The contamination of the environment with microplastic, defined as particles smaller than 5 mm, has emerged as a global challenge because it may pose risks to biota and public health. Current research focuses predominantly on aquatic systems, whereas comparatively little is known regarding the sources, pathways, and possible accumulation of plastic particles in terrestrial ecosystems. We investigated the potential of organic fertilizers from biowaste fermentation and composting as an entry path for microplastic particles into the environment. Particles were classified by size and identified by attenuated total reflection-Fourier transform infrared spectroscopy. All fertilizer samples from plants converting biowaste contained plastic particles, but amounts differed significantly with substrate pretreatment, plant, and waste (for example, household versus commerce) type. In contrast, digestates from agricultural energy crop digesters tested for comparison contained only isolated particles, if any. Among the most abundant synthetic polymers observed were those used for common consumer products. Our results indicate that depending on pretreatment, organic fertilizers from biowaste fermentation and composting, as applied in agriculture and gardening worldwide, are a neglected source of microplastic in the environment.
Previous studies indicated that the quality of tropical composts is poorer than that of composts produced in temperate regions. The aim of this study was to test the type of manure, the use of co-composting with green waste, and the stabilization method for their ability to improve compost quality in the tropics. We produced 68 composts and vermicomposts that were analysed for their C, lignin and NPK contents throughout the composting process. Bayesian networks were used to assess the mechanisms controlling compost quality. The concentration effect, for C and lignin, and the initial blend quality, for NPK content, were the main factors affecting compost quality. Cattle manure composts presented the highest C and lignin contents, and poultry litter composts exhibited the highest NPK content. Co-composting improved quality by enhancing the concentration effect, which reduced the impact of C and nutrient losses. Vermicomposting did not improve compost quality; co-composting without earthworms thus appears to be a suitable stabilization method under the conditions of this study because it produced high quality composts and is easier to implement.
The fate of chlortetracycline (CTC), sulfadiazine (SDZ) and ciprofloxacin (CIP) during composting of swine manure and their effect on composting process were investigated. Swine manure was spiked with antibiotics, mixed with saw dust (1:1 on DW basis) and composted for 56d. Antibiotics were spiked to a final concentration of 50mg/kg CTC+10mg/kg SDZ+10mg/kg CIP (High-level) or 5mg/kg CTC+1mg/kg SDZ+1mg/kg CIP (Low-level), and a control without antibiotics. Antibiotics at high concentrations delayed the initial decomposition that also affected the nitrogen mineralization. CTC and SDZ were completely removed from the composting mass within 21 and 3d, respectively; whereas, 17-31% of the spiked CIP remained in the composting mass. Therefore, composting could effectively remove the CTC and SDZ spiked even at high concentrations, but the removal of ciprofloxacin (belonging to fluoroquinolone) needs to be improved, indicating this antibiotic may get into the ecosystem through land application of livestock compost.
Parascaris equorum generally infects horses less than 18 months old and its pathological effects can be severe. Infection occurs when larvated eggs, present in pastures, paddocks, stalls, and on feeding and watering equipment are ingested. The purpose of this study was to examine the effects of windrow composting on the viability of P. equorum eggs at a cooperating central Kentucky horse farm. Three grams of feces containing 2216 P. equorum eggs per gram were sealed in filter bag sentinel chambers. Chambers were exposed to 1 of 3 treatments: constant exposure or intermittent exposure to the interior of the windrow; controls were stored at 4°C. At day 0, all chambers in the experimental treatments were placed in the center of 10 locations of the windrow. On subsequent days when the windrow was turned, chambers in the constant exposure treatment were returned to the interior of the windrow and chambers in the intermittent exposure treatment were alternated between resting on top of, or inside, the windrow. Chambers from each treatment and control chambers were removed at days 2, 4, 6, 8, 10, 12, 14, and 18; and incubated for 21 days at room temperature (24°C). After incubation, eggs were recovered from the chambers using double centrifugation flotation. Eggs were evaluated microscopically, staged according to development and classified as viable or nonviable based on whether embryonation to the larval stage had occurred. Results were reported as the mean percent viable eggs for each treatment and time point. A mixed linear model with repeated measures was used to evaluate the influence of experimental day and treatment on the percent viability of P. equorum eggs. Chambers treated with constant exposure contained 10.73% (SD=0.29) viable eggs on day 2 and declined to an average of 0.00% by day 8. Chambers exposed to the intermittent treatment contained 16.08% (SD=0.26) viable eggs on day 2 and decreased to 0.00% by day 6. Control chambers for days 2, 4, 6, 8, 10, 12, 14, and 18 all had viabilities above 79.00%. A significant fixed effect of experimental day (p<0.0001) and compost treatment (p<0.0001) was observed. There was no significant interaction between experimental day and compost treatment (p>0.7459). The results of this study demonstrate that windrow composting was effective at rendering P. equorum eggs nonviable when it was tested under the conditions at a working horse farm.
This study sought to evaluate the efficacy of aerobic and anaerobic composting of inoculated banana peels, and assess the agronomic value of banana peel-based compost. Changes in the chemical composition under aerobic and anaerobic conditions were examined for four formulations of banana peel-based wastes over a period of 12weeks. The formulations i.e. plain banana peel (B), and a mixture with either cow dung (BC), poultry litter (BP) or earthworm (BE) were separately composted under aerobic and anaerobic conditions under laboratory conditions. Inoculation with either cow dung or poultry litter significantly facilitated mineralization in the order: BP>BC>B. The rate of decomposition was significantly faster under aerobic than in anaerobic composting conditions. The final composts contained high K (>100gkg(-1)) and TN (>2%), indicating high potential as a source of K and N fertilizer.
Composting facilities in Thailand have faced various operational problems, resulting in the emission of odours, incomplete digestion of waste organics, and higher than desired costs. Composting technologies imported from developed countries tend to be sized for larger communities and are otherwise not suited for the rural communities that comprise more than 80% of all communities in Thailand. This article addresses the research and development of a novel composting technology aimed at filling this observed need. The study was divided into two parts: (1) the development of a new composting technology and fabrication of a prototype configuration of equipment; and (2) scale-up and study on a pilot-scale using real rubbish. The proposed technology, called ‘serial self-turning reactor (STR)’, entailed a vertical flow composting system that consisted of a set of aerobic reactors stacked on a set of gravity fed turning units. In-vessel bioreactor technology enables the operator to control composting conditions. The researchers found that a tower-like STR results in flexibility in size scale and waste processing residence time. The pilot-scale experiments showed that the proposed system can produce good quality compost while consuming comparatively little energy and occupying a compact space, compared to traditional land-intensive windrow composting facilities.
Experiments were conducted to remove heavy metals (Cr, Cd, Pb, Cu and Zn) from urban sewage sludge (SS) amended with spent mushroom compost (SMC) using worms, Lumbricus rubellus, for 105 days, after 21 days of pre-composting. Five combinations of SS/SMC treatments were prepared in triplicate along with a control for each treatment in microcosms. Analysis of the earthworms' multiplication and growth and laboratory analysis were conducted during the tenth and fifteenth week of vermicomposting. Our result showed that the final biomass of earthworms (mg) and final number of earthworms showed significant differences between treatments i.e. F=554.70, P=0.00 and F=729.10, P=0.00 respectively. The heavy metals Cr, Cd and Pb contained in vermicompost were lower than initial concentrations, with 90-98.7percent removal on week ten. However, concentrations of Cu and Zn, that are considered as micronutrients, were higher than initial concentrations, but they were 10-200-fold lower than the EU and USA biosolid compost limits and Malaysian Recommended Site Screening Levels for Contaminated Land (SSLs). An increment of heavy metals were recorded in vermicompost for all treatments on week fifteen compared to week ten, while concentration of heavy metals in earthworms' tissue were lower compared to vermicompost. Hence, it is suggested that earthworms begin to discharge heavy metals into their surroundings and it was evident that the earthworms' heavy metals excretion period was within the interval of ten to fifteen weeks.
The efficiency of home composting programmes and the quality of the produced compost was evaluated in eight rural areas carrying out home composting programmes (up to 880 composting bins) for all household biowaste including meat and fish leftovers. Efficiency was analysed in terms of reduction of organic waste collected by the municipal services. An efficiency of 77% on average was obtained, corresponding to a composting rate of 126kg/person·year of biowaste (or 380kg/composter·year). Compost quality was determined for a total of 90 composting bins. The operation of composting bins by users was successful, as indicated by a low C/N ratio (10-15), low inappropriate materials (or physical contaminant materials, mean of 0.27±0.44% dry matter), low heavy metal content (94% of samples met required standards for agricultural use) and high nutrient content (2.1% N, 0.6% P, 2.5% K, 0.7% Mg and 3.7% Ca on average, dry matter). The high moisture (above 70% in 48% of the samples) did not compromise the compost quality. Results of this study show that home composting of household organic waste including meat and fish leftovers is a feasible practice. Home composting helps individuals and families to reduce the amount of household waste at the same time gaining a fertiliser material (compost) of excellent quality for gardens or vegetable plots.
Compost production is a critical component of organic waste handling, and compost applications to soil are increasingly important to crop production. However, we know surprisingly little about the microbial communities involved in the composting process and the factors shaping compost microbial dynamics. Here, we used high-throughput sequencing approaches to assess the diversity and composition of both bacterial and fungal communities in compost produced at a commercial-scale. Bacterial and fungal communities responded to both compost recipe and composting method. Specifically, bacterial communities in manure and hay recipes contained greater relative abundances of Firmicutes than hardwood recipes with hay recipes containing relatively more Actinobacteria and Gemmatimonadetes. In contrast, hardwood recipes contained a large relative abundance of Acidobacteria and Chloroflexi. Fungal communities of compost from a mixture of dairy manure and silage-based bedding were distinguished by a greater relative abundance of Pezizomycetes and Microascales. Hay recipes uniquely contained abundant Epicoccum, Thermomyces, Eurotium, Arthrobotrys, and Myriococcum. Hardwood recipes contained relatively abundant Sordariomycetes. Holding recipe constant, there were significantly different bacterial and fungal communities when the composting process was managed by windrow, aerated static pile, or vermicompost. Temporal dynamics of the composting process followed known patterns of degradative succession in herbivore manure. The initial community was dominated by Phycomycetes, followed by Ascomycota and finally Basidiomycota. Zygomycota were associated more with manure-silage and hay than hardwood composts. Most commercial composters focus on the thermophilic phase as an economic means to insure sanitation of compost from pathogens. However, the community succeeding the thermophilic phase begs further investigation to determine how the microbial dynamics observed here can be best managed to generate compost with the desired properties.
Feedstock composition influences vermicomposting performance of Dichogaster annae relative to Eudrilus eugeniae and Perionyx excavatus
- Environmental science and pollution research international
- Published 10 months ago
Carbon to nitrogen (C/N) ratio influences substrate combinations and earthworm performance in vermicomposting systems. To elucidate these factor effects, a comparative evaluation of species, C/N ratio combined with feed rate, was conducted on three local earthworm species: Perionyx excavatus, Eudrilus eugeniae, and Dichogaster annae. Earthworms were stocked at similar densities and fed shredded paper (SP), cattle manure (CM), and lawn clippings (LC) combined to form C/N ratios of 28, 36, and 53. Earthworms were fed at rates of 1, 1.25, and 2 g feed (dry wt.)/g worm/day for a period of 8 weeks. Percent vermiconversion, earthworm adult and juvenile biomass, and vermicast quality were measured. Vermicast production was significantly affected by the combination of C/N ratio and feed rate and varied among species. All treatment combinations resulted in > 70% conversion, except E. eugenaie fed at the medium rate. Vermiconversion increased for P. excavatus and D. annae with increasing C/N ratio but decreased with increasing the feed rate. Vermicast EC, pH, and C/N ratio was strongly affected by species, relative to other experimental factors. D. annae showed the greatest change in biomass, which peaked at the highest feed rate and lowest C/N ratio. Average adult biomass decreased for P. excavatus with increasing feed rate, while differences were nonsignificant for E. eugenaie and D. annae. Significant increases in average juvenile biomass were only evident for D. annae in response to increasing feed rates. Feed rate had a greater influence on earthworm population dynamics and vermicast quality compared to initial feedstock C/N ratio.