying bacteria. Meanwhile aerobic denitrifying bacteria such as Paracoccus sp., Agrobacterium rubi and Ochrobactrum sp. were also adhered to the interior and surface of polyurethane. The SND process occurring on polyurethane foam was carried out by two independent processes: nitrogen removal and aerobic denitrification.

[Study on preparation and performance of a biological carrier with tourmaline].

In order to strengthen the activity of biofilm on the carrier surface, the tourmpaline on polyurethane (TPU) carrier was prepared using waterborne polyurethane as medium. The physical properties of TPU carrier were characterized by scanning electron microscope(SEM) and water absorbency, and its effect on biofilm biomass and nitrifying ability was studied. The results showed that the tourmaline loading amount of TPU carrier can be affected by waterborne polyurethane. Tourmaline can optimize the number of polar groups of the TPU carrier and the pH of the nitrification condition. The amount of nitrobacteria and nitrate bacteria irreversibly adsorbed on the TPU carrier was increased by 74.82% and 71.89% , respectively. Correspondingly, the removing rate of NH+4 -N and NO-2 -N has risen by 8.12% and 9.08%, respectively, compared to the control without carrier. The TPU carrier was indicated to promote the nitrification.

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFX.

Although the treatment technology of sulfamethoxazole has been investigated widely, there are various issues such as the high cost, inefficiency, and secondary pollution which restricted its application. Bioflocculant, as a novel method, is proposed to improve the removal efficiency of PPCPs, which has an advantage over other methods. Bioflocculant MFX, composed by high polymer polysaccharide and protein, is the metabolism product generated and secreted by Klebsiella sp. In this paper, MFX is added to 1 mg/L sulfanilamide aqueous solution substrate, and the removal ratio is evaluated. According to literatures review, for MFX absorption of sulfanilamide, flocculant dosage, coagulant-aid dosage, pH, reaction time, and temperature are considered as influence parameters. The result shows that the optimum condition is 5 mg/L bioflocculant MFX, 0.5 mg/L coagulant aid, initial pH 5, and 1 h reaction time, and the removal efficiency could reach 67.82%. In this condition, MFX could remove 53.27% sulfamethoxazole in domestic wastewater, and the process obeys Freundlich equation. R(2) value equals 0.9641. It is inferred that hydrophobic partitioning is an important factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water; meanwhile, some chemical reaction probably occurs.

Effect of aridification on the replacement of zonic species, Stipa baicalensis Roshev., by azonic species, Leymus chinensis Tzvel., in the steppe of China.

The perennial grass Stipa baicalensis is the zonic species in the steppe of China, but is currently being replaced by the azonic species of Leymus chinensis. In this area, aridification is on the increase; therefore, we hypothesize that water competition plays a significant role in this succession. The limit of osmotic adjustment in S. baicalensis (13.94%-16.30% PEG) was much lower than that in L. chinensis (17.20%-24.50% PEG) in response to drought. The synoptic causal model accounted for most of the variation in the process of physiological regulation as indicated by the small residual effect (0.121-0.161). These results demonstrated that the two species dealt with drought in different ways. Stomata of L. chinensis acted more directly on transpiration, and the advantage in water competition resulted from the powerful stomatal control. On the other hand, S. baicalensis was more easily affected by non-stomatal limitation which was physiologically inactive in response to drought. Results supported the hypothesis above. S. baicalensis was more susceptible to the damage of aridification and was less competitive to water than L. chinensis.

[Feasibility of treatment of micro-pollutant water polluted by nitrobenzene with IBAC-process].

The performance and feasibility of immobilization biological activated carbon (IBAC) were investigated to treat micro-pollutant water containing nitrobenzene. IBAC has been developed on the granular activated carbon by immobilization of selected and acclimated species of engineering bacteria to treat the micro-pollutant water containing nitrobenzene. The IBAC removal efficiencies for nitrobenzene, permanganate index, turbidity, UV, ammonia and nitrite were compared with granular activated carbon (GAC) process. Biological toxicity of influent and effluent of filter were determined. Amount of bacteria in carbon was measured when carbon filter was inoculated and circulated stably. The results showed that compared with GAC, it took short time for IABC to startup and recover to normal after impact burden. In addition, IBAC was more effective to treat micro-pollutants. In order to ensure security of drinking water, the influent nitrobenzene should be controlled below 26 microg/L. Effluent biological toxicity treated with IBAC was less than that with GAC. The performance of IBAC was much better than that of GAC. Amount of bacteria in both activated carbon filter increased first and then declined from inlet to outlet.