Emission of methane and carbon dioxide and earthworm survival during composting of pharmaceutical sludge and spent mycelia

Emissions of methane (CH4) and carbon dioxide (CO2) from spent mycelia of the mold Penicilium notatum and sludge from the effluent treatment facility (ETPS) of a pharmaceutical industry were estimated twice during a two-week composting before vermicomposting. These wastes are dumped in landfills or sometimes used in agricultural fields and no reports are available on their greenhouse gas producing potentials. The solid wastes contained appreciable organic carbon and nitrogen while very high Fe, Mn and Zn were found in ETPS only. Pure wastes did not support germination of Vigna radiata L. while mixing soil with ETPS and spent mycelia at the ratios of 12:1 and 14:1 led to 80% and 50% germination, respectively. The wastes were mixed with cowdung at the ratios of 1:1, 1:3 and 3:1 for composting. Carbon dioxide emissions were always significantly higher than CH4 emissions from all the treatments due to prevalence of aerobic condition during composting. From some treatments, CH4 emissions increased with time, indicating increasing activity of anaerobic bacteria in the waste mixtures. Methane emissions ranged from 21.6 to 231.7 microg m(-2) day(-1) while CO2 emissions were greater than thousand times at 39.8-894.8 mg m(-2) day(-1). The amount of C emitted as CH4-C and CO2-C from ranged from 0.007% to 0.081% of total C composted. Cowdung emitted highest CH4 followed by spent mycelia and ETPS while ETPS emitted more CO2 than spent mycelia but lesser than cowdung. Global warming potential of emitted CH4 was found to be in the range of 10.6-27.7 mg-CO2-equivalent on a 20-year time horizon. The results suggest that pharmaceutical wastes can be an important source of CH4 and CO2 during composting or any other stockpiling under suitable moisture conditions. The waste mixtures were found not suitable for vermicomposting after two weeks composting and earthworms did not survive long in the mixtures.     

Do earthworms affect dynamics of functional response and genetic structure of microbial community in a lab-scale composting system?

Two laboratory-scale systems were set up (i) composting (without earthworms) and (ii) vermicomposting (with earthworms) and were monitored for 60 days after pre-composting. The physico-chemical parameters (pH, C/N, organic matter, NH(4)(+)-N and ash content) showed similar evolution in both systems except a higher NH(4)(+)-N in the initial vermicomposts. However, principle component analysis (PCA) of enzymatic activities and community level physiological profiles revealed differences in the functional response of microbial communities in compost and vermicompost during maturation. Dehydrogenase activity and bacterial counts indicated a steady decrease in biological activity and population during composting, whereas vermicomposting exhibited higher activity on day 30 and a reduction in bacterial counts on day 10. PCA of denatured gradient gel electrophoresis (DGGE) profiles showed divergent dynamics of bacterial communities in two processes. These results indicated differences in the functional response and genetic structure of microbial community in composts and vermicomposts despite similar changes in their physico-chemical parameters.     

Effects of stocking density and feeding rate on vermicomposting of biosolids

The double-pronged problem of quantity, and disposal of waste streams from a myriad of industries, is becoming increasingly acute, the world over. The use of earthworms as a waste treatment technique for such wastes is gaining popularity. This method is commonly known as vermicomposting. Compared to conventional microbial composting, vermicomposting produces a product that is more or less homogenous, with desirable aesthetics, with reduced levels of contaminants and tends to hold more nutrients over a longer period, without impacting the environment. Like in other related waste treatment techniques, certain parameters need to be established for the design of efficient and economical vermicomposting systems. Specifically, the focus of this study was to investigate and establish an optimal stocking density and an optimal feeding rate for the vermicomposting of biosolids, with paper mulch provided as bedding. A stocking density of 1.60 kg-worms/m² (0.33 lb-worms/ft²) and a feeding rate of 1.25 kg-feed/kg-worm/day resulted in the highest bioconversion of the substrate into earthworm biomass. The best vermicompost was obtained at the same stocking density and a feeding rate of 0.75 kg-feed/kg-worm/day.     

Earthworms as vectors of Escherichia coli O157:H7 in soil and vermicomposts

Survival and movement of Escherichia coli O157:H7 in both soil and vermicompost is of concern with regards to human health. Whilst it is accepted that E. coli O157:H7 can persist for considerable periods in soils, it is not expected to survive thermophilic composting processes. However, the natural behavior of earthworms is increasingly utilized for composting (vermicomposting), and the extent to which earthworms promote the survival and dispersal of the bacterium within such systems is unknown. The faecal material produced by earthworms provides a ready supply of labile organic substrates to surrounding microbes within soil and compost, thus promoting microbial activity. Earthworms can also cause significant movement of organisms through the channels they form. Survival and dispersal of E. coli O157:H7 were monitored in contaminated soil and farmyard manure subjected to earthworm digestion over 21 days. Our findings lead to the conclusion that anecic earthworms such as Lumbricus terrestris may significantly aid vertical movement of E. coli O157 in soil, whereas epigeic earthworms such as Dendrobaena veneta significantly aid lateral movement within compost. Although the presence of earthworms in soil and compost may aid proliferation of E. coli O157 in early stages of contamination, long-term persistence of the pathogen appears to be unaffected.     

Composting and vermicomposting experiences in the treatment and bioconversion of asphaltens from the Prestige oil spill

This work illustrates the effectiveness of composting and vermicomposting in degrading fuel-in-water emulsions from oil spills (chapapote), and the isolation of potentially useful microorganisms for its biodegradation. Firstly, an alternative to the biodegradation of asphaltens from the Prestige oil spill (still present in some chapapote rafts in the Cantabrian coast) by means of the application of composting techniques to a microbial partnership acclimated to fuel-oil is offered. Our aim is that, after a relatively short period of time, the microorganisms can obtain its source of carbon and energy from asphaltens. The addition of metabolic co-substrates, like cow bed and potato peelings, allows the fragmentation of complex compounds into smaller structures, susceptible to further degradation. Afterwards, a maturation of the compost by means of a treatment with earthworms (Eisenia foetida) is necessary. Thus, through the vermicomposting it will be possible to obtain a valued product, useful in the processes of ground amendment, with little presence of asphaltens and occluded polycyclic aromatic hydrocarbons, rich in humus, and with an important bacterial flora of Bacillus genera, so that it can be typical of co-activators and accelerating products in composting processes. Along with this article, we show some parameters that control the evolution of the compost products (evolved gases, acidity, temperature and humidity); the chemical and microbiological analytical results; and the germination assays of vermicomposting. Results reveal that by using microorganisms living in either earthworm intestines (Stenotrophomonas maltophilia) or vermiculture substrates (Scedosporium apiospermium), it is possible to degrade and to eliminate the polycyclic asphaltens into CO(2) and H(2)O, helped by evaporation, dissolution and/or photo-oxidation processes. The obtained end product has contents of interesting vegetal nutrients and, mainly, it displays very high germination indices.     

Assessing the efficiency of urban waste biocomposting by analytical pyrolysis (Py-GC/MS)

Analytical pyrolysis (Py-GC/MS) was used to study complex composting processes. The technique was first validated for reproducibility and finally applied to assess the efficiency of a microbial bio-accelerator product (CBB) in composting organic residues with different composition. Fresh lignocellulosic and urban wastes were treated with CBB and the composting kinetics studied to investigate the transformations undergone in the course of biocomposting. Our findings demonstrate that these changes, as well as the efficiency of CBB, can be monitored through the molecular characterization of the released pyrolysis products. The CBB bacterial product effectively seems to favour composting accelerating the process and shorten composting time. Analytical pyrolysis was informative in assessing to which extent compost transformation reached an acceptable stabilization point. The technique could be also developed into a semi-quantitative tool to monitor changes of main organic matter components (polysaccharides, proteins, lignin, lipids, etc.) as composting proceeds.     

Composting of a crop residue through treatment with microorganisms and subsequent vermicomposting

Preliminary studies were conducted on wheat straw to test the technical viability of an integrated system of composting, with bioinoculants and subsequent vermicomposting, to overcome the problem of lignocellulosic waste degradation, especially during the winter season. Wheat straw was pre-decomposed for 40 days by inoculating it with Pleurotus sajor-caju, Trichoderma harzianum, Aspergillus niger and Azotobacter chroococcum in different combinations. This was followed by vermicomposting for 30 days. Chemical analysis of the samples showed a significant decrease in cellulose, hemicellulose and lignin contents during pre-decomposition and vermicomposting. The N, P, K content increased significantly during pre-decomposition with bioinoculants. The best quality compost, based on chemical analysis, was prepared where the substrate was treated with all the four bioinoculants together followed by vermicomposting. Results indicated that the combination of both the systems reduced the overall time required for composting and accelerated the composting of ligno-cellulosic waste during the winter season besides producing a nutrient-enriched compost product.     

Seed germination of the weed Rumex obtusifolius after on-farm conventional, biodynamic and vermicomposting of cattle manure

This study investigated whether composting methods differ in their impact on seed germination of Rumex obtusifolius (broad‐leaved dock). Weed seeds were buried in windrows of cattle farmyard manure, removed at monthly intervals and germinated during the course of 7 months. Composting methods differed in the maximum temperatures reached (63°C for conventional and biodynamic composting and 35°C for vermicomposting), the addition of 1000 m^?2 earthworms (Eisenia fetida) for vermicomposting and the inoculation of biodynamic preparations for biodynamic composting. After 1 month in windrows, germination rate of Rumex seeds was significantly higher in vermicompost (48%) than in conventional (28%) or biodynamic compost (18%). After 2 months in windrows, 26% of the seeds germinated in vermicomposting windrows, while those inserted in conventional and biodynamic windrows showed a negligible germination (0% and 2%, respectively). After 3 and 4 months, only seeds under vermicomposting germinated (22% and 3%, respectively). No germination was determined when seeds were inserted for longer than 4 months in any of the treatments. Seeds stored at room temperature germinated at 89% over the course of the experiment. Results suggest that the maximum temperature reached in windrows is not the single main factor reducing weed seed germination during composting.     

Suitability of aquaculture effluent solids mixed with cardboard as a feedstock for vermicomposting

Recirculating aquaculture systems are highly intensive culture systems that actively filter and reuse water, thus minimizing water requirements and creating relatively small volumes of concentrated waste (compared to flow-through aquaculture systems). Vermicomposting, which uses earthworms to stabilize and transform organic wastes into valuable end-products, has been proposed as an alternative treatment technology for high-moisture-content organic wastes from agricultural, industrial and municipal sources. This study was conducted to determine if the effluent solids from a large recirculating aquaculture facility (Blue Ridge Aquaculture, Martinsville, Virginia) were suitable for vermicomposting using the earthworm Eisenia fetida. In two separate experiments, worms were fed mixtures of solids removed from aquaculture effluent (sludge) and shredded. Mixtures containing 0%, 5%, 10%, 15%, 20%, 25%, and 50% aquaculture sludge (dry weight basis) were fed to the worms over a 12-week period and their growth (biomass) was measured. Worm mortality, which occurred only in the first experiment, was not influenced by feedstock sludge concentration. In both experiments worm growth rates tended to increase with increasing sludge concentration, with the highest growth rate occurring with feedstocks containing 50% aquaculture sludge. Effluent solids from recirculating aquaculture systems mixed with shredded cardboard appear to be suitable feedstocks for vermicomposting.     

Vermicomposting of different types of waste using Eisenia foetida: a comparative study

A study (100 days duration) was conducted to evaluate the efficiency of an exotic earthworm species (epigeic-Eisenia foetida) for decomposition of different types of organic substrates (kitchen waste, agro-residues, institutional and industrial wastes including textile industry sludge and fibres) into valuable vermicompost. The percentage of, nitrogen, phosphorous and potassium in vermicompost was found to increase while pH and total organic carbon declined as a function of the vermicomposting period. 4.4-5.8-fold increases in TKN was observed in different feed mixtures at the end of vermicomposting period. The increase in TKN for different feed substrates was found in the order: textile sludge>textile fibre=institutional waste>agro-residues>kitchen waste. Available Phosphorus increased 1.4 to 6.5-fold in different feed mixtures in comparison to control. Reduction in TOC was highest in agro-residues (3-fold) followed by kitchen waste (2.2-fold), institutional waste (1.7-fold) and textile industrial wastes (sludge, 1.5-fold and fibre, 1.68-fold) in earthworm-inoculated pots than control. The data reveals that vermicomposting (using E. foetida) is a suitable technology for the decomposition of different types of organic wastes (domestic as well as industrial) into value-added material.     

Municipal solid waste management through vermicomposting employing exotic and local species of earthworms

A comparative study was conducted between exotic and local (epigeic--Eisenia fetida and anaecic--Lempito mauritii, respectively) species of earthworms for the evaluation of their efficacy in vermicomposting of municipal solid waste (MSW). Vermicomposting of MSW for 42 days resulted in significant difference between the two species in their performance measured as loss in total organic carbon, carbon-nitrogen ratio (C:N) and increase in total Kjeldahl nitrogen, electrical conductivity and total potassium and weight loss of MSW. The change in pH and increase in number of earthworms and cocoons and weight of earthworms were non-significant.     

Microbial and decomposition efficiencies of monoculture and polyculture vermireactors,based on epigeic and anecic earthworms

Efforts have been made to evaluate the microbial and decomposition efficiency of three different vermireactors: (i) polyculture (introducing equal numbers of anecic and epigeic earthworms), (ii) monoculture (anecic) and (iii) monoculture (epigeic), designed by using earthworms of two different ecological categories i.e. anecic (Lampito mauritii Kinberg) and epigeic (Eisenia fetida (Savigny)). The microbial load of vermireactors was measured through substrate-induced respiration rate (SIR), microbial biomass N content and rate of dehydrogenase activity, while mineralization rate was evaluated measuring some chemical parameters of the substrate. Earthworms caused a decrease (as compared to initial value) in pH (41.9–80.7%), organic C (10.3–14.2%) and C:N ratio (41.9–80.7%) and an increase in total N (29.1–58.8%), NH₄-N (876.1–1485.7%), NO₃-N (29081.8–56792.6%), available P (16–19.4%) and exchangeable K (9.8–13.5%) contents of the substrate. The mineralization efficiency of the reactors was in the order: polyculture (epigeic + anecic) > monoculture (anecic) > monoculture (epigeic). The polyculture reactor showed the maximum rate of SIR (2.91 ± 0.2 mg CO₂ g⁻¹ substrate), microbial biomass N (3108.1 ± 289.2 mg N g⁻¹ substrate), and dehydrogenase activity (2453.3 ± 379.8 μg g⁻¹ substrate 24 h), while in the monoculture (epigeic) the lowest values of the same parameters were observed. It is concluded that the observed differences among reactors were due to different feeding behaviour and niche structures of epigeic and anecic earthworms. Data suggests that burrowing earthworms in waste-decomposing-system not only enhance the microbial efficiencies, but at the same time also accelerate the organic matter mineralization in a vermireactor. However, most of the previous studies were based on monoculture reactors (using epigeic earthworms) which have been recommended for waste decomposition operations, but this study revealed that polyculture vermicomposting (adding of burrowing worms with epigeic earthworms in vermicomposting system) might be beneficial for rapid decomposition of organic wastes.     

蚯蚓粪对黄瓜苗期土传病害的抑制作用

试验表明,蚯蚓对农业有机废弃物进行生物降解的产物－蚯蚓粪,在一定程度上能够控制蔬菜类黄瓜苗期土传病害的发生,并表现出明显的促生长效应,蚯蚓粪控制病害的程度与蚯蚓粪的量有一定的关系,当蚯蚓粪与土体积比为20％时,控制病的程度最大,防效达96．1％,这种作用主要与蚯 蚓粪中的微生物性质有关,蚯蚓粪能大大提高土壤中的微生物量和微生物活性,从而大大增强了病土中与病原菌进行能源竞争的微生物的竞争能力,同时从新鲜蚯蚓粪中成功分离到拮抗活性强,抗菌谱广的拮抗微生物,初步研究结果说明,一般性抑制和特殊性抑制两种机制在蚯蚓粪对病害的控制中起作用。     

Pilot-scale vermicomposting of pineapple wastes with earthworms native to Accra, Ghana

Pineapple wastes, an abundant organic waste in Accra, Ghana, were vermicomposted using native earthworms (Eudrilus eugeniae Kinberg) collected from the banks of streams and around bath houses of this city. Triplicate pilot-scale vermidigesters containing about 90 earthworms and three other control boxes with no earthworms were fed pineapple pulp or peels, and the loss of wet mass was monitored over 20 weeks. In a second experiment, a 1:1 mixture of pineapple peels and pulp (w/w) was fed to triplicate pilot-scale vermicomposters and control boxes during a 20 week period. One month after feeding ended, the vermicompost and composted (control) waste was air dried and analyzed. During the first experiment, the vermicomposted pineapple pulp and peels lost 99% and 87% of their wet mass, respectively, indicating the potential for vermicomposting. Fresh pineapple waste exhibited an initial pH of 4.4, but after 24 weeks, the vermicompost and compost had acquired a neutral to alkaline pH of 7.2–9.2. The vermicompost contained as much as 0.4% total N, 0.4% total P and 0.9% total K, and had a C:N ratio of 9–10. A reduction of 31–70% in the Escherichia coli plus Salmonella loads and 78–88% in the Aspergillus load was observed during vermicomposting. The rapid breakdown of pineapple wastes by E. eugeniae demonstrated the viability of vermicomposting as a simple and low cost technology recycling this waste into a soil amendment that could be used by the 2500 vegetable producers of Accra and its surrounding areas.     

Eisenia fetida (Oligochaeta, Lumbricidae) Activates Fungal Growth, Triggering Cellulose Decomposition During Vermicomposting

Cellulose is the most abundant polymer in nature and constitutes a large pool of carbon for microorganisms, the main agents responsible for soil organic matter decomposition. Cellulolysis occurs as the result of the combined action of fungi and bacteria with different requirements. Earthworms influence decomposition indirectly by affecting microbial population structure and dynamics and also directly because the guts of some species possess cellulolytic activity. Here we assess whether the earthworm Eisenia fetida (Savigny 1826) digests cellulose directly (i.e., with its associated gut microbiota) and also whether the effects of E. fetida on microbial biomass and activity lead to a change in the equilibrium between fungi and bacteria. By enhancing fungal communities, E. fetida would presumably trigger more efficient cellulose decomposition. To evaluate the role of E. fetida in cellulose decomposition, we carried out an experiment in which pig slurry, a microbial-rich substrate, was treated in small-scale vermireactors with and without earthworms. The presence of earthworms in vermireactors significantly increased the rate of cellulose decomposition (0.43 and 0.26% cellulose loss day⁻¹, with and without earthworms, respectively). However, the direct contribution of E. fetida to degradation of cellulose was not significant, although its presence increased microbial biomass (C_mic) and enzyme activity (cellulase and β-glucosidase). Surprisingly, as fungi may be part of the diet of earthworms, the activity of E. fetida triggered fungal growth during vermicomposting. We suggest that this activation is a key step leading to more intense and efficient cellulolysis during vermicomposting of organic wastes.     

Industrial wastes and sludges management by vermicomposting

Vermicomposting has been arising as an innovative ecotechnology for the conversion of various types of wastes into vermicompost. Vermicompost is humus like, finely granulated and stabilized material which can be used as a soil conditioner to reintegrate the organic matter to the agricultural soils. Industrial wastes remain largely unutilized and often cause environmental problems like ground and surface water pollution, foul odours, occupying vast land areas etc. Non-toxic and organic industrial wastes could be potential raw material for vermitechnology. In the last two decades, vermitechnology has been applied for the management of industrial wastes and sludges and to convert them into vermicompost for land restoration practices. The success of the process depends upon several process parameters like quality of raw material, pH, temperature, moisture, aeration etc., type of vermicomposting system and earthworm species used. The review discusses the vermitechnology and the present state of research in the vermicomposting industrial sludges and wastes.     

Prospects of using Metarhizium anisopliae to check the breeding of insect pest, Oryctes rhinoceros L. in coconut leaf vermicomposting sites

During vermicomposting of coconut leaves by the earthworm Eudrilus sp., Oryctes rhinoceros L. (rhinoceros beetle), an insect pest of palms, was found to breed in the decomposing organic material. Metarhizium anisopliae var. major was tried as a biocontrol agent for management of this pest. The effect of pathogen at spore loads of 10(3), 10(4) and 10(5) per 10 g of substrate was tested in laboratory on Eudrilus sp. kept with O. rhinoceros grubs and on Eudrilus sp. alone for the pathogenic capability of the fungus on the pest and its possible toxicity towards the vermin. The efficacy of the entomopathogen was also tested in the field in vermicomposting tanks. In laboratory bioassay, 100% mycosis of O. rhinoceros grubs could be obtained while the entomopathogen had no toxic effect on the earthworms. There was a positive change in the number and weight of the earthworms on treatment with M. anisopliae. In the field, application of M. anisopliae reduced O. rhinoceros grubs in the vermicomposting tanks upto an extent of 72%. In conclusion, M. anisopliae could effectively control O. rhinoceros in vermicomposting sites and was non-hazardous to the vermicomposting process as well as the Eudrilus sp.     

Biodegradation of olive husk mixed with other agricultural wastes

In this study, the evolution of the most important parameters (temperature, pH, electrical conductivity, total organic carbon, total nitrogen, and C/N ratio) describing the composting process of olive oil husk with other organic wastes was investigated. Four windrows for obtaining two mixed wastes composts (MWCs) and two green wastes composts (GWCs) were prepared.     

Recycling of organic wastes by employing Eisenia fetida

This paper reports the recycling of nutrients by vermicomposting of cow dung (CD), poultry droppings (PD) and food industry sludge (FIS) employing earthworms (Eisenia fetida). A total of six vermicomposting units were established and dynamics of chemical and biological parameters has been studied for 13 weeks. The waste mixture containing 50% CD+25% PD+25% FIS had better fertilizer value among studied waste combinations. At the end of experiment, vermicomposts showed decrease in pH and organic C, but increase in EC, total Kjeldhal N, total available P and total K contents. The C:N ratio of final vermicomposts also reduced to 10.7-12.7 from 22.8 to 56 in different waste combinations. The earthworms have good biomass gain and cocoon production in all vermicomposting units but CD alone and 50% CD+25% PD+25% FIS were better than other studied combinations.