Rates of production of hydroxyl radicals and singlet oxygen from irradiated compost

The use of organic matter from compost to promote the catalytic photodegradation of micropollutants by solar light appears to be environmentally promising. However, quantitative evaluation of the photodegradation potential of the compost is needed. Our goal was to measure the formation rate of hydroxyl radicals and singlet oxygen, two strongly oxidant species, from irradiated compost organic matter. These two reactive species were photogenerated in all of our extracts regardless of the origin of the compost or the extraction procedure; however, their formation rates increased with composting time. Two herbicides and a fungicide were successfully photodegraded when irradiated with simulated or natural solar light in the presence of the compost organic matter or compost suspensions. For reasons of simplification and ease, the use of the latter is recommended in practice.     

The impact of sewage sludge compost on tree peony growth and soil microbiological,and biochemical properties

In order to assess the suitability of sludge compost application for tree peony (Paeonia suffruticosa)–soil ecosystems, we determined soil microbial biomass C (C_mic), basal respiration (R_mic), enzyme activities, and tree peony growth parameters at 0–75% sludge compost amendment dosage. Soil C_mic, R_mic, C_mic as a percent of soil organic C, enzyme (invertase, urease, proteinase, phosphatase, polyphenoloxidase) activities, and plant height, flower diameter, and flower numbers per plant of tree peony significantly increased after sludge compost amendment; however, with the increasing sludge compost amendment dosage, a decreasing trend above 45% sludge compost amendment became apparent although soil organic C, total Kjeldahl N, and total P always increased with the sludge compost amendment. Soil metabolic quotient first showed a decreasing trend with the increasing sludge compost application in the range of 15–45%, and then an increasing trend from compost application of 45–75%, with the minimum found at compost application of 45%. As for the diseased plants, 50% of tree peony under the treatment without sludge compost amendment suffered from yellow leaf disease of tree peony, while no any disease was observed under the treatments with sludge compost application of 30–75%, which showed sludge compost application had significant suppressive effect on the yellow leaf disease of tree peony. This result convincingly demonstrated that ?45% sludge compost application dosage can take advantage of beneficial effect on tree peony growth and tree peony–soil ecosystems.     

Yard waste compost as a stormwater protection treatment for construction sites.

Runoff water quality improvement from three yard waste compost erosion control treatments were compared with two conventional treatments and an untreated control on plots of 3:1 slope during two growing seasons, using natural events and simulated rainfall. Runoff volume, suspended solids, nutrients, biomass, turf shear strength, and turfgrass color scale were monitored. The most effective compost treatment, a 5-cm thick blown compost blanket, produced 12.7 times less runoff and 9.8 times less sediment load than a straw mat and silt fence treatment. The compost treatments generated eight times more biomass than the straw mat treatments. Root development was significantly better on the compost treatments based on turf shear strength measurements. Tilled-in compost was not as effective as a compost blanket at reducing sediment loss, particularly before the establishment of grass on the plot. The cost of compost treatments was similar to that of straw mat with silt fence treatments.     

Bioavailability and degradation of phenanthrene in compost amended soils

Bioavailability in soil of organic xenobiotics such as phenanthrene is limited by mechanisms of diffusion of the xenobiotics within soil micropores and organic matter. The agricultural utilization of compost may reduce the risk connected to organic xenobiotic contamination by means of: (i) a reduction of the bioavailable fraction through an increased adsorption and (ii) an enhanced degradation of the remaining bioavailable fraction through an inoculum of degrading microorganisms. Aim of this work is to test this hypothesis by assessing the effects of compost amendment on the bioavailability and degradation of phenanthrene in soil. Experiments were carried out in both sterilized and non-sterilized conditions, and chemical and microbiological analyses were carried out in order to determine the extent of degradation and bioavailability and to monitor the evolution of the soil micro flora in time. Bioavailability was assessed in sterilized microcosms, in order to assess the physical effects of compost on aging processes without the influence of microbial degradation. Results showed that bioavailability is significantly reduced in soils amended with compost, although no differences were found at the 2 doses of compost studied. In non-sterilized soils the amount of phenanthrene degraded was always higher in the amended soils than in the non-amended one. Microbiological analyses confirmed the presence of a higher number of phenanthrene degraders in the amended soils and in samples of compost alone. These results suggest that compost induces the degradation in soils of easily degradable compounds such as phenanthrene, when the proper bacteria are in the compost; more resistant xenobiotics may instead be trapped by the compost organic matter, thus becoming less available.     

污泥堆肥施用于草坪草栽培：Zn和Cu的分布特征

为了探索污泥堆肥中重金属在土壤一植物系统中的积累与转移特性,通过温室盆栽实验,分析了污泥堆肥对草坪草高羊茅、黑麦草和白三叶生物量积累的情况,研究了污泥堆肥中Zn和Cu在植物和土壤中的分布特征。结果表明,污泥堆肥施用可以有效促进3种草坪草的积累生物量,在0～6kg／m2的污泥堆肥施用量范围内,草坪草的生物量积累随着施用量的增加而提高。土壤中Zn和Cu的含量随污泥堆肥施加量的增加而增大,85％以上的Zn和Cu残留在土壤中。污泥堆肥中的Zn和Cu均可以被植物吸收,随着污泥堆肥施用量的增加,草坪草对Zn和Cu的吸收量增大,但当污泥堆肥施用量超过一定阈值时,草坪草吸收zn和cu不再增加,甚至减少;对于不同的草坪草,这一阈值有所不同。植物对zn和cu的吸收量只占土壤中zn和cu减少量的5％左右。根据生物富集系数（BCF）的计算结果推测,污泥堆肥的施用对土壤环境的影响大于对植物体内累积zn和Cu的影响。     

Compost amendment of Cu-Zn minespoil reduces toxic bioavailable heavy metal concentrations and promotes establishment and biomass production of Bromus carinatus (Hook and Arn.)

A series of lab and greenhouse studies were undertaken to understand how Cu and Zn toxicity influences Bromus carinatus (Hook and Arn.) growth, to what degree an organic amendment (yard waste compost) may reduce Cu and Zn bioavailability in Cu-Zn minespoil and promote plant growth in combination with fertilizer, and how the vertical distribution of compost in the minespoil influences rooting depth. Root Cu and Zn toxicity thresholds were determined to be 1 mgL(-1) and 10 mgL(-1) in solution, respectively. The compost amendment had exceptionally high Cu and Zn binding capacities (0.17 and 0.08 g metal g C(-1), for Cu and Zn, respectively) that were attributed to high compost humic and fulvic acid concentrations. Maximum plant biomass was achieved when minespoil was amended with compost and fertilizer in combination. Fertilizer alone had no effect on plant growth. Mixing compost into the minespoil was essential to promote adequate rooting depth.     

Carbonyl Sulfide Removal with Compost and Wood Chip Biofilters,and in the Presence of Hydrogen Sulfide

Abstract

Carbonyl sulfide (COS) is an odor-causing compound and hazardous air pollutant emitted frequently from wastewater treatment facilities and chemical and primary metals industries. This study examined the effectiveness of biofiltration in removing COS. Specific objectives were to compare COS removal efficiency for various biofilter media; to determine whether hydrogen sulfide (H₂S), which is frequently produced along with COS under anaerobic conditions, adversely impacts COS removal; and to determine the maximum elimination capacity of COS for use in biofilter design. Three laboratory-scale polyvinyl chlo-ride biofilter columns were filled with up to 28 in. of biofilter media (aged compost, fresh compost, wood chips, or a compost/wood chip mixture). Inlet COS ranged from 5 to 46 parts per million (ppm) (0.10–9.0 g/m³fihr). Compost and the compost/wood chip mixture produced higher COS removal efficiencies than wood chips alone. The compost and compost/wood chip mixture had a shorter stabilization times compared with wood chips alone. Fresh versus aged compost did not impact COS removal efficiency. The presence of H₂S did not adversely impact COS removal for the concentration ratios tested. The maximum elimination capacity is at least 9 g/m³·hr for COS with compost media.     

污泥堆肥施用于草坪草栽培:Zn和Cu的分布特征简

为了探索污泥堆肥中重金属在土壤-植物系统中的积累与转移特性,通过温室盆栽实验,分析了污泥堆肥对草坪草高羊茅、黑麦草和白三叶生物量积累的情况,研究了污泥堆肥中Zn和Cu在植物和土壤中的分布特征。结果表明,污泥堆肥施用可以有效促进3种草坪草的积累生物量,在0~6 kg/m²的污泥堆肥施用量范围内,草坪草的生物量积累随着施用量的增加而提高。土壤中Zn和Cu的含量随污泥堆肥施加量的增加而增大,85%以上的Zn和Cu残留在土壤中。污泥堆肥中的Zn和Cu均可以被植物吸收,随着污泥堆肥施用量的增加,草坪草对Zn和Cu的吸收量增大,但当污泥堆肥施用量超过一定阈值时,草坪草吸收Zn和Cu不再增加,甚至减少;对于不同的草坪草,这一阈值有所不同。植物对Zn和Cu的吸收量只占土壤中Zn和Cu减少量的5%左右。根据生物富集系数（BCF）的计算结果推测,污泥堆肥的施用对土壤环境的影响大于对植物体内累积Zn和Cu的影响。     

Induction of PAH-catabolism in mushroom compost and its use in the biodegradation of soil-associated phenanthrene

This paper describes the induction of phenanthrene-catabolism within Phase II mushroom compost resulting from its incubation with (1) phenanthrene, and (2) PAH-contaminated soil. Respirometers measuring mineralization of freshly added 14C-9-phenanthere were used to evaluate induction of phenanthrene-catabolism. Where pure phenanthrene (spiked at a concentration of 400 mg kg(-1) wet wt.) was used to induce phenanthrene-catabolism in compost, induction was measurable, with maximal mineralization observed after 7 weeks phenanthrene-compost contact time. Where PAH-contaminated soil was used to induce phenanthrene-catabolism in un-induced compost, induction was observed after 5 weeks soil-compost contact time. Microcosm-scale amelioration of soil contaminated with 14C-phenanthrene (aged in soil for 516 days prior to incubation with compost) indicated that both induced (using pure phenanthrene) and uninduced Phase II mushroom composts were equally able to promote degradation of this soil-associated contaminant. After 111 days incubation time, 42.7 +/- 6.3% loss of soil-associated phenanthrene was observed in the induced-compost soil mixture, while 36.7 +/- 2.9% loss of soil-associated phenanthrene was observed in the uninduced-compost soil mixture. These results are notable as they indicate that while pre-induction of phenanthrene-catabolism within compost is possible, it does not significantly increase the extent of degradation when the compost is used to ameliorate phenanthrene-contaminated soil. Thus, compost could be used directly in the amelioration of contaminated land i.e. without pre-induction of catabolism.     

Removal of added nitrate in cotton burr compost, mulch compost, and peat: mechanisms and potential use for groundwater nitrate remediation

We conducted batch tests on the nature of removal of added nitrate in cotton burr compost, mulch compost, and sphagnum peat that may be potentially used in a permeable reactive barrier (PRB) for groundwater nitrate remediation. A rigorous steam autoclaving protocol (121 degrees C for 2h each day for three consecutive days) for the cotton burr compost and autoclaving of all labware and the nitrate working solutions resulted in drastically different results compared to the non-autoclaved treatment. In the non-autoclaved cotton burr compost, added nitrate at 20 mg N l(-1) decreased rapidly and was not detected after 3d; whereas, the autoclaved cotton burr compost showed persistent nitrate above 15.5 mg N l(-1) even after 10d, which is comparable with nitrate concentrations above 17.6 mg N l(-1) in a treatment using NaN(3) at 1000 mg l(-1). Dewaxed cotton burr compost showed decreased nitrate reduction compared to the pristine cotton burr compost. No nitrate reduction was detected in the dewaxed sphagnum peat. It is concluded that nitrate removal in the organic media is controlled by microbiologically mediated processes. The use of readily available cotton burr and mulch composts may offer a cost-effective method of nitrate removal from contaminated groundwater.     

Phytoavaelability and extractability of copper and zinc in calcareous soil amended with composted Urban wastes

Abstract

A greenhouse experiment was conducted under simulated field conditions using large‐capacity plastic pots, filled each one with 25 kg of air‐dried calcareous soil. Besides the control, four treatments were prepared by applying separately two rates (20 and 80 Mg ha^‐1) of municipal solid waste (MSW) compost, and co‐composted municipal solid waste and sewage sludge (MSW‐SS). Lettuce was planted and harvested 2.5 months later. The application of composted urban wastes tended to increase Cu concentration in lettuce with respect to the control, but it was only significant when the higher rate of MSW compost was applied. The control showed values of Zn concentration in plant within a deficient range. In general, composted urban wastes treatments had increased Zn concentration values, which were within the sufficiency range. Both treatments with MSW compost increased Cu and Zn uptake in comparison with MSW‐SS co‐compost treatments. At the postharvest, all composted urban wastes treatments increased significantly DTPA‐extractable Cu content in soil with respect to the control; it was also significant the increase in AAAc‐EDTA‐extractable Cu in soil produced by the addition of the higher rate of MSW compost. The application of composted urban wastes increased significantly DTPA‐extractable and AAAc‐EDTA‐extractable Zn contents in soil versus the control, except for the lower rate of MSW‐SS co‐compost. The values of DTPA‐extractable/total ratio for Cu and Zn were under 10%, except for the treatment applying the higher rate of MSW compost which promoted higher values. The values of AAAc‐EDTA‐extractable/total ratio for Cu were above 10% in all treatments including the control. This tendency was also observed in AAAc‐EDTA‐extractable/total ratio for Zn when applying both rates of MSW compost or the higher rate of MSW‐SS co‐compost.     

Regeneration of a compost biofilter degrading high loads of ammonia by addition of gaseous methanol

The long-term stability of a biofilter loaded with waste gases containing NH3 concentrations larger than 100 ppmv was studied in a laboratory-scale compost reactor. At an empty bed residence time (tau) of 21 sec, elimination capacities of more than 300 g NH3/m3/day were obtained at elimination efficiencies up to 87%. Because of absorption and nitrification, almost 80% of the NH3-N eliminated from the waste gas could be recovered in the compost as NH4(+)-N or NO2-/NO3(-)-N. The high elimination capacities could be maintained as long as the NH4+/ NOX- concentration in the carrier material was less than 4 g NH4+/NOx(-)-N/kg wet compost. Above this critical value, osmotic effects inhibited the nitrifying activity, and the elimination capacity for NH3 decreased. To restore the biofilter performance, a carbon source (methanol) was added to reduce NH4+/NOx- accumulated in the compost. Results indicate that methylotrophic microorganisms did convert NH4+/NOx- into biomass, as long as the NO3- content in the compost was larger than 0.1 g NO3(-)-N/kg compost. Removal efficiencies of CH3OH of more than 90% were obtained at volumetric loads up to 11,000 g CH3OH/ m3/day. It is shown that addition of CH3OH is a suitable technique for regenerating the compost material from osmotic inhibition as a result of high NH3 loading. The biofilter was operated for 4 months with alternating load ing of NH3 and CH3OH.     

Differences in p,p'-DDE bioaccumulation from compost and soil by the plants Cucurbita pepo and Cucurbita maxima and the earthworms Eisenia fetida and Lumbricus terrestris

Two plant species, Cucurbita pepo and Cucurbita maxima, and two earthworm species, Eisenia fetida and Lumbricus terrestris, were exposed to soil and compost with equivalent p,p'-DDE contamination. Pollutant bioconcentration was equal in plant roots in both media, but translocation was higher in C. pepo. Bioaccumulation by E. fetida was approximately 6- and 3-fold higher than that by L. terrestris in the soil and compost, respectively. For all species, p,p'-DDE uptake was significantly greater from soil than from compost; 7- to 8-fold higher for plant roots and 3- to 7-fold higher for worms. Abiotic desorption from soil was approximately twice that from the compost. When all the data are normalized for organic-carbon content of the media, the contaminant is more tightly bound by soil than compost. Although the risk associated with p,p'-DDE is higher in soil than compost, important mechanistic differences exist in contaminant binding to organic carbon in the two media.     

Removal of added nitrate in the single, binary, and ternary systems of cotton burr compost, zerovalent iron, and sediment: Implications for groundwater nitrate remediation using permeable reactive barriers

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe(0)) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and autotrophic denitrification in the Fe(0) system. Questions arise as whether the more expensive Fe(0) is more effective than the less expensive carbonaceous solid materials for groundwater nitrate remediation, and whether there is any synergistic effect of mixing the two different types of materials. We carried out batch tests to study the nature and rates of removal of added nitrate in the suspensions of single, binary, and ternary systems of cotton burr compost, Peerless Fe(0), and a sediment low in organic carbon. Cotton burr compost acted as both organic carbon source and supporting material for the growth of indigenous denitrifiers. Batch tests showed that cotton burr compost alone removed added nitrate at a greater rate than did Peerless Fe(0) alone on an equal mass basis with a pseudo-first-order rate constant k=0.0830+/-0.0031 h(-1) for cotton burr compost and a k=0.00223+/-0.00022 h(-1) for Peerless Fe(0); cotton burr compost also removed added nitrate at a faster rate than did cotton burr compost mixed with Peerless Fe(0) and/or the sediment. Furthermore, there was no substantial accumulation of ammonium ions in the cotton burr compost system, in contrast to the systems containing Peerless Fe(0) in which ammonium ions persisted as major products of nitrate reduction. It is concluded that cotton burr compost alone may be used as an excellent denitrification medium in a PRB for groundwater nitrate removal. Further study is needed to evaluate performance of its field applications.     

Characterization of compost biofiltration media.

The effect of compost quality on performance of biofiltration media was investigated. Three types of compost media were characterized in terms of their key properties, including pH, total organic carbon (TOC) and nitrogen, moisture content, oxygen uptake rates and heterotrophic and fungal plate counts. Laboratory-scale biofilter columns were each filled with a different compost medium mixed with buffer and a bulking agent. The columns were operated with a volatile organic compound (VOC) mixture consisting of ethyl alcohol, butyraldehyde, ethyl acetate, and 1,1-diethoxybutane and subjected to various operating conditions. After 13 months, the columns were sampled and post-characterization of the media was performed. A mixture of biosolids/horse manure compost, which had a high initial microbial activity, had the shortest acclimation period. Best overall performance, however, was observed with yard waste compost, which was the most stable medium. Media hydrophobicity was a key factor in long-term performance. Significant changes in compost structure, moisture content, pH, volatile solids, oxygen uptake rates, and microbial population densities were observed over the course of the study. Analyses of organic nitrogen content showed that significant amounts of nitrogen were not depleted from the media.     

Accumulation and fractionation of copper, iron, manganese, and zinc in calcareous soils amended with composts.

Amending soils with compost may lead to accumulation of metals and their fractions at various concentrations in the soil profile. The objectives of this study were to determine 1) the accumulation of Cu, Fe, Mn, and Zn with depth and 2) the distribution of water soluble, exchangeable, carbonate, Fe-Mn oxides, organic and residual forms of each metal in soils amended with MSW compost, co-compost, biosolids compost and inorganic fertilizer (as control). Total concentrations of Cu, Fe, Mn and Zn were concentrated in the 0-22 cm soil layer and scant in the rock layer. These metals were in the decreasing order of Fe > Mn > Zn > or = Cu. Copper, Fe, and Zn were predominantly in the residual form followed by fractions associated with Fe-Mn oxides, carbonate, organic, exchangeable and water soluble in all treatments except MSW compost amended soil where the organic fraction was higher than the carbonate fraction. In fertilizer, co-compost and biosolids compost treated soils Mn concentrated mainly in the Fe-Mn oxides form followed by residual, carbonate, and organic forms whereas, in MSW compost treated soil the same pattern occurred except that Mn organic fraction was higher than that in the carbonate form. The MSW compost has a greater potential to be used as a soil amendment to supply plants with Cu, Mn and Zn than other treatments in calcareous soils of south Florida.     

水葫芦与厨余垃圾混合好氧堆肥中氮素变化及对腐熟度的影响

通过采用间歇式好氧动态堆肥工艺,对厨余垃圾与添加水葫芦的厨余垃圾进行堆肥实验,探讨堆肥进程中全氮、氨基酸态氮、蛋白质的变化及对腐熟度的影响。结果表明,全氮含量在堆肥后期有所提高,分别由1.76%和2.23%提高到3.64%和2.67%;氨基酸态氮含量与微生物活性显著负相关;添加水葫芦使堆体温度提高,促进了蛋白质的快速降解;堆肥中N素是影响种子发芽的主要因素;添加水葫芦能够促进堆肥的腐熟。     

Investigations on the binding mechanism of the herbicide simazine to dissolved organic matter in leachates of compost

14C-labelled simazine was composted together with biowaste on a pilot (m3) scale. The herbicide was quickly bound to the compost matrix. By aqueous extraction of 29 and 200 days old compost (equivalent to thermophilic and mesophilic phase of composting) only 4.2% and 3.1% respectively of the radioactivity in the compost samples could be extracted with water. Analysis of the extracts using high-performance size exclusion chromatography (HPSEC) revealed that the dissolved organic matter (DOM) had molecular weights ranging between 2 and 28 kDa. The amount of DOM-associated radioactivity increased from 53% (day 29) to 65% (day 200) of total extractable radioactivity. The type of binding of the 14C-labelled residues and the DOM was elucidated by silylation of humic matter and subsequent HPSEC. The data demonstrated that besides polar metabolites also intact simazine was bound to the DOM. A distinct shift from rather weak interactions to strong covalent linkages of simazine and its metabolites with increasing age of the compost was observed. The results showed that only low amounts of free simazine and its degradates can be extracted with water. We concluded that the shift towards stable covalent linkages is equivalent to a detoxification of the contaminant in aged compost. Consequently, the use of the analysed compost in its mature stage should not pose an environmental risk to the groundwater or the subsoil.     

Accumulation and mobility of zinc in soil amended with different levels of pig-manure compost

Applying manure compost not only results in zinc accumulation in the soil but also causes an increase in zinc mobility and enhances zinc leaching. In this study, the physical and chemical characteristics of zinc, zinc profiles, and zinc balance were investigated to characterise the fate of zinc in fields where the quality and amount of pig manure compost applied have been known for 13 years. Moreover, we determined zinc fractionation in both 0.1 mol L^?1HCl-soluble (mobile) and -insoluble (immobile) fractions. Adsorption of zinc in the soil was enhanced with increasing total carbon content following the application of pig manure compost. The 159.6 mg ha^?1 year^?1manure applied plot (triplicate) exceeded the Japanese regulatory level after only 6 years of applying pig manure compost, whereas the 53.2 mg ha^?1 year^?1 manure applied plot (standard) reached the regulatory level after 13 years. The zinc loads in the plots were 17.0 and 5.6 kg ha^?1 year^?1, respectively. However, 5.9 % and 17.2 % of the zinc loaded in the standard and the triplicate pig manure compost applied plots, respectively, were estimated to be lost from the plough layer. Based on the vertical distribution of mobile and immobile zinc content, a higher rate of applied manure compost caused an increase in the mobile zinc fraction to a depth of 40 cm. Although the adsorption capacity of zinc was enhanced following the application of pig manure compost, a greater amount of mobile zinc could move downward through the manure amended soil than through non manure-amended soil.     

The adsorption and degradation of chlorpyriphos-methyl, pendimethalin and metalaxyl in solid urban waste compost

To evaluate the feasibility of using compost to prepare substrates for the disposal of pesticide residues, adsorption and degradation studies were carried out on three widely used agricultural pesticides: chlorpyriphos-methyl, pendimethalin and metalaxyl. Obtained from solid urban waste, this compost has been shown to be able to adsorb high levels of chlorpyriphos-methyl and pendimethalin (85%, 100%) whereas metalaxyl was only adsorbed at a level of 37%. However, adding smectite to the compost increased the adsorption of metalaxyl by 117%. Chlorpyriphos-methyl and pendimethalin degraded quickly with half-lives of 1.7 and 14.5 days, respectively, whereas metalaxyl proved more persistent (a half-life of 84 days). Adding ammonium nitrate to the compost accelerated metalaxyl degradation to a half-life of 15 days.