Hydroxide Lime Research Articles

Enhanced CH4 Production from Corn Stover by Simultaneous Lime Treatment

Calcium hydroxide (lime) treatment and solid-state anaerobic digestion (SSAD) of corn stover (CS) were carried out simultaneously with different lime doses (0, 2, 3.5, and 5%) and feedstock to seed sludge (F/S) ratios (6, 8, and 10). It was found that the addition of 3.5% lime improved CH4 yield from 118 mL/g VS to 182 mL/g VS (54% increase) during SSAD of CS when F/S ratio was at 6. The improved CH4 production is consistent with increased relative abundance of several microbes that might play important roles in biomass degradation and CH4 generation. At higher F/S ratios (8 and 10), SSADs with different lime doses (0–5%) were all upset with accumulation of volatile fatty acids. Addition of 3.5% lime can obtain a net benefit of $18.4/tonne TS which are 44% of the gross benefit of power production ($41.5/tonne TS) via SSAD of CS and combined heat and power system.

Relative efficiencies of electrolytes in stabilization of an expansive soil

Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have demonstrated that the lime precipitation modifies the expansive soil properties both by lime modification and pozzolanic reactions. However, the independent contributions of either calcium chloride solution or sodium hydroxide solution in stabilizing the expansive soil are not known. Therefore, an attempt is made in the present investigation to examine the relative efficiencies of calcium chloride solution, sodium hydroxide solution and lime precipitation in stabilizing the expansive soil by comparing the physico-chemical and index properties, oedometer swell potentials and unconfined compressive strength of treated specimens. The present investigation also brings out the relative efficiencies of hydrated lime and precipitated lime in stabilizing the expansive soil. The experimental results showed that treating the expansive soils with calcium chloride and sodium hydroxide solutions independently promoted only the short-term reactions whereas the sequentially treating the expansive soil with calcium chloride and sodium hydroxide solutions resulted in the formation of lime precipitation, which could mobilize both short-term lime-modification reactions and long-term soil-lime pozzolanic reactions.

Los materiales alternativos estabilizados y su impacto ambiental

El presente trabajo es resultado de investigaciones desarrolladas a partir de la experimentación de materiales alternativos para la edificación, en especial, relacionado con Bloques de Tierra Comprimida (BTC), que han sido estabilizados con hidróxido de cal y cemento, buscando cumplir con las Normas Mexicanas, en el apartado referente a materiales para uso en mampostería de las edificaciones y así corroborar que estos materiales cumplen con requisitos de calidad, al igual que los materiales convencionales, aunado a la realización del análisis de ciclo de vida (ACV) en dos poblaciones de BTC’s estabilizados con cementantes, buscando determinar su impacto ambiental y finalmente poder contrastarlos con las bases de datos existentes de materiales convencionales.

Experimental investigation on the chemical and physical properties of activated glass powder pastes

This paper reports on the results of an investigation carried out to examine the ability of fine glass to be used in the concrete industry. The pozzolanicity of the glass powder (GP) hydration with and without calcium hydroxide (CH) (lime) is assessed using different methods. A comprehensive experimental programme is carried out to investigate the chemical and physical properties of the hydrated activated GP with CH, as a cement hydration product, on the microstructural level. The experimental work focuses on the degree of hydration, pH and the alkalinity nature of the pore solution to evaluate the performance of the GP when it reacts with the CH. A flame emission spectroscopy test was used to quantify the alkali release from the GP as well as determining the rate of alkali release with time. It was found that the GP releases a small fraction of sodium ions into the solution. Test results showed that the finely ground GPs exhibited very high pozzolanic activity. It was observed that the GP–lime pastes show high non-evaporable water content. Moreover, the best performance of the GP reactivity can be obtained in the range of 10·5 < pH < 11·5 depending on the CH/GP ratio. According to the scanning electron microscope analysis, the gel product of the GP hydration precipitates on the surface of the large particle of the GP, at which the very small micro particles and the outer layer of the large GP particles react with CH.

Chemical precipitation of aerobically treated olive mill wastewater

The major water pollution problem facing the Mediterranean region is because of the olive mill wastewater (OMW), produced after the extraction of olive oil. Laboratory scale experiments were performed to determine the effectiveness of chemical treatment by the use of cationic polyacrylamide flocculant on raw olive mill effluent, coagulant aluminium sulphate(alum), precipitant calcium hydroxide (lime) blended with cationic polyacrylamide on aerobically treated whey or pig slurry coalesced with OMW. The results show that the chemical treatment is useful for colour reduction by 31.6-74.1%, COD reduction by 15.5-45%, total solids by 6-42%, phenolic compounds by 52.3% and lipids by 69.9%.

Cleaning of gases formed during thermal detoxication of polluting substances

A scheme is developed for the moist cleaning of gases in a system consisting of an oxidizing reactor and bag filter. A suspension of calcium hydroxide (lime) is used as a sorbent. Reactions that occurred during absorption are cited. Advantages of the moist method of removing acidic components and suspended solid particles from flue gases are described.

Long-term effects of preplant liming on apple trees and soil cation levels

Nine years after liming a sandy loam orchard soil to pH 6.0 with calcium hydroxide or dolomitic lime, pH and extractable Ca and Mg were still higher where limed than where unlimed. However, pH had decreased below 5.0 in the limed and N-fertilized plots. Delicious (Malus domestica Borkh.) apple tree nutrition benefited from the two soil amendments. Leaf Mg was increased by dolomite. Leaf Ca was increased by calcium hydroxide. Leaf Mn, although highest in unlimed soils, increased over time for both limed and unlimed soil. Key words: Apple, lime application, reacidification

Viruses in sewage: effect of phosphate removal with calcium hydroxide (lime)

During calcium hydroxide (lime) treatment (pH 9.6 to 10.5) of wastewaters for phosphate removal there was also a two-log removal of added poliovirus (type I, Sabin) from effluents. A similar virus reduction was seen in the sludge generated in these experiments. However, in view of the limitations of techniques for virus recovery from sludge, only a small portion of the infectious virus present in lime sludge may have been detected. Storage of lime sludge at 28 degrees C for up to 48 h produced no appreciable reduction in the virus titre. Five sets of field samples of sewage, effluents, and sludge from a sewage treatment plant (Kemptville, Ont.) which utilizes lime for phosphate removal were also examined for indigenous viruses being BS-C-1 cells. All of the sample of lime sludge and 80% of the samples of both sewage and lime-treated effluent revealed virus; after chlorination only 20% of the lime-treated effluent samples were positive for virus. In contrast, in an earlier study with essentially the same experimental set up, 76% of the sample of chlorinated primary effluent were found to contain virus. Because of the easily detectable quantities of infectious virus in lime sludge and due to the lack of virus inactivation during storage of such sludge, caution must be exercised in its handling and disposal.