Triazophos and chlorpyrifos are organophosphorus pesticides (OPs), and their primary hydrolytic metabolites are 1-phenyl-3-hydroxy-1,2,4-triazole (BZC) and 3,5,6-trichloro-2-pyridinol (TCP). In this study, the adsorption and degradation of triazophos, chlorpyrifos, BZC and TCP were investigated in paddy soil from Chaohu Lake, China. Adsorption tests demonstrated that the adsorption of these compounds to soils could be described by the Freundlich equation. Moreover, chlorpyrifos displayed the highest affinity for adsorption, followed by triazophos, BZC and TCP. Degradation of these compounds in non-sterile soil followed first-order exponential decay kinetics, and the half-life (t(1/2)) of these contaminants ranged from 8.40 to 44.34 d. Sterilization of soil decreased the degradation rate, indicating that microorganisms played a significant role in the degradation of these compounds. The values of t(1/2) and K(oc) were fitted to obtain models that could predict the leaching potential of the contaminants from soil. Compared to their parent compounds, BZC and TCP showed high potential for leaching into groundwater. The inoculation of OPs-degrading bacterium (Diaphorobacter sp. GS-1) removed 95.38%, 100% and 100% of triazophos, chlorpyrifos and BZC in paddy soil after 21 d, respectively. The pollution risk of triazophos, chlorpyrifos and BZC could be greatly decreased by inoculating soil with Diaphorobacter sp. GS-1, which decreases the t(1/2) of the contaminants. 相似文献
A self-design bioreactor system employing a fixed bed operation process with immobilized Bacillus subtilis AYC beads for NH4
+-N
removal from slightly polluted water was proposed. Polyvinyl alcohol and Na-alginate were used as a gel matrix to entrap Bacillus
subtilis AYC to form the immobilized beads. The NH4
+-N removal process was studied in a intermittent operation mode to examine
the start-up and steady state behaviors of the immobilized AYC in the reactor. The results indicated that the reactor was in the start-up
state during the first week. NH4
+-N began to be steadily removal since the second week, and the nitrogen removal rate was between
84.61% and 96.19% when the hydraulic retention time (HRT) was 30 min. To apply Bacillus subtilis AYC to develop a practical
nitrogen removal system and further understand its nitrogen removal ability, the bioreactor was continuously operated under different
experimental perameters. The results showed that under the optimum conditions of an HRT of 20 min and DO of 3.77–5.80 mg/L,
the NH4
+-N removal rate reached 99.55%. The NH4
+-N removal rate increased as the C/N ratio increased. However, a high C/N may
cause a high residual carbon level in the effluent, therefore, the most suitable C/N ratio was 10. In addition, the results showed that
the bioreactor system could remove many types of nitrogen such as NH4
+-N, NO3??-N and organic-N, and had a good performance for
inorganic nitrogen removal from sewage. 相似文献
The reuse of human wastes as biofertilizer resources offers a new option for meeting the growing demand for food and addressing poor soil productivity. Feces and black water are ubiquitous human wastes that usually require proper treatment, such as composting and anaerobic digestion, to remove potentially harmful substances before they can be applied as fertilizers. As an effective treatment technology for livestock farming wastes, the ectopic fermentation bed system (EFS) provides a new means of treating human waste and producing organic fertilizer from decomposed filler. Therefore, the objective of this study was to evaluate and compare the nutrient content and fertilizer potential of decomposed fillers obtained after EFS treatment of human feces and black water under different application conditions. The results showed that the application of fillers increased the yield of pakchoi by 3.60?29.32% and nutrient uptake by 8.09?83.45% compared to the CK, which could effectively promote the growth of pakchoi. This approach also improved the quality of pakchoi and enhanced soil fertility, and differences were observed in the effects of different kinds and application amounts of fillers. Soil EC was the soil property that had the greatest effect on the growth characteristics of pakchoi in this study. These findings help to better clarify the agronomic value of human wastes, but the effects of long-term filler application need to be further explored.