Extracellular Biopolymer Production by Aureobasidium pullulans MTCC 2195 Using Jackfruit Seed Powder

In this present paper, statistical screening and optimization of jackfruit seed powder based medium components were investigated for pullulan production from Aureobasidium pullulans. Seven medium variables jackfruit seed powder, K₂HPO₄, yeast extract, (NH₄)₂SO₄, NaCl, MgSO₄·7H₂O and ZnSO₄·7H₂O were screened by employing Plackett–Burman (PB) method. PB method showed jackfruit seed powder, ZnSO₄·7H₂O, K₂HPO₄ and yeast extract were significant. Central composite design of response surface method applied to optimize the significant variables identified from the PB experiment. Statistical analysis of the experimental results showed optimal values were found to be jackfruit seed powder 2 % (w/v), K₂HPO₄ 0.55 % (w/v), yeast extract 0.30 % (w/v) and ZnSO₄·7H₂O 0.006 % (w/v) with maximum pullulan concentration of 18.76 (g/L). Maximum pullulan concentration of 17.95 (g/L) was observed in the validation experiment. This experimental result explained the model was fitted 96 % as compare with the result predicted by response surface method.     

Aerobic in situ stabilization of Landfill Konstanz Dorfweiher: Leachate quality after 1 year of operation

Modern landfill understanding points out controlled operation of landfills. Emissions from landfills are caused mainly by anaerobic biodegradation processes which continue for very long time periods after landfill closure. In situ landfill stabilization aims controlled reduction of emissions towards reduced expenditures as well as aftercare measures. Since April 2010, a new in situ stabilization technique is being applied at a pilot scale landfill (BAIV) within Landfill Konstanz Dorfweiher. This new method utilizes intermittent aeration and leachate recirculation for waste stabilization. In this study, influence of this technique on leachate quality is investigated. Among many other parameters, leachate analyses were conducted for COD, BOD₅, NH₄–N, NO₂–N, NO₃–N, TKN and chloride besides continuously on site recorded pH, electrical conductivity and oxidation–reduction potential (ORP). Results from leachate quality analyses showed that biological activity in the landfill was accelerated resulting in initial higher leachate strength and reduced emission potential of landfill. During full scale in situ aeration, ambient conditions differ from optimized laboratory scale conditions which mainly concern temperature increase and deficient aeration of some landfill parts (Ritzkowski and Stegmann, 2005). Thus, as a field application results of this study have major importance on further process optimization and application.     

Pollution profiles and physicochemical parameters in old uncontrolled landfills

The long-term effectiveness of the geological barrier beneath municipal-waste landfills is a critical issue for soil and groundwater protection. This study examines natural clayey soils directly in contact with the waste deposited in three landfills over 12 years old in Spain. Several physicochemical and geological parameters were measured as a function of depth. Electrical conductivity (EC), water-soluble organic carbon (WSOC), Cl⁻, NH₄⁺, Na⁺ and exchangeable NH₄⁺ and Na⁺ were used as parameters to measure the penetration of landfill leachate pollution. Mineralogy, specific surface area and cationic-exchange capacities were analyzed to characterize the materials under the landfills. A principal component analysis, combined with a Varimax rotation, was applied to the data to determine patterns of association between samples and variables not evident upon initial inspection. The main factors explaining the variation in the data are related to waste composition and local geology. Although leachates have been in contact with clays for long time periods (13-24 years), WSOC and EC fronts are attenuated at depths of 0.2-1.5 m within the clay layer. Taking into account this depth of the clayey materials, these natural substrata (>45% illite-smectite-type sheet silicates) are suitable for confining leachate pollution and for complying with European legislation. This paper outlines the relevant differences in the clayey materials of the three landfills in which a diffusive flux attenuation capacity (A_c) is defined as a function (1) of the rate of decrease of the parameters per meter of material, (2) of the age and area of the landfill and (3) of the quantity and quality of the wastes.     

The influence of atmospheric n deposition on nitrous oxide and nitric oxide fluxes and soil ammonium and nitrate concentrations

The deposition of atmospheric N to soils provides sources of available N to the nitrifying and denitrifying microbial community and subsequently influences the rate of NO and N₂O emissions from soil. We have investigated the influence of three different sources of enhanced N deposition on NO and N₂O emissions 1) elevated NH₃ deposition to woodlands downwind of poultry and pig farms, 2) increased wet cloud and occult N deposition to upland forest and moorland and 3) enhanced N deposition to trees as NO^? ₃ and NH⁺ ₄ aerosol. Flux measurements of NO and N₂O were made using static chambers in the field or intact and repacked soil cores in the laboratory and determination of N₂O by gas chromatography and of NO by chemiluminescence analysis. Rates of N deposition to our study sites were derived from modelled estimates of N deposition, NH₃ concentrations measured by passive diffusion and inference from measurements of the ²¹⁰Pb inventory of soils under tree canopies compared with open grassland. NO and N₂O emissions and KCl-extractable soil NH⁺ ₄ and NO^? ₃ concentrations all increased with increasing N deposition rate. The extent of increase did not appear to be influenced by the chemical form of the N deposited. Systems dominated by dry-deposited NH₃ downwind of intensive livestock farms or wet-deposited NH⁺ ₄and NO^? ₃ in the upland regions of Britain resulted in approximately the same linear response. Emissions of NO and N₂O from these soils increased with both N deposition and KCl extractable NH⁺ ₄, but the relationship between NH⁺ ₄ and N deposition (ln NH⁺ ₄ = 0.62 ln N_deposition+0.21, r ² = 0.33, n = 43) was more robust than the relationship between N deposition and soil NO and N₂O fluxes.     

Thermogravimetric and XRD study of the effects of chloride salts on the thermal decomposition of mercury compounds

In this paper, the effects of chloride salt (MgCl₂, CaCl₂ or NaCl) addition on the thermal decomposition of five inorganic mercury compounds (HgCl₂, HgS, Hg(NO₃)₂·H₂O, HgO, and HgSO₄) were investigated by thermogravimetric analysis. Mercury-contaminated soil samples collected from Inner Mongolia were used to verify the results. The desorption temperatures of the mercury compounds increased in the following order: HgCl = HgCl₂ < HgS < Hg(NO₃)₂·H₂O < HgO < HgSO₄. Among the chloride salts, MgCl₂ had the greatest effect on thermal desorption of the mercury compounds, with the greatest reduction in the initial temperature of thermal desorption. After MgCl₂ treatment, the mercury removal rates for the soil were 65.67–81.35 % (sample A), 70.74–84.91 % (sample B), and 69.08 % (sample C). The increase in the mercury removal rate for sample C with addition of MgCl₂ was particularly large (34.96–69.08 %). X-Ray diffraction analysis of white crystals from the thermal desorption with MgCl₂ indicated that MgCl₂ promoted conversion of the mercury compounds in the soil to mercury(II) chloride and dimercury dichloride. This transformation is beneficial for applying thermal desorption to remedy mercury-contaminated soils and treat of mercury containing waste.     

The Influence of Atmospheric N Deposition on Nitrous Oxide and Nitric Oxide Fluxes and Soil Ammonium and Nitrate Concentrations

The deposition of atmospheric N to soils provides sources of available N to the nitrifying and denitrifying microbial community and subsequently influences the rate of NO and N₂O emissions from soil. We have investigated the influence of three different sources of enhanced N deposition on NO and N₂O emissions 1) elevated NH₃ deposition to woodlands downwind of poultry and pig farms, 2) increased wet cloud and occult N deposition to upland forest and moorland and 3) enhanced N deposition to trees as NO ₃ ^– and NH ₄ ⁺ aerosol. Flux measurements of NO and N₂O were made using static chambers in the field or intact and repacked soil cores in the laboratory and determination of N₂O by gas chromatography and of NO by chemiluminescence analysis. Rates of N deposition to our study sites were derived from modelled estimates of N deposition, NH₃ concentrations measured by passive diffusion and inference from measurements of the ²¹⁰Pb inventory of soils under tree canopies compared with open grassland. NO and N₂O emissions and KCl-extractable soil NH ₄ ⁺ and NO ₃ ^– concentrations all increased with increasing N deposition rate. The extent of increase did not appear to be influenced by the chemical form of the N deposited. Systems dominated by dry-deposited NH₃ downwind of intensive livestock farms or wet-deposited NH ₄ ⁺ and NO ₃ ^– in the upland regions of Britain resulted in approximately the same linear response. Emissions of NO and N₂O from these soils increased with both N deposition and KCl extractable NH ₄ ⁺ , but the relationship between NH ₄ ⁺ and N deposition (ln NH ₄ ⁺ = 0.62 ln N_deposition + 0.21, r ² = 0.33, n = 43) was more robust than the relationship between N deposition and soil NO and N₂O fluxes.     

Fate of saline ions in a planted landfill site with leachate recirculation

Recirculation of leachate on a covered landfill site planted with willows or other highly evapotranspirative woody plants is an inexpensive option for leachate management. In our study, a closed landfill leachate recirculation system was established on a rehabilitated municipal solid waste landfill site with planted landfill cover. The main objective of the study was to evaluate the sustainability of the system with regard to high hydraulic loads of the landfill leachate on the landfill cover and high concentrations of saline ions, especially potassium (K⁺), sodium (Na⁺) and chloride (Cl^?), in leachate.The results of intensive monitoring, implemented during May 2004 and September 2007, including leachate, soil and plant samples, showed a high sustainability of the system regarding saline ions with the precipitation regime of the studied region. Saline ion concentrations in leachates varied between 132 and 2592 mg Cl^? L^?1, 69 and 1310 mg Na⁺ L^?1 and between 66 and 2156 mg K⁺ L^?1, with mean values of 1010, 632 and 686 mg L^?1, respectively. Soil salinity, measured as soil electrical conductivity (EC), remained between 0.17 and 0.38 mS cm^?1 at a depth between 0 and 90 cm. An average annual precipitation of 1000 mm provided sufficient leaching of saline ions, loaded by irrigation with landfill leachate, from the soil of the landfill cover and thus prevented possible salinity shocks to the planted willows.     

Evaluation of landfill leachate treatment by advanced oxidative process by Fenton’s reagent combined with membrane separation system

A high content of refractory organic matter, ammonia and toxic compounds is characteristic of landfill leachate. Advanced oxidative processes (AOPs) are an attractive alternative for landfill leachate treatment. However, when applied as a unique process treatment, they do not provide a complete solution for the effluent treatment. Combining AOP with a membrane separation process (MSP) presents a number of benefits and provides an adequate solution for this problem. With this in mind, the present work aims to evaluate, using a bench scale, leachate treatability through AOP by Fenton’s reagent (AOP/Fenton) combined with microfiltration (MF) and nanofiltration (NF). A high efficient removal of COD (63%), true color (76%) and humic substances (50%) was observed during AOP/Fenton under optimized conditions (1.7 g H₂O₂/g COD_{raw leachate}; FeSO₄·7H₂O:H₂O₂ = 1:5.3; pH = 3.8; reaction conditions = 115 rpm/28 min). According to the evaluated parameters, MSP presented an efficient complementary treatment, in which the integrity of the stages was sufficient for reaching regulatory levels in the effluent (Deliberação Normativa Conjunta COPAM/CERH-MG N^o. 1, May 5, 2008).     

Development of Stream Water Chemistry during Spring Melt in a Northern Hardwood Forest

The role of snowmelt and subsurface hydrology in determiningthe chemistry of a small headwater stream in the TurkeyLakes Watershed (TLW) was evaluated for the spring meltperiods 1992 to 1996. Spring runoff is the dominanthydrological event at the TLW each year. Processesoccurring within the snowpack during snowmelt wereprincipally responsible for the above-ground changes inchemical fluxes relative to bulk deposition (the effect ofwinter throughfall was minimal). Large changes in chemicalfluxes occurred below ground. Organic matter decomposition,weathering, nitrification, and element cycling are some ofthe more important below-ground processes that operateduring the snow accumulation and ablation season and controlthe composition of the water ultimately appearing in thestream. Maximum stream discharge was accompanied byelevated concentrations of H⁺, NO₃ ^-, K⁺,NH₄ ⁺, DOC, Al and Mn, but reduced levels ofCa²⁺, Mg²⁺, SO₄ ^2- and SiO₂. Theconcentration-discharge relationships were consistent withwater movement through and above the forest floor duringpeak discharge, a flowpath facilitated by rapid infiltrationof meltwater and the existence of a relatively impermeablelayer in the mineral soil creating a perched water table. Averaged over the five periods of snow accumulation andablation, it was estimated that pre-melt stream flow, andwater routed through the forest floor and through the uppermineral soil contributed 9, 28 and 63%, respectively, ofthe discharge measured at the outlet of the catchment. Theforest floor contribution would be greater at peak dischargeand at higher elevations. An end-member mixing modelestimated concentrations of SO₄ ^2-, NO₃ ^-,Cl^-, Ca²⁺, Mg²⁺, Na⁺ and Al that werecomparable to average values measured in the stream. Othervariables (NH₄ ⁺, H⁺, K⁺ and DOC) wereover-estimated implying retention mechanisms operatingoutside the model assumptions.     

Effects of leachate accumulation on landfill stability in humid regions of China

Leachate levels are important to landfill stability and safety. High leachate or water levels often lead to landfill instability, which can cause accidents. Here a case study of a landfill located in a humid region of southern China is presented. Leachate distribution and quality were systematically analyzed, and the effect of leachate level on waste-mass stability was assessed. Boreholes were drilled in the field, samples were analyzed in the laboratory, and a simulation was performed. In addition, the safety and stability of the landfill was evaluated. The leachate level in the landfill was 9–19 m, which was higher than the top of the dam crest (8–20 m). Leachate accounted for more than 1/4 of the total landfill storage capacity. The contaminant concentration of the leachate samples collected directly from the waste body was very high, with large variation among the samples. The mean concentrations of NH₃–N, BOD, and COD from the waste body were 5404, 14,136, and 22,691 mg/L, nearly 2.7, 2.4, and 1.8 times the mean concentrations in the leachate pond, respectively. Three series of shear strength parameters were used in a slope stability analysis, and a limit equilibrium method was used to calculate the factor of safety (Fs). The analysis showed that Fs could be affected by potential anisotropy in the shear strength of the waste. The minimum values of Fs corresponding to series I were 1.84 and 1.17 for units ? and II, respectively. The Fs value of unit II was significantly lower than the safe design value (1.25). In addition, Fs decreased with increase in the normalized height of the leachate level, h/H, where h is the height of the leachate mound and H is the maximum thickness of the landfill. If the h/H values of units I and II are kept below 50% and 40%, respectively, a safe design value of 1.25 for Fs can be guaranteed. Therefore, some measures to prevent risk should be considered.     

Greenhouse gas emissions from landfill leachate treatment plants: A comparison of young and aged landfill

With limited assessment, leachate treatment of a specified landfill is considered to be a significant source of greenhouse gas (GHG) emissions. In our study, the cumulative GHG emitted from the storage ponds and process configurations that manage fresh or aged landfill leachate were investigated. Our results showed that strong CH₄ emissions were observed from the fresh leachate storage pond, with the fluxes values (2219–26,489 mg C m^?2 h^?1) extremely higher than those of N₂O (0.028–0.41 mg N m^?2 h^?1). In contrast, the emission values for both CH₄ and N₂O were low for the aged leachate tank. N₂O emissions became dominant once the leachate entered the treatment plants of both systems, accounting for 8–12% of the removal of N-species gases. Per capita, the N₂O emission based on both leachate treatment systems was estimated to be 7.99 g N₂O–N capita^?1 yr^?1. An increase of 80% in N₂O emissions was observed when the bioreactor pH decreased by approximately 1 pH unit. The vast majority of carbon was removed in the form of CO₂, with a small portion as CH₄ (<0.3%) during both treatment processes. The cumulative GHG emissions for fresh leachate storage ponds, fresh leachate treatment system and aged leachate treatment system were 19.10, 10.62 and 3.63 Gg CO₂ eq yr^?1, respectively, for a total that could be transformed to 9.09 kg CO₂ eq capita^?1 yr^?1.     

Effects of Long-Term Application of Ammonium Sulphate on Nitrogen Fluxes in a Beech Ecosystem at Solling, Germany

To study the effects of elevated inputs of acidity and nitrogen (N), 1000 mmol m^-2 a^-1 of ammonium sulphate (NH₄NO₃) equivalent to an input of potential acidity of 2000 mmol m^-2 a^-1 was applied annually for 11 yr between 1983 and 1993 in a beech forest at Solling, Germany. Most of the applied NH₄ ⁺ was nitrified in the litter layer and in the upper mineral soil. N in soil leachate quickly responded to the elevated input, but most of the applied N was stored in the soil or left the ecosystem via pathways other than soil output. Leaching of N from the soil increased until the last year of N addition. After the last N application, N fluxes decreased rapidly to low values. The buffering of acidity produced by the nitrification of the applied NH₄ ⁺ was caused mainly by three different processes: (i) sulphur (S) retention, (ii) release of aluminium, (iii) release of base cations. Retention of S took place mostly in the subsoil. 72% of the S input was recovered in output after 14 years of the experiment. Due to the increased fluxes of mobile anions with soil solution, outputs of cations increased drastically.     

Characterization and control of odorous gases at a landfill site: a case study in Hangzhou, China

Municipal solid waste (MSW) landfills are one of the major sources of offensive odors potentially creating annoyance in adjacent communities. At the end of May 2007, an odor pollution incident occurred at the Tianziling landfill site, Hangzhou, China, where the residents lodged complaints about the intense odor from the landfill, which drew a significant attention from the government. In this study, ambient air monitoring was conducted at the Tianziling landfill site. The main odor composition of the gas samples collected on June 1st 2007 and the reduction of various odorous gases from the samples collected on June 1st 2009 due to the applied odor control techniques were determined using gas chromatography-mass spectrometry (GC-MS). In addition, variations of primary odorous gaseous (NH₃ and H₂S) concentrations at different locations in the landfill site from July 2007 to June 2009 were also investigated by using classical spectrophotometric methods. Results showed that a total of 68 volatile compounds were identified among which H₂S (56.58-579.84 μg/m³) and NH₃ (520-4460 μg/m³) were the notable odor components contributing to 4.47-10.92% and 83.91-93.94% of total concentrations, respectively. Similar spatial and temporal shifts of H₂S and NH₃ concentrations were observed and were significantly affected by environmental factors including temperature, air pressure and wind direction. Odor pollution was worse when high temperature, high humidity, low air pressure, and southeast, northeast or east wind appeared. Moreover, the environmental sampling points of the dumping area and the leachate treatment plant were found to be the main odor sources at the Tianziling landfill site. The odor control technologies used in this project had a good mitigating effect on the primary odorous compounds. This study provides long-term valuable information concerning the characteristics and control of odors at landfill sites in a long run.     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

Impact of nitrate-enhanced leachate recirculation on gaseous releases from a landfill bioreactor cell

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N₂O emissions. During several weeks, we monitored gas concentrations in the landfill gas collection system as well as surface gas releases with a series of seven static chambers. These devices were directly connected to a gas chromatograph coupled to a flame ionisation detector and an electron capture detector (GC-FID/ECD) placed directly on the field. Measurements were performed before, during and after recirculation of raw leachate and nitrate-enhanced leachate. Raw leachate recirculation did not have a significant effect on the biogas concentrations (CO₂, CH₄ and N₂O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N₂O concentrations in the gas collected from the recirculation trench (100-fold increase from 0.2 ppm to 23 ppm). In the common gas collection system however, this N₂O increase was no more detectable because of dilution by gas coming from other cells or ambient air intrusion. Surface releases through the temporary cover were characterized by a large spatial and temporal variability. One automated chamber gave limited standard errors over each experimental period for N₂O releases: 8.1 ± 0.16 mg m^?2 d^?1 (n = 384), 4.2 ± 0.14 mg m^?2 d^?1 (n = 132) and 1.9 ± 0.10 mg m^?2 d^?1 (n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N₂O gaseous surface releases and recirculation events were evidenced. Estimated N₂O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection.     

Chemical characterization of emissions from a municipal solid waste treatment plant

Gaseous emissions are an important problem in municipal solid waste (MSW) treatment plants. The sources points of emissions considered in the present work are: fresh compost, mature compost, landfill leaks and leachate ponds. Hydrogen sulphide, ammonia and volatile organic compounds (VOCs) were analysed in the emissions from these sources. Hydrogen sulphide and ammonia were important contributors to the total emission volume. Landfill leaks are significant source points of emissions of H₂S; the average concentration of H₂S in biogas from the landfill leaks is around 1700 ppmv. The fresh composting site was also an important contributor of H₂S to the total emission volume; its concentration varied between 3.2 and 1.7 ppmv and a decrease with time was observed. The mature composting site showed a reduction of H₂S concentration (<0.1 ppmv). Leachate pond showed a low concentration of H₂S (in order of ppbv). Regarding NH₃, composting sites and landfill leaks are notable source points of emissions (composting sites varied around 30–600 ppmv; biogas from landfill leaks varied from 160 to 640 ppmv).Regarding VOCs, the main compounds were: limonene, p-cymene, pinene, cyclohexane, reaching concentrations around 0.2–4.3 ppmv.H₂S/NH₃, limonene/p-cymene, limonene/cyclohexane ratios can be useful for analysing and identifying the emission sources.     

Mathematical model analysis of Fenton oxidation of landfill leachate

The treatment of concentrated landfill leachate rejected from reverse osmosis (RO) with Fenton process was studied, and the system model was developed through the examination of reaction kinetics. The leachate is typically non-biodegradable with low BOD₅/COD ratio 0.01. The oxidation reactions of Fenton process was found to be a two-stage process, where a fast initial reaction (H₂O₂/Fe²⁺) was followed by a much slower one (H₂O₂/Fe³⁺). A simple and more accurate mathematics model based on COD and TOC removals has been derived successfully to describe the two-stage reaction kinetics. The two corresponding parameters involved in this model have been identified as the initial reaction rate and the maximum oxidation removal efficiency, respectively. It was found to be very useful for evaluating the performance of Fenton system and/or for process design using the two parameters under different experimental conditions.     

Biohydrogen using leachate from an industrial waste landfill as inoculum

Since hydrogen is a renewable energy source, biohydrogen has been researched in recent years. However, data on hydrogen fermentation by a leachate from a waste landfill as inoculum are scarce. We investigated hydrogen production using a leachate from an industrial waste landfill in Kanagawa Prefecture. The results showed no methane gas production, and the leachate was a suitable inoculum for hydrogen fermentation. The maximum H₂ yield was 2.67 mol of H₂ per mol of carbohydrate added, obtained at 30°C and an initial pH of 7. The acetate and butyrate production was significant when the H₂ yield was higher. Oxidation–reduction potential analysis of the culture suggested that hydrogen-producing bacteria in the leachate were facultative anaerobic. Scanning electron microscope observations revealed that the hydrogen-producing bacteria comprised bacilli about 2 μm in length.     

Preparation of zeolitic material with simultaneous removal of NH4 + and PO4 3− from paper sludge ash via acid leaching

This study investigates the preparation of zeolitic material with removal of both NH₄ ⁺ and PO₄ ^3? from paper sludge ash (PSA) via acid leaching. PSA typically has a low Si and high Ca content, owing to the presence of calcite fillers. Acid leaching with 3 M HCl was used firstly to reduce the Ca content of the PSA, whereafter a zeolite-P (Na-P) product with high cation exchange capacity (CEC) was synthesized through reaction with 2.5 M NaOH solution at 80 °C. Ca-P zeolitic products were prepared by Ca-treatment with the leachant that had been in contact with the PSA. The product with high CEC capacity including Na-P could be synthesized from the acid-leached ash, and the high Ca content in the ash could be reduced by extraction of the Ca into the leachant via the acid leaching. The Ca-P zeolitic product could be prepared by Ca-treatment with the solution obtained from neutralization of the leachant with NaOH. This product was capable of removing NH₄ ⁺ and PO₄ ^3? from aqueous solution, simultaneously.     

Nitrous Oxide in Agricultural Drainage Waters Following Field Fertilisation

Dissolved nitrous oxide (N₂O), nitrate (NO₃ ^-), and ammonium (NH₄ ⁺) concentrations in an agricultural field drain were intensively measured over the period of field nitrogen (N) fertilisation and for several weeks thereafter. Supersaturations of dissolved N₂O were observed in field drain waters throughout the study. On entry to an open drainage ditch, concentrations of dissolved N₂O rapidly decreased and a total N₂O-N emission via this pathway of 13.2 g over the period of study (45 days) was calculated. This compared with a predicted emission of the order of 300 g, based on measured losses of NO₃ ^- and NH₄ ⁺ in the field drainage water, and the default IPCC emission factor of 0.01 kg N₂O-N per kg Nentering rivers and estuaries. In contrast to widespread evidence of a clear relationship between the amount of N applied to agricultural land and subsequent direct N₂O emission from the soil surface, the relationship between the amount of N₂O in soil drainage waters and the amount of N applied was poor. We conclude that the complexity, both spatially and temporally, of the processes ultimately responsible for the amount of N₂O in agricultural drainage waters make a straightforward relationship between N₂O concentration and N application rate unlikely in all but the simplest of systems.