Gary W. vanLoon

REMOVAL OF PHOSPHORUS AND ORGANIC MATTER REMOVAL BY ALUM DURING WASTEWATER TREATMENT

Abstract Ferron reagent and FTIR spectroscopy were used for the identification and characterization of the aluminum species formed during dephosphorization of simulated wastewater with and without organic matter. Evidence from FTIR spectroscopy showed the formation of aluminum hydroxyphosphate, hydroxy-Al–tannate and aluminum complexes containing both phosphorus and tannic acid. The surface reactivity of the solid products is proportional to the rate of reaction with ferron. The measured reactivities indicate that aluminum solid species with different surface properties were formed depending on solution components and method of precipitation. Tannic acid was found to inhibit phosphorus removal and the extent of inhibition increased with increasing concentration. When prehydrolyzed aluminum is exposed to tannic acid, the organic matter forms a coating on the surface of the inorganic solid during the aging process. Coprecipitation of aluminum, phosphate and tannic acid, which is synonymous with the addition of alum before or in the aerator, produces some soluble complex and some hydroxy-Al–phosphate–tannate complex, in the form of solid with very small particle size. This system gives high residual aluminum. The results suggest that it is advantageous to add at least a portion of the alum at the exit of the aerator. This enhances phosphorus removal by coprecipitation under conditions where the concentration of organic matter is relatively low and enhances removal of organic matter by postprecipitation onto the recycled sludge in the aerator.

Spectrophotometric methods to determine carbohydrates in soil

Abstract Two common spectrophotometric procedures for determining neutral carbohydrates—the phenol-sulfuric acid and anthrone methods were evaluated for soil analysis. The phenol-sulfuric acid procedure gives results comparable to those obtained by gas-liquid chromatography, and is applicable to a variety of soil types. Prior removal of interfering substances by anion and cation exchange is required. Glucose is recommended as the spectrophotometric reference standard. The anthrone method is not satisfactory under the conditions employed.

The determination of trace metals in cladophora glomerata—c. glomerata as a potential biological monitor

Abstract A differential pulse anodic stripping voltammetry method has been developed for the determination of Zn, Cd, Pb and Cu in Cladophora glomerata. The method has been applied to samples taken in August from a remote island in Lake Ontario (Main Duck) and a shore site near Kingston, Ontario (Deadman Bay). Trace metal contents and concentration factors (CF) for the two samples are: Zn Cd Pb Cu Deadman Bay 23.7 3.9 9.5 7.2 μ/g CF/103 2.9 49 16 2.2 Main Duck 8.2 1.4 12.2 6.4 μg/g CF/103 1.0 18 20 1.9 The concentration factors are the ratio of metal content in the Cladophora (μg/g) to the best value for the metal content of filtered Lake Ontario water (μg/ml); the factors range from 1.0 × 103 to 49 × 103 for the samples and elements studied. It is postulated that C. glomerata can act as a biological monitor, concentrating the trace metals present in the aqueous environment with a reasonably constant CF for each element.

Studies on redistribution during the analytical fractionation of metals in sediments

Abstract This paper examines a commonly used procedure for fractionation of metals in sediments, in order to determine whether redistribution of elements from one phase to another occurs during the extraction steps. Pure synthetic phases were added to portions of the sediments in order to provide fresh unoccupied sites for retention of any metals released during extraction. The spiked sediments along with an unaltered sample were subjected to the fractionation procedure and results compared. No redistribution occurred for cadmium, copper or nickel. Some limited redistribution to oxide and organic phases was observed for chromium, lead and zinc. A large shift of manganese from the exchange complex to other phases was found for all samples. It is concluded that some redistribution does occur during the procedure and it would be difficult to quantify the extent. However, for most elements redistribution may not be sufficiently large to invalidate the method.

Characterization of amorphous aluminum hydroxide by the ferron method.

Characterization by the ferron method of the solid formed during hydrolysis of aqueous aluminum(III), under conditions of water and wastewater treatment, is the focus of the present study. It has been found that the rate of reaction (later referred to as aluminum reactivity) between freshly precipitated amorphous aluminum hydroxide and the reagent containing a reduced form of ferron may be used to characterize the precipitate. With increasing age between 1 min and 45 d, the reactivity of aluminum in the precipitate was found to steadily decrease. For example, a t 50 value (indicating the time for 50% recovery of the added aluminum) for a 1-min aged aluminum hydroxide was found to be near 10 min, while for the 10 000-min aged sample the t 50 value was near 100 min

Effects of raw water conditions on solution-state aluminum speciation during coagulant dilution.

The speciation of aluminum in solutions of alum and various prehydrolyzed, aluminum-based water treatment coagulants was investigated by 27Al NMR at 5 degrees C and 25 degrees C. Alum solutions were seen to contain only mononuclear species including an AlSO4(+) complex, while the prehydrolyzed coagulant solutions contained polynuclear aluminum species, as well. The relative proportions of both polynuclear species and AlSO4(+) complex decreased in cold water. The presence of organic matter had little effect on the speciation of aluminum in diluted alum, but markedly reduced the relative proportion of the tridecamer species in the prehydrolyzed coagulant solutions. The relationship between Al speciation in the coagulants and organic matter removal during jar tests was considered, and the possible role of sulfate in both the formation of the tridecamer species and the effect of organic matter on coagulation efficiency was discussed.

Determination of chloride, nitrate, sulphate and total sulphur in environmental samples by single-column ion chromatography

The analytical performance characteristics of a single-column ion chromatography system are reported. The data were obtained by using conductivity detection as well as by an indirect ultraviolet technique. The method has been applied to the determination of Cl(-), NO(3)(-) and SO(4)(2-) in samples of rain, sewer water, and soil-pore water. Also described are two methods which allow ion Chromatographic analysis of CaS0(4)-extractable nitrate in soils, and total sulphur in soils, marine sediments and plant tissue.

Emerging health risks associated with modern agriculture practices: a comprehensive study in India.

In order to enhance food production, India has adopted modern agriculture practices and achieved noteworthy success. This achievement was essentially the result of a paradigm shift in agriculture that included high inputs of agrochemicals, water, and widespread practice of monoculture, as well as bureaucratic changes that promoted these changes. There are very few comprehensive analyses of potential adverse health outcomes that may be related to these changes. The objective of this study is to identify health risks associated with modern agricultural practices in the southern Indian state of Karnataka. This study aims to compare high-input and low-input agricultural practices and the consequences for health of people in these communities. The fieldwork was conducted from May to August, 2009 and included a survey carried out in six villages. Data were collected by in-depth personal interviews among 240 households and key informants, field observations, laboratory analyses, and data from secondary sources. The study identified four major visible impacts: occupational hazards, vector borne diseases, changing nutritional status, and inequity in development. In the high-input area, mechanization has resulted in more occurrences of serious accidents and injuries. Ecological changes due to rice cultivation in this area have further augmented mosquito breeding, and there has been a surge in the incidence of Japanese encephalitis and malaria. The traditional coarse cereals (complex carbohydrates, high protein) have been replaced by mill-polished rice (simple carbohydrate, low protein). The prevalence of overweight (BMI>25) has emerged as a new public health challenge, and this is most evident in large-landholding households, especially in the high-input agriculture areas. In all agro-ecological areas, it was observed that women faced a greater risk of both extremes of under-nutrition and being overweight. Output-driven and market-oriented modern agricultural practices have changed the ecology and disease pattern in this area in India, and our survey indicated significant health effects associated with these changes. There is a need for more extensive epidemiological studies in order to know the full impact on diseases and to understand the complex causal relationships.

Voltammetric Reduction of Nickel and Cobalt Dimethylglyoximate

The determination of cobalt and nickel in aqueous solutions by stripping voltammetry after adsorptive preconcentration is an established procedure. The method is highly sensitive, but there is some controversy concerning the reasons for the excellent sensitivity. Using a variety of voltammetric techniques, we have determined that the reduction of nickel dimethylglyoximate in an ammonia buffer is consistent with an overall process involving 16 or possibly 18 electrons. This hypothesis is confirmed by independently measuring the total quantity of metal adsorptively deposited on the mercury electrode and comparing the amount with the quantity of electricity required for its reduction.

Agriculture in Uttarakhand, India—Biodiversity, Nutrition, and Livelihoods

This study investigates food production and agrobiodiversity in the Tarikhet and Ukhimath blocks in Uttarakhand, India, located in the middle ranges of the Himalayas. On the small patches of terraced land available to the average household in these areas, the cultivation of a wide range of traditional and high-yielding varieties of grains, legumes, vegetables, and fruits is a positive feature in terms of sustainability. Some villages also supplement plant-based food production and income by incorporating animal husbandry into the overall agroecosystem. It was found, however, that the output of the average farm provides only about half of the household energy requirements, forcing most families to resort to off-farm activities to support a large proportion of their food and other requirements. There is therefore a need to develop policies that will continue to support the rich agrobiodiversity of these areas, while providing for the nutritional and economic needs of the population.