微生物金矿处理技术进展及应用前景

回顾了已经出现的多种微生物金矿处理技术,对他们的作用机理、浸金结果、完善措施和存在的问题等进行了综合评述,在此基础上,作者探讨了微生物金矿处理技术的研究方向及其工业化前景。     

Dairy Manure Treatment,Digestion and Nutrient Recovery as a Phosphate Fertilizer

A combined approach of biological treatment, solids digestion and nutrient recovery was tested on dairy manure. A sequencing batch reactor (SBR) was operated in three modes, in order to optimize nutrient (nitrogen and phosphorus) removals. The highest average removal efficiencies of 91% for NH₄-N, 59% for PO₄-P and 80% for total chemical oxygen demand (COD) were achieved. Staining experiments suggested the coexistence of glycogen and phosphorus accumulating organisms. Anaerobic digestion of wasted bio-solids was able to produce a PO₄-P concentration of 70 mgL^?1 in the supernatant. A pilot-scale experiment, designed to recover phosphorus in the supernatant as struvite (magnesium ammonium phosphate), was able to remove 82% of soluble PO₄-P.     

Local Capacity for Groundwater Protection in Ontario

Preventing groundwater contamination is vastly cheaper than remediation. Recognizing this, attention in water and land management agencies in North America increasingly turn to groundwater protection. Local agencies, such as municipalities and watershed management districts, are vital to successful groundwater protection, but they face daunting challenges. In the United States, senior governments have recognized these challenges and provide considerable support for local agencies. In Ontario, Canada, local agencies are, to a much greater extent, on their own. The aims in this paper are to analyze factors that shape local capacity for groundwater protection, focusing on Ontario, and to recommend avenues for capacity building. Interrelationships among five dimensions of capacity (technical, financial, institutional, social, and political) are explored through an analysis of three smaller Ontario communities: City of Guelph (population 93,400), Town of Orangeville (population 22,188), and Town of Erin (population 11,000). Size clearly influences capacity for groundwater protection. However, other considerations unrelated to size appear to be as important. These other factors include the ability to form horizontal and vertical linkages with external agencies, political leadership and commitment, and citizen involvement. Thus, smaller communities in Ontario (and other jurisdictions with limited senior government support) would do well to focus on these areas at the same time as they develop their technical, financial, and institutional capacity.     

Nitrogen Balance in the Lower Fraser River Basin of British Columbia

/ A study was conducted to determine the extent of nitrogenpollution in agricultural lands in the Lower Fraser River basin of BritishColumbia, Canada. The specific objectives were to determine the distributionof leachable nitrogenand estimate the nitrogen concentration in groundwaterrecharges. Nitrogen and water mass balances were conducted on the entirebasin and on each of the four districts comprising it over the period1971-1991 in intervals of five years. The results indicated that the averagenitrogen concentration in the groundwater recharge for the entire basin rosefrom nondetectable in 1971 to 6 mg/liter in 1991. Estimates for theindividual districts ranged from 4 to 14 mg/liter in Central Fraser and fromnondetectable to 7 mg/liter in Fraser-Cheam and 3 mg/liter in both GreaterVancouver and Dewdney-Alouette. So far, excessive levels of nitrogen areconfined to Central Fraser. Although they have remained within the acceptablerange, nitrogen concentrations in the other three districts have definitelyincreased over the 20-year study period. Sensitivity analyses indicated thatanimal manure and fertilizer had the largest contribution in groundwaterrecharge. Decreasing the rate of manure application to agricultural lands issuggested as the most practical way of reducing nitrogen pollution in CentralFraser.KEY WORDS: Nitrogen balance; Water balance; Sensitivity analysis     

离心模型试验技术在环境岩土工程中的应用现状与展望

首先简单介绍了离心模型试验技术的发展状况,然后探讨了其在环境岩土工程中的应用,研究了模型和原型的相似规律,提出了环境岩土工程离心模型试验的发展方向.     

利用剩余活性污泥的生物吸附降低城市污水污泥重金属含量

对香港沙田和广州大坦沙污水处理厂的污水、污泥作了初步的生物吸附试验，结果表明：少量活性的污泥能够显著降低污水中Ｃｕ、Ｚｎ、Ｎｉ的浓度，污泥浓度为０。．０６ｇ／Ｌ时，广州污水上述３种重金属的去除率分别为８２％，６９％和５１％，因此回流活性污泥到一沉池可有效降低上述金属进入生物反应池。     

Microwave Pretreatment for Enhancement of Phosphorus Release from Dairy Manure

Both the advanced oxidation process (AOP) using a combination of hydrogen peroxide addition and microwave heating (H₂O₂/microwave), and the microwave heating process were used for solubilization of phosphorus from liquid dairy manure. About 80% of total phosphate was released into the solution at a microwave heating time of 5 min at 170°C. With an addition of H₂O₂, more than 81% of total phosphate could be released over a reaction period of 49 h at ambient temperature. The AOP process could achieve up to 85% of total phosphate release at 120°C. The results indicated that both the microwave, and the AOP processes could effectively release phosphate from liquid dairy manure. These processes could serve as pretreatments for phosphorus recovery from animal wastes, and could be combined with the struvite crystallization process to provide a new approach in treating animal wastes.     

Salting-in and salting-out effects of ionic and neutral osmotica on limonene and linalool Henry's law constants and octanol/water partition coefficients

Foliar emission rates of plant-generated volatile monoterpenes depend on monoterpene partitioning between air, aqueous and lipid-phases in the leaves. While Henry's law constants (H pc, equilibrium gas/water partition coefficient) and octanol/water partition coefficients (K OW) for pure water have been previously used to simulate monoterpene emissions from the leaves, aqueous phase in plants is a complex solution of electrolytes and neutral osmotica. We studied the effects of dissociated compounds KCl and glycine and sugars glucose, sorbitol and sucrose with concentrations between 0 and 1M on H pc and K OW values for limonene and linalool. Linalool with ca. 1500-fold lower H(pc) (2.62 Pa m(3)mol(-1) for pure water at 30 degrees C) and ca. 30-fold lower K OW (955 mol mol(-1) for pure water at 25 degrees C) is the more hydrophilic compound of the two monoterpenes. H pc of both monoterpenes increased with increasing concentration of both ionic compounds and sorbitol, but decreased with increasing glucose and sucrose concentrations. The salting-out coefficients for H pc (kH) were ca. an order of magnitude larger for more hydrophilic compound linalool than for more hydrophobic limonene. For linalool, co-solutes modified H pc by 30-50% at the highest concentration (1M) tested. The effect of temperature on the salting-out coefficient of KCl was minor. As with H pc, K OW increased with increasing the concentration of KCl, glycine and sorbitol, and decreased with increasing glucose and sucrose concentrations. For limonene, co-solutes modified K OW by 20-50% at the highest concentration used. For linalool, the corresponding range was 10-35%. Salting-out coefficients for H pc and K OW were correlated, but the lipid-solubility was more strongly affected than aqueous solubility in the case of limonene. Overall, these data demonstrate physiologically important effects of co-solutes on H pc and K OW for hydrophilic monoterpenes and on K OW for hydrophobic monoterpenes that should be included in current emission models.     

Temperature dependencies of Henry's law constants and octanol/water partition coefficients for key plant volatile monoterpenoids

To model the emission dynamics and changes in fractional composition of monoterpenoids from plant leaves, temperature dependencies of equilibrium coefficients must be known. Henry's law constants (H(pc), Pa m3 mol(-1) and octanol/water partition coefficients (K(OW), mol mol(-1)) were determined for 10 important plant monoterpenes at physiological temperature ranges (25-50 degrees C for H(pc) and 20-50 degrees C for K(OW)). A standard EPICS procedure was established to determine H(pc) and a shake flask method was used for the measurements of K(OW). The enthalpy of volatilization (deltaH(vol)) varied from 18.0 to 44.3 kJ mol(-1) among the monoterpenes, corresponding to a range of temperature-dependent increase in H(pc) between 1.3- and 1.8-fold per 10 degrees C rise in temperature. The enthalpy of water-octanol phase change varied from -11.0 to -23.8 kJ mol(-1), corresponding to a decrease of K(OW) between 1.15- and 1.32-fold per 10 degrees C increase in temperature. Correlations among physico-chemical characteristics of a wide range of monoterpenes were analyzed to seek the ways of derivation of H(pc) and K(OW) values from other monoterpene physico-chemical characteristics. H(pc) was strongly correlated with monoterpene saturated vapor pressure (P(v)), and for lipophilic monoterpenes, deltaH(vol) scaled positively with the enthalpy of vaporization that characterizes the temperature dependence of P(v) Thus, P(v) versus temperature relations may be employed to derive the temperature relations of H(pc) for these monoterpenes. These data collectively indicate that monoterpene differences in H(pc) and K(OW) temperature relations can importantly modify monoterpene emissions from and deposition on plant leaves.