Field demonstration of the combined effects of absorption and evapotranspiration on septic system drainfield capacity.

Drainfields for disposal of septic tank effluents are typically designed by considering the loss of water by either upward evapotranspiration into the atmosphere or lateral and downward absorption into the adjacent soil. While this approach is appropriate for evapotranspiration systems, absorption systems allow water loss by both mechanisms. It was proposed that, in areas where high evapotranspiration rates coincide with permeable soils, drainfield sizes could be substantially reduced by accounting for both mechanisms. A two-year field demonstration was conducted to determine appropriate design criteria for areas typical of the Texas High Plains. The study consisted of evaluating the long-term acceptance rates for three different drainfield configurations: evapotranspiration only, absorption only, and combined conditions. A second field demonstration repeated the experiments for additional observation of the combined evapotranspiration and absorption and achieved similar results as the first study. The field tests indicated that the current design loading criteria may be increased by at least a factor of two for the Texas High Plains region and other Texas areas with similar soil composition and evapotranspiration rates, while still retaining a factor of safety of two.     

RATIONAL INDUSTRIAL WATER REUSE RATIOS1

ABSTRACT: This work begins by defining rational water use, and then discusses important factors that most strongly influence it. A general model is then developed to enable factories to quantify the ratio of rational industrial water reuse based on the least cost method. The model is established to minimize the cost of water with reference to gross water use and three subsystems ‐ the intake, reuse, and discharge of industrial water. Discharge cost is determined using data from a 1997 survey of 38 factories, and reuse costs are ranked and expressed by a step function. The model is verified using data from a typical semiconductor factory in northern Taiwan's Hsinchu Science Based Industrial Park, whose effective rational water reuse ratio is about 38 percent. A sensitivity analysis shows that improving water reuse technology is the most important factor in determining the rational water reuse ratio, and the price of water is the second most important. When water costs over NT$30 (New Taiwan Dollar, US$1 = NT$34) per cubic meter, increasing reuse becomes significant. The model provides a step towards the scientific management of industrial water.     

Determination of Toxic Pollutants in Water Using A Marine Phytoplankton Dunaliella Bioculata and Doppler Laser Velocimetry

This paper reports an experimental study of the response of the unicellular flagellated algae Dunaliella bioculata to toxic pollutants in water using the 'Doppler laser velocimetry' method. the response to toxic pollutants was encouraging and indicates that Dunaliella bioculata is a good biological model for the detection of toxic pollutants in water.     

Germination,Growth, and Nodulation of Sesbania rostrata Grown in Pb/Zn Mine Tailings

Sesbania rostrata in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was 3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant.     

Rational pricing of groundwater with a growing population

When population is increasing, characterizing the optimal water consumption path is complicated by the fact that the underlying dynamics of the water stock is contingent on the level of the stock itself. We propose a method of constructing the optimal path in this case. Since population is increasing, the optimal consumption path may involve refraining at times from consuming the totality of the surface water flow in order to restock in groundwater for future consumption. The aquifer then serves as a means to achieve welfare increasing intertemporal transfers of surface water. Therefore the aquifer itself, as distinct from the stock of water it serves to store, may have value and the marginal valuation of water when groundwater stocks are being drawn upon should, for this reason, differ at times from the marginal valuation of water when it is drawn strictly from surface water.     

滇池水华蓝藻干粉制剂的生物脱毒实验

滇池属长江流域的一个内陆湖泊，近年来水体富营养化日益严重，每年夏季都出现大面积的水华。由品种单一，主要为蓝藻门，其中微囊藻是优势种，产生的微囊藻毒素具有很强的毒性。本实验以富营养化湖湖滇池中的水华蓝藻作为主要原料，将其制成干粉后，利用双协菌株在28－32℃条件下对其进行固态发酵，培养基质初始水份为65％。发酵培养2d后，培养基质中微囊藻毒素含量明显降低，6d后，基质中微囊藻毒素含量未检出（最低浓度检测限1μg/mg）。同时对实验所获得时间序列进行动力学研究，结果表明利用双协菌降解微囊藻毒毒的反应为准一级动力学反应。     

AN LP-10 MODEL FOR COORDINATING MULTI-GROUP INPUTS IN RESOURCE PLANNING1

ABSTRACT A model for guiding public as well as multi-discipline inputs about the development of water and related natural resources has been developed. Optimal location of economic activities can be achieved by iterative use of the model. An example illustrating the manner the model can be used is included in the paper.     

Optimal design for sustainable development of a material recovery facility in a fast-growing urban setting

Installing material recovery facilities (MRFs) in a solid waste management system could be a feasible alternative to achieve sustainable development goals in urban areas if current household and curbside recycling cannot prove successful in the long run. This paper addresses the optimal site selection and capacity planning for a MRF in conjunction with an optimal shipping strategy of solid waste streams in a multi-district urban region. Screening of material recovery and disposal capacity alternatives can be achieved in terms of economic feasibility, technology limitation, recycling potential, and site availability. The optimization objectives include economic impacts characterized by recycling income and cost components for waste management, while the constraint set consists of mass balance, capacity limitation, recycling limitation, scale economy, conditionality, and relevant screening constraints. A case study for the City of San Antonio, Texas (USA) presents a vivid example where scenario planning demonstrates the robustness and flexibility of this modeling analysis. It proves especially useful when determining MRF ownership structure. Each scenario experiences two case settings: (1) two MRF sites are proposed for selection and (2) a single MRF site is sought. Cost analysis confirms processing fees are not the driving force in the City's operation, but rather shipping cost. Sensitivity analysis solidifies the notion that significant public participation plays the most important role in minimizing solid waste management expenses.