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621.
622.
对EGSB反应器处理五氯苯酚(PCP)废水的运行条件以及PCP的降解途径作了研究.结果表明,在进水PCP浓度为95mg/L,COD浓度为5000mg/L时,出水回流比为90,水力停留时间(HRT)为16h的条件下,出水PCP和COD浓度达到排放要求(PCP<0.1mg/L,COD<100mg/L),反应器PCP容积负荷142.5g/(m3·d),有机容积负荷为COD7.5kg/(m3·d).PCP在EGSB反应器中主要脱氯产物是2,3,4,5-TeCP,2,3,5-TCP以及2,3,4,6-TeCP,表明PCP主要通过邻位脱氯产生2,3,4,5-TeCP,再脱氯产生2,3,5-TCP,部分PCP首先间位脱氯产生2,3,4,6-TeCP. 相似文献
623.
624.
Birgit Daus Michael Hempel Holger Weiss 《Environmental pollution (Barking, Essex : 1987)》2010,158(11):3439-3444
Groundwater polluted with phenylarsenicals from former warfare agent deposits and their metabolites was investigated with respect to the behavior of relevant arsenic species. Depth profiles at the estimated source and at about 1 km downgradient from the source zone were sampled. The source zone is characterized by high total arsenic concentrations up to 16 mg L−1 and is dominated by organic arsenic compounds. The concentrations in the downgradient region are much lower (up to 400 μg L−1) and show a high proportion of inorganic arsenic species. Iron precipitation seems to be an effective mechanism to prevent dispersion of inorganic arsenic as well as phenylarsonic acid. Reductive conditions were observed in the deeper zone with predominant occurrence of trivalent arsenic species. The inorganic species are in redox equilibrium, whereas the phenylarsenic compounds have variable proportions. Methylphenylarsinic acid was identified in groundwater in traces which indicates microbial degradation activity. 相似文献
625.
从长期被石油污染的土壤中筛选得到一株以蒽为惟一碳源的混合菌T2,在接种量为1%,pH为7,温度为30℃,摇床转速为120r/min,蒽的初始浓度为100mg/L的条件下培养5d后,其对蒽的降解率可以达到56.6%。通过单因素实验和正交实验对菌种T2的培养条件进行研究,得到菌种T2的最佳培养条件为:接种量为5%,pH为6,温度为35℃,蒽的初始浓度为40mg/L时,最适合菌种生长。另外,菌种T2对蒽的降解动力学实验的结果表明,蒽的残留浓度Y(mg/L)与时间t(h)符合方程y=2.544e(-0.00275)t. 相似文献
626.
627.
628.
Hydrothermal decomposition of pentachlorophenol in subcritical and
supercritical water with sodium hydroxide addition 总被引:1,自引:0,他引:1
Hydrothermal decomposition of pentachlorophenol (PCP, C6HC150), as the probable human carcinogen, was investigated in a tubular reactor under subcritical and supercritical water with sodium hydroxide (NaOH) addition. The experiments were conducted at a temperature range of 30(0-420℃ and a fixed pressure of 25 MPa, with a residence time that ranged from 10 s to 70 s. Under the reaction conditions, the initial PCP concentrations were varied from 0.25 to 1.39 mmol/L, and the NaOH concentrations were varied from 2.5 to 25 times of the concentrations of PCP. The result of this study showed that PCP conversion in supercritical water was highly dependent on the reaction temperature, residence time, and NaOH concentration. PCP conversion in subcritical water is, however, only dependent on reaction temperature. NaOH concentration and residence times were found to have little effect on PCP conversion in subcritical condition. It was found that NaOH concentration affected the dechlorinations of PCP in the supercritical water. The intermediates detected were proposed to be tetrachlorophenol and trichlorophenol, respectively. 相似文献
629.
Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors (SMBRs) operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR (CSMBR) while the other was dosed with powdered activated carbon (PAC) (PAC-amended SMBR, PSMBR). The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d (576 h) was 5.87 L/h with average hydraulic residence time (HRT) of 5.97 h and that of PSMBR during a steady periodic state of 30 d (720 h) was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand (COD) removal efficiency of CSMBR was 89.29% with average organic loading rate (OLR) at 4.16 kg COD/(m^3.d) while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/(m^3.d). COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry (300 mg/L). Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR. 相似文献
630.
苏南地区耕地质量评价与分区保护研究 总被引:3,自引:0,他引:3
耕地质量监测与评估研究是我国耕地保护工作的重要支撑。针对苏南地区耕地保护面临的新问题,整合农用地分等定级、多目标地球化学调查和土壤侵蚀等相关研究资料,重构耕地综合质量评估指标体系,综合运用空间分析、加权综合和聚类分析方法,根据耕地基础地力、耕地健康和耕地外部环境的空间分异和组合特征,识别优先保护、地力提升、污染治理和水土保持等耕地类型,分类讨论耕地保护与整治路径。分析表明:苏南地区现状耕地中,优质耕地占比不足65%,近30%的耕地基础地力较差,超过5%的耕地受到水土流失、重金属污染威胁。其中,优质耕地集中于茅山以东的太湖平原和沿江平原地区,茅山以西地区基础地力相对较差,宁镇沿江、太湖东北岸部分地区土壤重金属污染和水土流失风险较高,需要因地制宜开展地力提升、土壤修复、水土保持和农业结构调整等治理措施,以增强地产农产品质量安全。 相似文献