INDUSTRIAL WASTEWATER CONTROL IN CHINESE CITIES: DETERMINANTS OF SUCCESS IN ENVIRONMENTAL POLICY

The research reported in this paper has three objectives: (1) to examine trends in Chinese industrial wastewater pollution and to describe policies developed to control this pollution; (2) to analyze relationships between the degree of industrial wastewater pollution control and the economic, demographic, and organizational characteristics of major Chinese cities; and (3) to identify factors that determine the success of the government's efforts to control industrial wastewater pollution. The study specifies and econometrically estimates a system of pollution control equations based on a unique data set for 82 Chinese cities from 1985 to 1990. Results demonstrate that the structure of enterprise ownership and investment in environmental management capacity are associated with increases in the effectiveness of wastewater pollution control. The Discharge Permit System, one of China's main strategies for urban environmental protection, appears to have been moderately successful in increasing wastewater treatment, but it has not encouraged enterprise managers to adopt less-polluting production technology.     

Analysis of phenylurea herbicides by formation of methylated derivatives in the gas-liquid chromatograph using trimethylanilinium hydroxide

Summary When phenylurea herbicides are injected into the gas-liquid chromatograph together with trimethylanilinium hydroxide they react to yield methylated derivatives having good gas chromatographic properties. This derivatization technique allows rapid qualitative and quantitative chromatography of these pesticides. The N-methylated standards obtained were identified by spectroscopic techniques.

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Gas-chromatographische Bestimmung von Phenylharnstoffherbiciden durch Umsetzung mit Trimethylphenylammoniumhydroxiden zu Methylderivaten

Zusammenfassung Vorbereitete Mischungen von Phenylharnstoffherbiciden und Trimethylphenylammoniumhydroxiden wurden nach der Einspritzung zu Methylderivaten umgesetzt. Diese Verbindungen weisen gute GLC-Trennungen auf. Das Verfahren eignet sich für die schnelle qualitative und quantitative Bestimmung der untersuchten Verbindungsreihen. Die dazu vorbereiteten Eichsubstanzen wurden mit Hilfe spektroskopischer Methoden identifiziert.

     

Burnett—isochoric P—V—T measurements of a nominal 20 mol% hydrogen—80 mol% methane mixture at elevated temperatures and pressures

A new apparatus is described which has been developed to measure P—V—T relations for hydrogen—hdyrocarbon systems at elevated temperatures and pressures. The principal components are three heavy-walled spherical pressure cells with the same outer/internal diameter ratio, a fully submerged differential pressure cell, and measuring equipment including calibrated piston guages and a platinum resistance thermometer. This apparatus was used to measure densities of a 20.05±0.05 mol% hydrogen?79.95±0.05 mol% methane mixture from 273.15 to 600 K and pressures to 72 MPa. Two Burnett isotherms at 273.15 K established fluid densities without direct measurement of either mass or volume. Eight isochores, ranging in density from 1.62 to 14.91 mol dm^?3, were anchored to the Burnett isotherms at 273.15 K where their densities were firmly established. An analytic equation for the thermodynamic surface has been fitted to the resulting P—V—T data, giving a 0.01% root mean square deviation of calculated compressibility factors from experimental results.     

A computationally efficient modification of mixed finite element methods for flow problems with full transmissivity tensors

The mixed finite element method for approximately solving flow equations in porous media has received a good deal of attention in the literature. The main idea is to solve for the head/pressure and fluid velocity (Darcy velocity) simultaneously to obtain a higher order approximation of the fluid velocity. In the case of a diagonal transmissivity tensor the algebraic equations resulting from the discretization can be reduced to a system of algebraic equations for the head/pressure variable alone. This reduction results in a smaller number of unknows to be solved for in an iterative method such as preconditioned conjugate gradient method. The fluid velocity is then obtained from an algebraic relationship. In the case of full transmissivity tensor, the algebraic reduction is more difficult. This paper investigates some algorithms resulting from the modification of the mixed finite element that take advantage of the mixed finite element method for the diagonal tensor case. The resulting schemes are more efficient implementations that maintain the same order of accuracy as the original schemes. © 1993 John Wiley & Sons, Inc.     

Modelling of the pore size distribution of ultrafiltration membranes

A dilute aqueous solution of polydisperse neutral dextrans was used to determine the sieving properties (flux and rejection) of porous polyacrylonitrile membranes. Gel ermeation chromatography was used to measure the solute mole and concentration in the permeate. From these data, rejection coefficients were calculated as a function of solute molecular size. A mathematical model was then developed to relate the flux and solute rejection to pore size distribution and the total number of pores, based upon the assumption that solute rejection was the result of purely geometric considerations. As a first approximation, a solute molecule was considered either too large to enter a membrane pore, or if it entered, its concentration in the permeate from that pore, as well as the solvent flux through the pore, were not affected. This model also considered the effects of steric hindrance and hydrodynamic lag on the convection of solute through a membrane. The shape and sharpness of pore size distributions were found to be useful in comparisons of ultrafiltration membranes.