To solve both the problems of P deficiency in arable soil and excessive waste sludge disposal, we evaluated hydrothermal carbonization of sludge with the aim of recycling sludge P resources for soil amendment. In contrast with pyrochars obtained through pyrolysis, hydrochars generated from hydrothermal carbonization often feature variable properties and therefore require detailed characterization. In this study, sludge-derived hydrochars were evaluated to determine their P content and fractionation, release and availability of P, and P adsorption and desorption behavior. We also assessed changes in P availability after soil was amended with the hydrochars. Our results showed that the chars were rich in total P (up to 25,175 mg kg −1 ), but most of the free fractions were transformed to bound fractions, thereby reducing the available P concentrations. However, available P content was >417 mg kg −1 , which was far higher than soil demand. The hydrochars shifted from releasing to adsorbing P adsorbent when the environmental P concentration increased above 20 mg L −1 . The hydrochars showed a high phosphate adsorption capacity (up to 23,815 mg kg −1 ) and the adsorbed P could be readily released. The addition of 1% P-laden hydrochar significantly enhanced the soil available P content by 8.93 mg kg −1 . These findings have important implications for further development of hydrochar-based P carriers as a slow-releasing fertilizer. Core Ideas Charring transformed P from readily available fractions to moderately available ones. Sludge-derived hydrochars showed the best performance in long-term P release. Sludge-derived hydrochars had better P retention capacity than their feedstock. Applying the sludge-derived hydrochar improved the available P content of soil.
Guanqing Hu,Qingguo Zhang,Yongde Yan,Yun Xue,Fuqiu Ma,Yuelin Wang,Xin Liu,Jinlong Song
With the rapid development of the global nuclear industry, substantial amounts of radioactive tributyl phosphate (TBP) have accumulated during the PUREX process. Prolonged accumulation poses significant environmental risks. Therefore, this study proposes an efficient molten salt oxidation (MSO) method for the treatment of gelled TBP. Comprehensive thermal analysis data indicate that the oxidation process of gelled TBP primarily consists of three stages. The composition of the waste salts after the MSO process was analyzed using X-ray diffraction spectroscopy. Fourier transform infrared spectroscopy revealed that the primary functional groups in gelled TBP were progressively degraded with increasing temperature. Scanning electron microscopy clearly illustrated the decomposition process of gelled TBP. X-ray photoelectron spectroscopy results identified the predominant forms of residual substances. The generated exhaust gas was analyzed using gas mass spectrometry and chromatography. Additionally, through DFT calculations of TBP, the possible reaction mechanism of TBP in the molten salts was deduced. In the molten state, carbonate can effectively absorb P 2 O 5 and eventually form stable NaPO 3 , which is the reason for the 94.90 % retention rate of phosphorus element. During the experimental process, the degradation rate of gelled TBP reached as high as 99.99 %. The MSO method proposed in this study shows great potential for the treatment of liquid organic waste.
Taurine is a component that tends to be deficient in fish diets that contain higher plant-derivative proteins. Acanthopagrus schlegelii juveniles (IBW − 11.28 g) were fed nine diets containing SPC levels (SPC40, SPC60, SPC80 and SPC100), or supplemented with 5 g/kg of taurine at each replacement level. Our results showed higher WGR and SGR in SPC60 + TAU (WGR; 224.67, SGR; 2.10) followed by SPC40 + TAU (WGR; 221.75, SGR; 2.09). Phosphorus retention efficiency was significantly raised as the SPC increased when compared with the control diet. Taurine addition showed an incline in the nitrogen retention efficiency. An effect was observed within FR between fish and the SPC content. ADCs of dry matter, crude lipid and phosphorous were affected by SPC, while taurine addition affected only crude lipid. A significant effect was seen in ash and phosphorus by the SPC and taurine. TAU supplementation showed an increased T-AOC activity in the SPC80 + TAU (1.90), while malondialdehyde and catalase activity were reduced except in completely replaced fish meal groups. It could be concluded that black sea bream can accept the substitution of FM with 60% of SPC while at the inclusion of dietary TAU (5 g/kg) growth could be improved.
危险品化学品经营许可证（带存储）