Lime Dosage Research Articles

AN EXPERIMENTAL FACTORIAL DESIGN FOR ASR MITIGATION WITH FLY ASH

Use of fly ash by percent replacement of cement by weight is considered as one of the most economical and effective method for mitigating Alkali-silica reaction (ASR) related distress in the concrete. Fly ash reduces the pore solution alkalinity through increasing the alkali binding capacity of the cement hydrates and through pozzolanic reaction. However, Fly ash is proven to be somewhat variable in its effectiveness on inhibiting alkali-silica reactivity, principally because its composition depends on the coal properties from which it is derived. Typically Class C fly ashes are not as efficient as Class F ashes due to their higher calcium oxide content. Also, it is not established if the dosage of fly ash is more influential than type of fly ash and vice versa. Therefore, in the field, for a certain job mixture, the prediction of mitigation effect of a certain type and dosage of fly ash is difficult. This research aims to correctly predict the effectiveness of fly ash mitigation, to find out the most influential factor and interaction effects between factors. A statistical model, of two-level design with 3 factors, was developed based on three main factors: fly ash lime content, dosage and soak solution alkalinity. The statistical model was verified with additional experimental results with random fly ash-lime content and different dosages; which matched very well with the model predictions. Therefore, such model(s) could be applied in practice with the availability of larger database. Also, another finding of this research is that, the lime content of the fly ash is the most significant factor followed by the dosage level.

Pre-separation of ammonium content during high solid thermal-alkaline pretreatment to mitigate ammonia inhibition: Kinetics and feasibility analysis

The feasibility of ammonia pre-separation during the thermal-alkaline pretreatment (TAP) of waste activated sludge was evaluated to mitigate ammonia inhibition during high solid anaerobic digestion (HSAD). The results showed that the TAP increased the organics hydrolysis rate as much as 77% compared to the thermal hydrolysis pretreatment (THP). The production and separation of the ammonia during the TAP exhibited a linear relationship with the hydrolysis of organics and the Emerson model. The pre-separation ratio of the free ammonia nitrogen exceeded 98.00% at a lime dosage exceeding 0.021 g CaO/g TS. However, the separation ratio of the total ammonia nitrogen (TAN) was hindered by its production ratio. Compared to the THP, the TAP increased the methane production rate under similar production yield. A mass flow analysis indicated that the TAP-HSAD process reduced the volume of the digester compared to the THP-HSAD process and the recirculated HSAD-TAP process recovered 45% of the nitrogen in the waste activated sludge.

Phosphorus Loss Mitigation in Leachate and Surface Runoff from Clay Loam Soil Using Four Lime-Based Materials

The increased eutrophication phenomenon in Quebec lakes calls for an urgent phosphorus-reducing strategy to meet the Quebec water quality standard of 0.03 mg L−1 for phosphorus (P). The objective of this research was to evaluate the application of four lime-based products in reducing P losses through subsurface leachate and surface runoff and to determine their optimum application. Two sets of experiments were conducted: laboratory leaching study and runoff study with a rainfall simulator, using a clay loam soil collected from the Pike river watershed. The former followed a flow method with a full factorial design in three replicates. Soil columns were amended with different application dosages of lime ranging from 0 to 2% by soil weight. The results showed that all four lime-based products could be promising amendments in reducing P losses in the leachate. According to statistical analysis of ANOVA, high calcium hydrated lime and lime kiln dust #2 were found to be the most effective with an optimum application dosage of 1% while reducing total dissolved phosphorus concentrations in leachate from 0.057 to 0.009 and 0.023 mg L−1, respectively. For the runoff study, a rainfall simulator with a maximum rainfall intensity of 2 cm h−1 was built. High calcium hydrated lime and lime kiln dust #2 were able to reduce total dissolved phosphorus to 0.034 and 0.037 mg L−1, respectively. However, particulate phosphorus was significantly increased at the studied application rate. The results from this study can offer a promising measure in reducing total dissolved phosphorus in groundwater while providing a solution to the existing environment issue of eutrophication.

Strength properties of Bayer red mud stabilized by lime-fly ash using orthogonal experiments

Bayer red mud (RM) was produced from aluminum ore according to Bayer process. In order to study the feasibility of stabilized Bayer RM for use in road construction, strength properties of RM stabilized by lime-fly ash using orthogonal experimental method were evaluated. In test design, the normalized orthogonal table of L9 (34) was adopted. The influence of ratio of lime-ash, the dosage of lime and fly ash, and the type of Bayer RM (Two kinds of Bayer RM from different producers) on the unconfined compressive strengths (UCS) of 7-day and 28-day curing age were studied. The experimental results showed that these factors significantly influenced the UCS. The principal factors influencing 7-day UCS was ratio of lime-ash, followed by chemical compositions of Bayer RM and the dosage of lime and fly ash in last. The principal influencing factor of 28-day UCS was chemical compositions of RM, followed by ratio of lime-ash and the dosage of lime and fly ash in last. Then the optimum proportion for the UCS was determined through the orthogonal analysis. The X-ray fluorescence (XRF) showed that chemical compositions and contents of two types of RM were significantly different in iron, silicon and calcium. The microscopic analysis of the raw material and stabilized material employed X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) showed that C3A(Ca3Al2O6), C2S, and calcium carbonate increased under the optimal conditions of lime-fly ash stabilization, and hydrated silica aluminate and CSH were gradually generated. The stabilization mechanism of Bayer RM by lime-fly ash is related to hydration like aluminate cement. There is no essential difference in reaction mechanism for two kinds of Bayer RM and the difference in the strength properties is essentially originates from the active material content.

PERTUMBUHAN BIBIT AREN (Arenga pinnata Merr) PADA MEDIA TANAH ULTISOL DIPERSEMAIAN

Arenga pinnata Merr is a multipurpose trees species that has long been known to produce industrial materials. Based on the utilization of Arenga pinnata Merr is not only limited to the food alone but also used as a raw material for industrial and land conservation. Arenga pinnata Merr has prospect good to be developed in the tree crop plantations. Arenga pinnata Merr cultivation activities require good quality seeds. Currently Arenga pinnata Merr still growing naturally in the forest. Exploitation by the farmers during this time in the form of Arenga pinnata Merr exploitation of the forest without cultivation. There are concerns Arenga pinnata Merr that grows in nature will be destroyed. The purpose of this research to study the effect of a doses of organic fertilizer and dolomite lime on the growth of Arenga pinnata Merr in the nursery. The study used an experimental method with a completely randomized design factorial models. The study consisted of two factors: factors of organic fertilizer and lime dolomite with five repetitions with a number of plant samples as many as 100 plants. The measured parameters include length midrib, stem diameter and stem height were analyzed using SAS IX. The research proves that organic fertilizer dose of 300 g and 35 g dolomite lime can increase the growth of palm in the nursery. Keywords: Arenga pinnata Merr, fertilizer, lime, organic.

Correlation of Surface Adsorption and Oxidation with a Floatability Difference of Galena and Pyrite in High-Alkaline Lime Systems.

When it comes to Pb-Zn ores with high amounts of pyrite, the major problem encountered is the low separation efficiency between galena and pyrite. By virtue of high dosage of lime and collector sodium diethyl dithiocarbamate (DDTC), pyrite and zinc minerals are depressed, allowing the galena to be floated. However, there have been significant conflicting reports on the flotation behavior of galena at high pH. In this context, correlation of the surface adsorption and oxidation with the floatability difference of galena and pyrite in high-alkaline lime systems would be a key issue for process optimization. Captive bubble contact angle measurements were performed on freshly polished mineral surfaces in situ exposed to lime solutions of varying pH as a function of immersion time. Furthermore, single mineral microflotation tests were conducted. Both tests indicated that the degree of hydrophobicity on the surfaces of galena and pyrite increased in the presence of DDTC at natural or mild pulp pH. While in a saturated lime solution, at pH 12.5, DDTC only worked for galena, but not for pyrite. Surface chemistry analysis by time-of-flight secondary ion mass spectrometry (Tof-SIMS) confirmed the preference of DDTC on the galena surface at pH 12.5, which contributed to a merit recovery. Further important evidence through measurements of Tof-SIMS, ion chromatography, and high-performance liquid chromatography indicated that in high-alkaline lime systems, the merit floatability of galena could exclude the insignificant contribution of elemental sulfur (S8) and was dominantly attributed by the strong adsorption of DDTC. In contrast, the poor flotation response of pyrite at high pH was due to the prevailing adsorption of CaOH+ species. This study provides an important surface chemistry evidence for a better understanding of the mechanism on the better selectivity in the galena-pyrite separation adopting high-alkaline lime systems.

One-step synthesis of a β-cyclodextrin derivative and its performance for the removal of Pb(II) from aqueous solutions

A new multifunctional β-cyclodextrin-sodium xanthogenate (β-CDX) was successfully synthesized by a one-step process and applied to remove Pb(II) from aqueous solutions. The characteristics and chelation mechanisms of β-CDX were investigated by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy, and the influences of various operating parameters such as pH (lime dosage), the order of the additions, β-CDX dosage, and the initial concentration of Pb(II) on the removal capacity of β-CDX and the characteristics of the products were systematically evaluated. The results demonstrated that the optimal removal effect for Pb(II) was achieved when β-CDX was used rather than using lime alone. In addition, it was more effective to add β-CDX to the working solutions prior to adding the lime than adding β-CDX after the lime. The use of 0.05 g/L of β-CDX was effective for the removal of Pb(II) according to the residual concentration when the initial concentration was 100 mg/L at different pH values. The maximum removal rate of the Pb(II) ions was 98% for all initial concentrations and the products were larger (size = 137.9 μm) and looser (Df = 1.73) at an optimum pH range from 9 to 12. The characterization results confirmed that the RC(S)SNa in the β-CDX was the main contributor to the chelation of the Pb(II). These properties of β-CDX make it a promising compound for the treatment of wastewater contaminated by hazardous metal ions.

Biochar improves maize growth by alleviation of nutrient stress in a moderately acidic low-input Nepalese soil

We studied the role of biochar in improving soil fertility for maize production. The effects of biochar on the alleviation of three potential physical-chemical soil limitations for maize growth were investigated, i.e. water stress, nutrient stress and acid stress. Experiments involved soils with two dosages of biochar (0.5% and 2% w:w), as well as ones without biochar, in combination with four different dosages of NPK fertilizer, water and lime. Biochar was produced from the invasive shrubby weed Eupatorium adenophorum using flame curtain kilns. This is the first study to alleviate one by one the water stress, nutrient stress and acid stress in order to investigate the mechanisms of biochar effects on soil fertility.Biochar addition increased soil moisture, potassium (K) and plant available phosphorous (P-AL), which all showed significant positive relationship (p<0.001) with above ground biomass of maize. However, biochar was much more effective at abundant soil watering (+311% biomass) than at water-starved conditions (+67% biomass), indicating that biochar did increase soil moisture, but that this was not the main reason for the positive biomass growth effects. Biochar addition did have a stronger effect under nutrient-stressed conditions (+363%) than under abundant nutrient application (+132%). Biochar amendment increased soil pH, but liming and pH had no effect on maize dry biomass, so acidity stress alleviation was not the mechanism of biochar effects on soil fertility.In conclusion, the alleviation of nutrient stress was the probably the main factor contributing to the increased maize biomass production upon biochar addition to this moderately acidic Inceptisol.

Shearing Performance of Lime‐Reinforced Iron Tailing Powder Based on Energy Dissipation

The resource utilization of iron tailing powder is an effective measure to reduce the risk of tailing stacking. Based on the research findings on lime soil, a method for using lime to strengthen iron tailing powder was proposed. F-s curves and c and φ values of iron tailing powder with 0%, 2%, 4%, 8%, and 10% lime were obtained through direct shear tests. The back propagation (BP) neural network algorithm was used to fit the F-s curve, and the fitting equation that met the accuracy requirement was obtained. Based on the energy dissipation theory, the shear failure energy dissipation of iron tailing powder with different lime doses was achieved in the form of definite integrals under different normal stresses of 100 kPa, 200 kPa, 300 kPa, and 400 kPa, respectively. It was concluded that the addition of lime could increase the shear energy dissipation of iron tailing powder. The shear energy dissipation of iron tailing powder first increased and then decreased with the increase in lime dose. The maximum value was reached with 4% lime, and the energy dissipation increased linearly with increasing normal stress. In this study, the shear performance of lime‐reinforced iron tailing powder was studied through the direct shear test combined with the energy dissipation theory, providing a theoretical basis for the resource utilization of iron tailing powder.

Utilization of Golden Apple Snail (Pomacea canaliculata) Shells as Liming Materials for Pangasius sp Culture in Swamp Fish Pond

Liming ponds is intended to increase swamp soil and water fish ponds pH. The golden apple snail (Pomacea canalicuata) is one kinds of agriculture pest which is potentially used as material of lime. The golden apple snail shells containing CaO (91.62%) and MgO (1.66%). This study aims to determine the best dosage of lime derived from golden apple snail shells to increase the pH of soil and water, as well as the survival and growth rate of catfish fingerlings. This study used Completely Randomized Design (CRD) with 5 treatments (4 treatments of different dosage of lime derived from golden apple snails and 1 treatment using calcite and 3 replications. The treatments used consisted of different dosages of lime : P1) 4 ton/ha; P2) 5 ton/ha; P3) 6 ton/ha; P4) 7 ton/ha and P5) calcite 6 ton/ha equivalent to CaO. The result showed that maximal pH value of P4 (lime derived from P. canaliculata 7 ton/ha) is almost same as pH of P5 (calcite 6 ton/ha) but P4 is faster to reach than that of P5. At the final day of research P4 has no significant different with calcite 6 ton/ha (P5) for alkalinity, fish growth and feed efficiency.

EXTRACTION OF GOLD AND SILVER BY CYANIDATION PROCESS FROM COMPLEX ORE OF SHOUGHUR AREA CHITRAL, KYBER PAKHTUNKHWA

The aim of the research work was to optimize the cyanidation leaching parameters for maximum extraction of gold and silver from complex ore of Shoughur area of district Chitral, Khyber Pakhtunkhwa on laboratory scale testing. The research work was carried out into two parts. In first part the cyanidation parameters like grinding time, dosage of pH, cyanidation time, dosage of sodium cyanide (NaCN) and dosage of lime Ca (OH)2 were optimized. The samples were subjected to differential grinding time varying from 20 to 35 minutes, pH of slurry adjusted from 9 to 11 by adding Ca (OH)2 from 0.5 to 1.5 gm/kg , dosage of NaCN varies from 0.1% to 0.02 % and cyanidation time varies from 0 to 40 hours. The maximum yielded of 71.82 gm/ton of gold grade and silver grade of 34.34 gm/ton was obtained at grinding time of 25 minutes, particle size 63 um, pH 10.40, cyanidation time of 37 hours and at lime dosage of 0.5gm/kg. In the second part the cyanidation process was applied on roasted and un-roasted ore samples. The cyanidation time and grinding time were optimized. The maximum grade of gold 71.82 ppm and silver 25.95 ppm was extracted from roasted ore samples at cyanidation time of 35 hours and grinding time of 30 minutes as compared to unroasted ore samples. It is concluded that cyanidation process on roasted ore samples gives encouraged results as compared to un-roasted ore samples

Growth and Yield Response of Bambara Groundnuts (Vigna subterranea L ) to the Mixed of Peat and Mineral Soil with Several Dosage of Dolomite

Bambara groundnut (Bogor groundnut) was an alternative food crops having high nourishing, better taste and bigger size nut than the soy beans and peanuts. To meet the need for food and industrial needs, the program to increase production of Bogor groundnut was required, one of which is the use of peat as a growing medium using the technology of mixing peat and mineral soil. The research objective was to obtain a mixture of peat with mineral soil and dolomite lime dose suitable for the highest growth and yield of Bogor groundnut. This study was conducted in May 2015-September 2015 in the Greenhouses of Faculty of Agriculture, University of Bengkulu. The experiment was arranged in a completely randomized design (CRD) with two treatment factors and three replications. The first factor was soil mix of peat and mineral soil (G0: 100% peat + 0% mineral soil; G1: 75% peat + 25% mineral soil; G2: 50% peat + 50% mineral soil; G3: 25% peat + 75% mineral soil) and the second factor was the dose of dolomite (D0: without lime dolomite; D1: 3 ton ha-1 and D2: 4 ton ha-1). The results showed that the response of biomass dry-weight to a mixture of peat with mineral soil was influenced by the dose of dolomite, but there was no interaction on other variables. Treatment of a mixture of peat 100% alone was capable of generating the highest number of leaf, biomass fresh- and dry-weight. Bogor groundnut plants showed the same response to the dose variation of dolomite lime.Keywords: Bogor groundnut, peat, mineral, dolomite

Utilization of Anadara granosa as a Liming Materials for Swamp Fish Ponds for Pangasius sp Culture

Availability of water in swamp areas is abandon almost throughout the year, therefore these areas are potential for aquaculture development. However, the characteristics of swamp water is mainly acid water, therefore, it becomes mayor problems in swamp fish culture development. Liming of ponds is intended to increase pH value of soil and water of fish ponds. A. granosa shells is one of domestic waste containing of 61.16% CaO and 21.65% MgO, therefore it can be used as an alternative material for liming of fish ponds. The aims of this research was to evaluate the potency of lime derived from A. granosa shells to raise soil’s and water’s pH, and to evaluate its effect to survival and growth of Pangasius sp. The research was conducted and arranged based upon completely randomized design with five treatments and three replications. The treatments used consisted of different dosages of lime, namely : P1) 1 ton/ha; P2) 2 ton/ha; P3) 3 ton/ha; P4) 4 ton/ha and P5) 5 ton/ha of lime equivalent to CaO. The results showed that both the soil and water reach a neutral pH at a dosage of 2 ton/ha (P2), 3 ton/ha (P3), 4 ton/ha and 5 ton/ha. The dosage of 5 ton/ha (P5) was the best treatments among all treatments, with a highest survival rate (100%), absolute growth of fish lenght (9.35 cm) and weight (40.69 g), as well as feed efficiency (110.97%).

Long-term application of fertilizers on chemical and biological properties of an Alfisol

A long term fertilizer experiment (30 years) at Bengaluru had been started during 1986 with eleven treat-ments and four replications in an Alfisol on finger millet (Elusine coracana) maize (Zea mays) cropping sequence. The results of the ongoing experiment after 27 cycles of finger millet and maize on changes in soil chemical proper-ties revealed that application of inorganics alone resulted in impaired soil fertility status (soil pH, organic carbon con-tent and available nutrients in soil were decreased) over balanced fertilizer application. There was a decline in soil reaction over the initial status and the maximum decrease was observed in 100 % NP (-1.46), 100 % N (-1.20) and other treatments. Application of 100 % NPK+FYM+lime maintained the soil pH (6.2) compared to all the other treat-ments. Organic carbon content of soil in all the treatments was higher (6.46 g kg-1) compared to the initial status; however, maximum increase in organic carbon content was registered on application of NPK+FYM. Application of 10 t ha-1 along with recommended dose of fertilizers and lime was found promising in term of sustaining crop and soil productivity.

Characteristics of Sie Reuboh Supplemented with Different Combinations of Palm Vinegar (Arenga pinnata) and Kaffir Lime Leaves (Citrus hystrix)

This research was aimed to analyze the characteristics of sie reuboh processed with the addition of palm vinegar and kaffir lime leaves with different concentrations to produce sie reuboh with a good quality and to maintain the stability of its quality during storage at room temperature. The research consisted of 2 stages. In the first stage, 4000 g of sie reuboh was treated with different doses of palm vinegar and kaffir lime leaves (0 mL and 0 g, 100 mL and 10 g, 120 mL and 20 g, and 140 mL and 30 g) for microbiological analysis. Sie reuboh with the best result of microbiological analysis was later used in Stage 2 to be stored at room temperature and was analyzed for its physical antioxidant activity, thiobarbituric acid reactive substance (TBARS), and microbiological analysis. The result showed that different levels of palm vinegar and kaffir lime leaves did not significantly affect the aw, pH, yield, and microbiological characteristics of the sie reuboh. Different ratios of palm vinegar and kaffir lime leaves significantly affected (P<0.05) the tenderness of sie reuboh. Sie reuboh without addition of palm vinegar and kaffir lime leaves showed a better tenderness than sie reuboh added with palm vinegar and kaffir lime leaves. The best treatment based on microbiological analysis was shown by treatment of sie reuboh with 120 mL of palm vinegar and 20 g of kaffir lime leaves and this sie reuboh was later used to test the stability of the sie reuboh when it was stored at room temperature. The results showed that sie reuboh produced by addition of 120 mL of palm vinegar and 20 g of kaffir lime leaves demonstrated antioxidant activity for inhibition of free radicals as was indicated by the stability of TBARS value during 9 days of storage at room temperature. This combination of treatment could also effectively stabilize the quality of sie reuboh, as indicated by a proper storability at maximum limit of total plate count and mold growth until 3 days of storage at room temperature.

Physicochemical and Structural Properties of an Oxisol under the Addition of Straw and Lime

Core Ideas Liming represents a common agricultural practice for abating soil acidity. High doses of lime on the Oxisol surface increases the electronegativity of the soil system. High electronegativity increases clay dispersion in the uppermost soil layer. Clay migration led to a series of physical alterations in soil subsurface layers. Overliming can lead to the degradation of highly weathered soil structures. Liming represents a common agricultural practice for abating soil acidity. Nevertheless, elevated amounts of agricultural lime in Oxisols, with or without cultural residue addition, could alter soil physicochemical properties and impact soil structure. In this context, the physical, chemical, and structural behaviors of an Oxisol under the addition of lime and straw were assessed. Lime doses (0, 3.9, 7.8, and 15.6 Mg ha–1) were either applied on the surface or incorporated into the 0‐ to 5‐cm soil layer. Straw applications followed the same procedure with quantities of 0, 4, 12, or 16 Mg ha–1. The effects on the soil profile were evaluated through physicochemical (specific surface area, ζ potential, and pH), physical (density, penetration resistance, water dispersible clay, and total porosity), and micromorphological properties (surface area, volume, connectivity, size, and pore anisotropy) 1 yr after soil incubation in polyvinyl chloride cylinders 30 cm long and 14.5 cm in diameter. Lime application on the surface or into the 0‐ to 5‐cm layer increased soil pH to values above 7.0 and the electronegative potential of soil colloid surface, promoting clay dispersion. Water‐dispersed clay migrated in the soil profile, causing pore obstruction, and higher soil density and penetration resistance. In addition, excessive lime decreased specific surface area, anisotropy degree and the connectivity of the soil pore system. Straw addition promoted a slight increase of colloids electronegative potential but did not alter soil physical properties.

Формування структурно-агрегатного складу та водно-фізичних властивостей сірого лісового ґрунту залежно від мінеральних добрив і тривалої дії вапна

The article presents the research data of structural-aggregate composition, water-physical constants and density of compilation gray forest coarse-dust–light-loam soil for the systematic use of mineral fertilizers and long-term action (8 th - 10 th year) of chemical melioration. The influence of the long action of a single dose of lime on hydrolytic acidity on the transformation parameters of soil properties was established. The presented results of the use CaCO 3 (1,0 Hг), testify to an increase in the quantities of agronomically valuable part of the soil in 3.5 %. At the same time, the volume of adsorbed water by the soil increased and keeping it in the capillary and general space. The shown influence of the systematic use of physiologically acidic mineral fertilizers on the agrophysical and water-physical properties of gray forest soil. Adding N 50 P 30 K 55 led to increased content of dust fraction of soil and reduce its filtration capacity, which is bad for the soil properties. The use of a single and a double dose of mineral fertilizers intensified the peptization of soil aggregates. Due to this, increased the amount of finely-dispersed parts, which is sedimented and accumulated in the lower layers of the soil. As a result, the filtration ability of the soil and absorbing its properties deteriorated, and the density of the composition during vegetation increased.

Relación entre el pH y la disponibilidad de nutrientes para cacao en un entisol de la Amazonia colombiana

El encalado es una práctica común en el manejo de suelos ácidos, sin embargo, la información sobre encalado en suelos cacaoteros de la Amazonia colombiana es precaria. Se construyeron curvas de incubación en un Typic Udorthents fuertemente ácido cultivado con cacao (Theobroma cacao L., Malvaceae), para lo cual se utilizaron dosis crecientes (0 - 1 - 3 - 5 - 7 - 9 - 11 Mg/ha) de cal dolomita (CaMg(CO3)2) y carbonato de calcio (CaCO3), con el fin de conocer el tipo y cantidad de material encalante (ME) de mejor reactividad y el que más favorece los cambios en la acidez: pH, Al3+, H+ y acidez total. Se construyeron los modelos para estimar la dosis de ME necesaria para llevar el suelo al pH deseado (≥5,5). Posteriormente se encaló el suelo en condiciones de campo y se evaluó el efecto en pH, Al3+, Al en solución (Alsol), saturación de aluminio (SAI), capacidad de intercambio catiónico (CIC) y la disponibilidad de N, P, K, Ca, Mg, Zn, Cu, B, Fe y Mn. Los resultados muestran que la mayor reacción de los materiales encalantes en estos suelos se presenta después de 60 días. Aplicaciones de 7 Mg/ha permitieron elevar el pH de 5,5 a 6,0 y disminuir los niveles de Al y Fe, cambios que mejoraron la CIC y la disponibilidad de nutrientes para cacao (Ca, Mg, P, Zn) sin afectar otros nutrientes como N y K.

A Study on Different Dosage of the Cement, Lime and Gypsum Curing Recycled Concrete Debris

The process of research on the compressive strength, the porosity and mechanism of solidifying concrete debris relationship with the dosage of the cement, lime and gypsum is explained based on the filling and cementating theory. According to the research, the dosage of cement curing agent used for cementing and filling the pores among the grains of concrete debris is consistent with that of compressive strength and porosity from different methods of curing concrete debris. However, the dosage of lime and gypsum curing agent are not the case. That is to say, the dosage of cement used for filling and cementing pores in experiment is equal to that from the theory. But the dosage of lime or gypsum from the experiment is less than that of fully filling the pores among concrete debris from theoretical calculation. It is demonstrated that the process of cement solidifying concrete debris complies with the theoretical model of stabilized soil, while the cement-lime or cement-gypsum composite solidifying agent does not. A hypothesis is made that the mechanism of cement solidifing debris is achieved through filling and cementing. Based on microstructure analysis, a conclusion would be made that the mechanism of the curing agent made by cement - lime or cement - gypsum composite is that their interactions produced a large amount of acicular ettringite and gelling materials, and the interaction of these sediment particles is able to improve the microstructure of solidified objects. For this reason, macroscopic compr essive strength of curing concrete debris was improved.

Pulsed corona discharge for improving treatability of coking wastewater

Coking wastewater (CW) contains toxic and macromolecular substances that inhibit biological treatment. The refractory compounds remaining in biologically treated coking wastewater (BTCW) provide chemical oxygen demand (COD) and color levels that make it unacceptable for reuse or disposal. Gas-phase pulsed corona discharge (PCD) utilizing mostly hydroxyl radicals and ozone as oxidants was applied to both raw coking wastewater (RCW) and BTCW wastewater as a supplemental treatment. The energy efficiency of COD, phenol, thiocyanate and cyanide degradation by PCD was the subject of the research. The cost-effective removal of intermediate oxidation products with addition of lime was also studied. The energy efficiency of oxidation was inversely proportional to the pulse repetition frequency: lower frequency allows more effective utilization of ozone at longer treatment times. Oxidative treatment of RCW showed the removal of phenol and thiocyanate at 800 pulses per second from 611 to 227mg/L and from 348 to 86mg/L, respectively, at 42kWh/m3 delivered energy, with substantial improvement in the BOD5/COD ratio (from 0.14 to 0.43). The COD and color of BTCW were removed by 30% and 93%, respectively, at 20kWh/m3, showing energy efficiency for the PCD treatment exceeding that of conventional ozonation by a factor of 3–4. Application of lime appeared to be an effective supplement to the PCD treatment of RCW, degrading COD by about 28% at an energy input of 28kWh/m3 and the lime dose of 3.0kg/m3. The improvement of RCW treatability is attributed to the degradation of toxic substances and fragmentation of macromolecular compounds.