Conventional Compost Research Articles

Vermicompost as a Soil Supplement to Improve Growth and Yield of Parsley

ABSTRACT Organically based nutrient sources may provide an alternative to synthetic fertilizers to provide nutrition for plants. Vermicomposting may be able to mitigate problems with detrimental microbes, especially thermo-tolerant pathogens in conventional compost. Information is lacking on effects of vermicomposted animal manure on leafy vegetables. Vermicomposted cattle manure, in combinations with soil [0:100, 10:100, 20:100, and 30:100 (v/v)], was tested to determine how it affects growth, yield, and chemical characteristics of parsley (Petroselinum crispum Mill.) in a greenhouse. Growth and yield parameters were measured at 60 days after sowing. Results indicated that addition of vermicompost to soil increased plant height and numbers of leaves. Total yields and amounts of potassium, phosphorus, and total soluble solids were greater for parsley plants grown in the 10:100 combination.

Comparison of bio-augmentation and composting for remediation of oily sludge: A field-scale study in China

Two bioremediation technologies were performed in order to explore a better treatment process for an oily sludge restoration in China during 2004. The bioremediation by augmentation of biopreparation was compared with a conventional composting. The oily sludge and oil-polluted soil were received from an oil production plant. The total hydrocarbon content (THC) varied from 327.7 to 371.2gkg−1 of dry sludge and the THC in contaminated soil was 151.0gkg−1. Before application of preparation, straw, sawdust, top sand and pure soil were added in different proportions to the sludge and soil and mixed thoroughly. Such sludge and soil composites were used for negative controls and for activation of indigenous oil degrading microorganisms with addition of fertilizer (positive controls). For composting, crude manure and straw were added to the oily sludge and the THC was 101.4gkg−1. The biopreparation was applied every 2 weeks and experiment lasted 56 days under the ambient temperature. The sludge was mixed and watered every 3 days. After three times of biopreparation application, the THC decreased by 46–53% in the oily sludge and soil, while in the positive controls (activation of indigenous microorganisms) the THC decreased by 13–23%, and there was no oil degradation in negative controls After composting, the THC decreased by 31% in the oily sludge. The planting of Tall Fescue (Festuca arundinace) revealed a decrease of sludge toxicity after application of both bioremediation technologies and additionally decreased the THC by 5–7%.

Fungal biocatalysts in the biofiltration of VOC-polluted air

Gas-phase biofilters used for the treatment of waste gases were originally packed with compost or other natural filter beds containing indigenous microorganisms. Over the past decade much effort has been made to develop new carrier materials, more performant biocatalysts and new types of bioreactors. Elimination capacities reached nowadays are 5 to 10 times higher than those originally reported with conventional compost biofilters. With the recently developed inert filter beds, inoculation is a prerequisite for successful start-up and operation. Either non-defined mixed cultures or pure bacterial cultures have originally been used. The search for efficient fungal biocatalysts started only a few years ago, mainly for the biofiltration of waste gases containing hydrophobic compounds, such as styrene, α-pinene, benzene, or alkylbenzenes. In this review, recently isolated new fungal strains able to degrade alkylbenzenes and other related volatile organic pollutants are described, as well as their major characteristics and their use as biocatalysts in gas-phase biofilters for air pollution control. In biofiltration, the most extensively studied organism belongs to the genus Exophiala, although strains of Scedosporium, Paecilomyces, Cladosporium, Cladophialophora, and white-rot fungi are all potential candidates for use in biofilters. Encouraging results were obtained in most of the cases in which some of those organisms were present in gas-phase biofilters. They allow reaching high elimination capacities and are resistant to low pH values and to reduce moisture content.

Intensive bioconversion of sewage sludge and food waste by Bacillus thermoamylovorans

The main aim of this work was to intensify conventional composting of a mixture of sewage sludge and solid food wastes by a one-stage thermophilic bioconversion of these wastes into an organic fertilizer. An intensive process was carried out in a closed system, with or without addition of a starter culture of Bacillus thermoamylovorans. The most effective thermophilic bioconversion of the mixture of food waste and sewage sludge, with addition of starter culture, was when the pH was buffered with calcium carbonate, or the pH drop in the material was prevented by preliminary removal of sulphides from sewage sludge by hydrogen peroxide.

Effects of earthworm casts and compost on soil microbial activity and plant nutrient availability

Vermicomposting differs from conventional composting because the organic material is processed by the digestive systems of worms. The egested casts can be used to improve the fertility and physical characteristics of soil and potting media. In this study, the effects of earthworm casts (EW), conventional compost (CP) and NPK inorganic fertilizer (FT) amendments on N mineralization rates, microbial respiration, and microbial biomass were investigated in a laboratory incubation study. A bioassay with wheat ( Triticum aestivium L.) was also conducted to assess the amendment effects on plant growth and nutrient uptake and to validate the nutrient release results from the incubation study. Both microbial respiration and biomass were significantly greater in the CP treatment compared to EW treatment for the initial 35 days of incubation followed by similar respiration rates and biomass to the end of the study at 70 days of incubation. Soil NO 3 − increased rapidly in the EW and CP treatments in the initial 30 days of incubation, attaining 290 and 400 mg N kg −1 soil, respectively. Nitrate in the EW treatment then declined to 120 mg N kg −1 soil by day 70, while nitrate in the CP treatment remained high. While ammonium levels decreased in the CP treatment as nitrate level increased with increasing incubation time, a low level of ammonium was maintained in the EW treatment throughout the incubation. The wheat bioassay study included two additional cast treatments (EW-N and EW2) to have treatments with higher levels of N input. Plants grown with CP or FT treatment had a lower shoot biomass and higher shoot N content than in EW-N and EW-2 treatments, and also showed symptoms of salinity stress. Ionic strength and other salinity indicators in the earthworm cast treatments were much lower than in the CP treatment, indicating a lower risk of salinity stress in casts than in compost. All cast and compost amendments significantly increased wheat P and K uptake compared to either the non-amended control or the mineral fertilizer treatment. The results show that casts are an efficient source of plant nutrients and that they are less likely to produce salinity stress in container as compared to compost and synthetic fertilizers.

Changes in trophic structure of soil arthropods after the application of vermicomposts

The trophic structure of soil arthropods in earthworm casts or vermicomposts produced by Eisenia fetida (Savigny) from paper waste, food waste and cow manure, and in field trials was studied during summer 1999. The numbers of soil arthropods in the soil were counted before treatment (as a control), in the vermicomposts, and after application of vermicomposts to soil in the field. The vermicomposts were applied to soil in rows of tomatoes and peppers, at rates of 4.5 ton ha –1, and the numbers of soil arthropods in trophic groups were compared with those in soil receiving conventional composts and inorganic fertilizers. All treatments received the same total amounts of nutrients. Most of the vermicomposts were rich in microbial biomass-N. There was a tendency for the application of inorganic fertilizers, and conventional compost, to tomato and pepper plots to decrease the numbers of trophic groups of soil arthropods. The applications of vermicomposts increased the number of trophic groups of soil arthropods.

Interactions between the Pathogen Trichoderma harzianum Th2 and Agaricus bisporus in Mushroom Compost

Trichoderma harzianum biotype Th2, re- sponsible for green mold disease, appeared in the North of France by the end of 1997. Cocultures of Agaricus bisporus with four French Th2 isolates and three less aggressive Trichoderma species were per- formed in conventional compost to further our un- derstanding of how Trichoderma Th2 establishes and competes with the button mushroom. Spore germi- nation of Th2 isolates was little affected by A. bisporus mycelium while that of other species was strongly in- hibited. Th2 mycelium flourished in compost unin- oculated or inoculated with A. bisporus, but myceli- um of the button mushroom is required for intensive sporulation. No fungistatic effect of the mycelium of Trichoderma on A. bisporus was observed in compost, but when Th2 produced spores, toxicity toward A. bisporus was detected. A simultaneous growth of A. bisporus and Th2 was observed before the mycelium of Agaricus stimulated the Th2 sporulation. As soon as sporulation occurred the mycelial growth of A. bis- porus was dramatically reduced and typical green

Interactions between the pathogen Trichoderma harzianum Th2 and Agaricus bisporus in mushroom compost

Trichoderma harzianum biotype Th2, responsible for green mold disease, appeared in the North of France by the end of 1997. Cocultures of Agaricus bisporus with four French Th2 isolates and three less aggressive Trichoderma species were performed in conventional compost to further our understanding of how Trichoderma Th2 establishes and competes with the button mushroom. Spore germination of Th2 isolates was little affected by A. bisporus mycelium while that of other species was strongly inhibited. Th2 mycelium flourished in compost uninoculated or inoculated with A. bisporus, but mycelium of the button mushroom is required for intensive sporulation. No fungistatic effect of the mycelium of Trichoderma on A. bisporus was observed in compost, but when Th2 produced spores, toxicity toward A. bisporus was detected. A simultaneous growth of A. bisporus and Th2 was observed before the mycelium of Agaricus stimulated the Th2 sporulation. As soon as sporulation occurred the mycelial growth of A. bisporus was dramatically reduced and typical green mold rapidly developed.

Prerequisites for biodegradable plastic materials for acceptance in real-life composting plants and technical aspects

For bioplastic materials to be accepted in composting plants, biodegradability alone is not sufficient. As important is the disintegration during composting. This is the physical falling apart of the bioplastic material, or more precisely of the product that has been made from it, into fine visually indistinguishable fragments at the end of a typical composting cycle. The property of disintegration is measured in a pilot-scale or full-scale composting test. The test substance is subjected to a spontaneous composting process for a duration of 12 weeks. At the end, a sieving over 2 mm followed by a precise sorting analysis is executed. It may be that a bioplastic passes the test at a specific thickness but fails the test at a higher thickness. It must also be demonstrated that the bioplastic materials have no negative effect on compost quality. This involves chemical analyses e.g. heavy metals, required to evaluate conventional compost quality. In addition, ecotoxicity tests are advised, including plant germination tests as well as animal toxicity tests. The purpose of these tests is to make sure that small additives (e.g. in the < 1% range) falling beyond the sensitivity of biodegradation tests as well as metabolites from biodegradation do not exert any negative biological effect. Technical aspects include the compatibility of pre- and posttreatment in a compost plant to the inclusion of bioplastics in the compost feedstock. The most important aspect is to schedule sieving at the end of the composting cycle.

Membrane Bioreactor for Control of Volatile Organic Compound Emissions

A membrane bioreactor system that overcomes many of the limitations of conventional compost biofilters is described. The system utilizes microporous hydrophobic hollow fiber membranes for mass transfer of volatile organic compounds (VOCs) from the gas phase to a microbially active liquid phase. The reactor design provides a high biomass concentration, a method for wasting biomass, and a method for addition of pH buffers, nutrients, cometabolites, and/or other amendments. A theoretical model is developed, describing mass transfer and biodegradation in the membrane bioreactor. Reactor performance was determined in a laboratory scale membrane bioreactor over a range of gas loading rates using toluene as a model VOC. Toluene removal efficiency was greater than 98% at an inlet concentration of 100 ppm\dv and a gas residence time of less than 2 s. Factors controlling bioreactor performance were determined through both experiments and theoretical modeling to include: compound Henry’s law constant, membrane specific surface area, gas and VOC loading rates, liquid phase turbulence, and biomass substrate utilization rate.

Changes in the Concentration of Soluble Anions in Compost During Composting and Mushroom (Agaricus bisporus) Growth

The changes in the concentration of nitrate, phosphate, chloride, sulphate, formate, acetate and oxalate anions extracted with water from conventional compost during composting and mushroom growth, and mushroom fruit bodies during cropping, were measured using an ion exchange chromatograph and a pulsed electrochemical detector. The addition of gypsum at Phase I in conventional composting dramatically increased the content of sulphate but lowered the content of oxalate (dry matter basis). Chloride in compost increased gradually during composting and mushroom growth probably due to its introduction in water used to irrigate the crop. Phosphate increased during the early stages of composting but decreased in spawning and fruit body formation. In fruit bodies, the relative content of boiling water extract decreased in successive flushes. Individual anions, acetate and oxalate increased steadily, phosphate and chloride decreased gradually and sulphate and nitrate first decreased steeply and then more slowly. Formate did not change. Phosphate, acetate, chloride and oxalate were higher in small buttons than in large buttons, but there were no differences for sulphate, nitrate or formate.

Compositional Changes in Compost during Composting and Growth of Agaricus bisporus

Samples from conventional compost taken at various stages of composting and mushroom (Agaricus bisporus) growth were analyzed for changes in 80% ethanol and water extracts, monosaccharides in acid hydrolysates of polysaccharides, lignin concentration, and lignin structural features. Variable amounts of extraneous inorganic solids in the form of fine sandy particles were removed by sedimentation of the samples in a carbon tetrachloride-dibromomethane mixture. During composting, about two-thirds of the initial wall polysaccharides were consumed by compost microorganisms, and only 17% of the total polysaccharides were used during mushroom production. The relative lignin content of composts as measured by the acetyl bromide procedure increased, both during composting and mushroom growth, and the chemical structure of lignin was altered by condensation and oxidation reactions.

Some critical comparisons of peat-sand and loam-based composts, with special reference to the interpretation of physical and chemical analyses

Some of the physical and chemical characteristics of the conventional loam-based composts for pot plants have been compared with those of composts made with peat and sand. The results indicate that because of the large differences in the volume-weights of these media, valid comparisons of the analytical results can only be made when they are expressed on a volume basis, rather than on the conventional weight basis. The importance of using the volume method increases as the volume-weight of the compost deviates from unity.