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PubMed2002

[Effect of low molecular weight organic acids on inorganic phosphorus transformation in red soil and its acidity].

Red soil samples collected from southern Hubei province and northern Jiangxi province were tested to analyze their inorganic phosphorus fractions, pH and active aluminum after incubated with added various organic acids. The results indicated that application of organic acids increased the content of Ca2-P in both red soils, in the order of citric acid > malic acid > succinic acid > acetic acid, did not affect the contents of Ca8-P and Ca10-P, but usually reduced Fe-P, Al-P and O-P. The pH values of the soils treated by organic acids, except for acetic acid, were reduced by 0.65-1.96, compared with the control. Soil active Al extracted with 0.02 mol.L-1 CaCl2 in treatments with citric, malic and succinic acid was 5.7-51.3 times as the control, and Al extracted with 1 mol.L-1 KCl also increased 4.0-67.3 times. However, acetic acid had little influence on active soil Al. It was concluded that in red soils, organic acid could improve phosphorus availability, but enhance the soil toxicity caused by active Al.

Acids↗
PubMed2002

Polymer conditioning of alum sludge and discrepancies between estimates of the optimum dosage.

The paper outlines the effects of polymer conditioning on alum sludge properties, such as floc size, density, fractal dimension (DF) and rheological properties. Experimental results demonstrate that polymer conditioning of alum sludge leads to: larger floc size with a plateau reached in higher doses; higher densities associated with higher doses; increased degree of compactness; and an initial decrease followed by an increase of supernatant viscosity with continued increase in polymer dose. The secondary focus of this paper dwells on a comparison of the estimates of optimum dose using different criteria that emanate from established dewatering tests such as CST, SRF, liquid phase viscosity and modified SRF as well as a simple settlement test in terms of CML30. Alum sludge was derived from a water works treating coloured, low-turbidity raw waters.

Alum Compounds↗
PubMed1976

Treatment of allergy to house dust with pyridine-extracted alum-precipitated extracts of the house dust mite.

Two preliminary trials in which patients with respiratory allergy to the house dust mite were treated with pyridine-extracted alum-precipitated extracts of house dust mites are described. In the first, using an extract of D. farinae, twenty-two of twenty-eight asthmatic patients improved. In the second, using an extract of D. pteronyssinus, fifteen of eighteen asthmatic patients improved.

Alum Compounds↗
PubMed2002

[Preparation of PSAS and its application in HAB prevention].

In order to obtain optimum PSAS (Polysilicate-aluminium sulfate) preparation conditions for removing HAB organisms, the 3-factor and 3-level orthogonal test was devised. Concentration of SiO2, Al3+/SiO2 molar ratio and pH were chosen as the three chief factors in PSAS preparation. The experimental results showed that the optimum preparation condition for various HAB organisms was different, and according to practical experimental operation, the appropriate preparation condition was considered as: concentration of SiO2 = 2%, molar ratio of Al3+/SiO2 = 1, and pH = 4. In addition, the coagulation efficiencies of PSAS on various HAB organisms were studied and compared with classical inorganic flocculant AS (Aluminium sulfate). The results indicated that the removal rates of PSAS were much higher than those of AS, and the dosages of PSAS were 30-40% lower than those of AS when they achieved the same removal rates. On the other hand, the anti-coagulation ability of HAB organisms varied with algal species, which was related to different physiological and ecological features of various algal cells.

Alum Compounds↗
PubMed2003

Optimum physical-chemical pre-treatment of copper damascene wastewater.

Chemical and mechanical polishing (CMP) of copper damascene circuits will typically produce copper levels in excess of regulatory limits in wastewater with a unique process chemistry, including high solids. Physical-chemical methods were investigated to determine the optimum treatment depending upon pre-treatment and/or water reuse requirements. Jar test studies revealed that an alum dose of 150-200 mg/L together with anionic polymer aid provided a good removal of turbidity. If the treatment objective is simply solids and copper reduction for discharge to a sewer system, then solids removal can combined with precipitation of copper hydroxide for relatively inexpensive pre-treatment. The presence of peroxide from the process solution, however, may make it difficult to achieve copper values below 5 mg/L, depending on the associated process conditions. If the objective is to remove solids and recover copper, which may also allow recovery of water for reuse, then solids removal by alum and polymer can be followed by ion exchange by a strong acid cation resin. As with precipitation, however, effective copper removal by ion exchange requires pre-treatment of peroxide by chemical reduction. The exchange of dissolved aluminum also reduces the capacity of the resin for copper.

Alum Compounds↗