Compost Production Research Articles

Manganese dioxide eliminates the phytotoxicity of aerobic compost products and converts them into a plant friendly organic fertilizer

This study mainly confirmed the exogenous substances (pomace, biochar, MnO2) and the quorum sensing of bacterial communities jointly regulate the metabolic conversion of toxic substances in manures and agricultural wastes, and converts them into a plant-friendly organic fertilizer through aerobic composting and pot experiment. The results showed the composting products had positive performance in bacterial communities, physicochemical indicators, and phytotoxicity. Meanwhile, the addition of exogenous substances could significantly improve seed germination index, promote metabolites conversion, and optimize bacterial community structure. Furthermore, the exogenous substances mainly regulated the functions of the three bacterial communities by quorum sensing system, then promoted the beneficial metabolites, and inhibited the harmful metabolites. Finally, pot experiments suggested compost products could significantly promote plant growth. Thus, these important discoveries extend the knowledge of the previous work and provide an economical and simple method to convert wastes into organic fertilizers that are friendly to plants and soil.

Biodegradación del plástico con larvas de insecto Tenebrio molitor como contribución interdisciplinar a la biotecnología a la biotecnología medioambiental

Pollution is the greatest human impact on the planet, that is, the environment is made up of natural and artificial elements, their physical, chemical, biological, social and cultural activities and their respective relationships. The objective of this investigation was to analyze the biodegradation of plastics, from larvae of the Tenebrio molitor beetle, as a contribution to the teaching of environmental biotechnology. Basically, the execution of this project was based on 3 stages. The characterization of Tenebrio molitor larvae, the rearing of the larvae and the quantification of the capacity to biodegrade plastic. The results obtained were, they found that sample 1 (M1) had a specific biomass productivity of 6.6 grams while sample 2 (M2) a specific productivity of 2.3 grams was recorded and managed to show a change in terms of color and the amount of feces. Finally, the biodegradation of polystyrene influences the production of compost, benefiting the consumption of plastic.
 keywords : Biodegradation, Plastic, Tenebrio molitor, Environmental biotechnology, larvae.

Assessing Physiochemical Characteristics of Agricultural Waste and Ready Compost at Wadi Al-Far'a Watershed of Palestine.

The Wadi Al-Far'a Watershed (WFW) is one of the most important agricultural lands in Palestine where considerable amounts of organic wastes are generated. Yet, mismanagement of agricultural waste, including random disposal and/or burning, is a prevalent practice in the WFW. Such a practice might result in greenhouse gas emissions and leachate penetration into underlying soil and groundwater. To encourage compost production in the WFW as an efficient way for organic agricultural waste treatment and emission reduction, this study aims at evaluating the quality of both raw organic agricultural waste and ready compost, locally produced or imported. The evaluation considers the physiochemical characteristics as well as the heavy metal contents. The analysis of 17 samples of raw organic agricultural waste showed a good potential for compost production due to the high content of organic matter and other nutrients such as nitrogen and phosphorus. The analysis of 15 ready compost samples, however, showed that compost quality is relatively low due to the high electrical conductivity and low moisture content measurements as well as the high levels of sodium, chloride, and potassium. Furthermore, heavy metal contents of both raw organic agricultural waste and ready compost samples are less than the limits specified by the Palestinian and international standards. Therefore, local farmers can safely use raw organic agricultural waste generated in the WFW for compost production. Composting will not only enhance soil reclamation and crop production but also protect human health and the environment and promote sustainable economic development.

Silage and flue gas desulfurized gypsum as additives improve green waste composting

Although composting is an environmentally safe and efficient way to dispose of and stabilize green waste (GW), the composting of GW generally takes a long time due its high lignocellulose content. To reduce the composting period and increase compost quality, an L9 (34) orthogonal experiment was conducted to assess the effects of silage (SG; 0, 25, 45 %) and flue gas desulfurization gypsum (FGDG; 0 %, 2.5 %, and 5 %) as additives on GW composting. Treatments differed in the quantities of SG and FGDC added, but all treatments received the same quantities of urea (24 g per kg of GW dry weight) and microbial inoculum (5 ml per kg of GW dry weight) at the start of the composting process. The results indicated that the addition of SG or/and FGDG accelerated the composting process and increased the maturity and nutrient contents of the compost product. According to a multi-index matrix analysis, the optimal combination of SG and FGDG was 45 % SG and 2.5 % FGDG. The optimal treatment resulted in a compost product with a coarseness index of 35.47, a germination index of 263 %, and the following contents (mg/kg) of total Kjeldahl nitrogen, total phosphorus, total potassium, NO3--N, available phosphorus, and available potassium: 35,634, 10,937, 13,243, 13.27, 143.51, and 8873.36, respectively. The optimal combination of SG and FGDG reduced the composting of GW to 28 days and produced a stable and high-quality compost product.

Insights on Harnessing Domestic Biowaste for Greening the Green City of Benguerir in Morocco

As the human population grows, the amount of household-generated waste is projected to grow. However, data on the amounts of household-generated waste are lacking in many regions. Uncertainties in the amounts and fractions of biowaste make it challenging to manage actions that reduce its environmental impacts and generate value. The current observational study sought to quantify and characterize the household waste generated in the green city of Benguerir. To achieve this objective, we surveyed waste generation rates in 68 randomly selected households. The results showed that, on average, 0.69 kg of waste was generated per person per day. An average of 80% of the household-generated waste was biowaste, which, if managed appropriately, represents a valuable source of plant nutrients. We estimated that shifting from the current landfill disposal of biowaste to its utilization for compost and biogas production will result in up to an 88% reduction in greenhouse gas emissions. These findings suggest that managing household waste will be vital for reducing city-wide carbon emissions and simultaneously creating employment in the waste management sector.

Review on Aquatic Weeds as Potential Source for Compost Production to Meet Sustainable Plant Nutrient Management Needs

As a result of the increase in agricultural production and environmental pollution, waste management and disposal are becoming vital. Proper treatments, such as converting abundant bio-mass wastes into beneficial materials, might mitigate the negative effects and convert waste into reusable resources. Aquatic weeds are a significant concern in the majority of water bodies. Their quick growth, rapid ecological adaptations, and lack of natural enemies make these plants invasive, problematic, and challenging to manage over time. Although there are many methods to manage aquatic weeds, composting has been identified as one of the easily adapted and eco-friendly methods for transferring nutrients to the cropping cycle. Their short life cycle, higher biomass yield, higher nutrient compositions, and allelopathic and phytoremediation properties confirm their suitability as raw materials for composting. Most aquatic ecosystems can be maintained in optimum conditions while facilitating maximum benefits for life by identifying and developing proper composting techniques. Studying the ecology and morphological features of aquatic weeds is essential for this purpose. This is an overview of identifying the potential of aquatic weeds as a source of composting, targeting sustainable plant nutrient management while managing weeds.

Degradation of acetochlor in soil by adding organic fertilizers with different conditioners

Adding compost to degrade acetochlor in soil is an important way to reduce its impact on the environment. The addition of conditioner improved the generation of compost products with specific effects. Thus, in order to determine a better composting conditioner for degradation of acetochlor, the dissipation of acetochlor in unmodified and different composting conditioners (zeolite, biochar, zeolite + biochar) was studied by pot experiment. The effects of residual concentrations of acetochlor (1.02, 1.56 and 2.08 mg·kg−1) and soil types (phaeozem and stagnic soil) on the dissipation of acetochlor were evaluated. The community structure of microbial fungi and bacteria in soil was determined by high-throughput sequencing to evaluate the change of microbial community in the soil with acetochlor residue. The results showed that compost types, soil types and the concentration of acetochlor residue in soil had different effects on the dissipation of acetochlor in soil. The addition of biochar and zeolite could significantly increase the degradation rate of acetochlor in soil. When the same compost was added, the degradation of acetochlor was fastest in phaeozem with a degradation rate of 95.13%. The degradation rate of acetochlor in black soil was higher than that in stagnic soil. High throughput sequencing results showed that the application of organic fertilizer changed the structure of soil microbial community. Luteibacter, Sagenomella and Remersonia had the highest correlation with the degradation of acetochlor in soil. The analysis of microbial community showed that·Luteibacter (24.49%),·Sagenomella (1.55%) and Remersonia (3.14%) played important roles in the degradation of acetochlor. Artificial neural network analysis showed that the sensitivity of acetochlor degradation rate to the conditioner in the soil was biochar (60.07%) > biochar + zeolite (21.19%) > blank (13.97%) > zeolite (4.77%). These results showed that biochar compost was more conducive to the dissipation of acetochlor in soil after application, and the application of organic fertilizer affected the soil microbial community structure.

Composting pig manure with nano-zero-valent iron amendment: Insights into the carbon cycle and balance

The effectiveness of nano-zero-valent-iron (NZVI) addition during composting of pig manure (PM) was investigated. Different dosages of NZVI were mixed with PM substrate during a 50 days composting process. The results revealed that the higher share of NZVI addition, the higher OM degradation rate is. On contrary, it was observed that the higher share of NZVI addition, the lower the fulvic acid and the humin degradation rate is. Meanwhile, NZVI amendment increased the CO2 and CH4 emissions by 29–47 % and 53–57 %, respectively. The in-depth analysis showed that NZVI addition increased the activity of Sphaerobacter and Luteimonas, which eventually led to the degradation of hard-to-degrade OM faster. Additionally, NZVI was found to increase the filtration of microorganisms, reducing the toxicity and hygiene of compost products. No significant improvement in humic substance enhancement was observed during composting with NZVI addition but improved OM degradation.

Prediction compost criteria of organic wastes with Biochar additive in in-vessel composting machine using ANFIS and ANN methods

In-vessel composting machine with the agitating system, circulating aeration system, and heating system on vegetable and food waste with coco peat additives and biochar obtained from coco peat was investigated. The composting process was tested at 55 °C, at three fresh inlet air rates of 20%, 30%, and 50%, three initial carbon-to-nitrogen (C/N) ratios of 18, 22, 26, and the addition of coco peat biochar of 5%, 10% w.b. (wet basis). To predict compost evaluation indicators of Electrical conductivity (EC), pH, C/N & GI, artificial neural network (ANN), and neural-fuzzy inference systems were used. The evaluation of the output parameters of compost showed high efficiency of the process. The amount of EC, acidity, and GI increased for all treatments, and the C/N ratio decreased. Also, the initial C/N ratio of 22 and fresh inlet air (FIA) of 30% were considered as the optimal setting conditions of the device. Treatment containing 5% biochar in the C/N of 22 resulted in the highest germination index of 93.55%. The best values of the coefficient of determination for the output parameters of the compost production process (EC, pH, C/N & GI) in the artificial neural network were 0.9252, 0.9863, 0.9691, and 0.9909 respectively. Moreover, the best values of the coefficient of determination in the fuzzy neural inference system for the output parameters of the compost include EC, pH, C/N and GI were 0.999, 0.999, 0.994, and 0.992, respectively. Also, the lowest values of MAE and RMSE in the fuzzy neural inference system for the output parameters of the compost include EC, pH, C/N, and GI were 0.0308, 0.0001, 0.2420, and 0.003 for MAE; and 0.0021, 3.66E−05, 0.1908 and 0.0041 for RMSE, respectively.

Composting of limed fleshings generated in a tannery: sustainable waste management.

In tanneries, limed fleshing is an unavoidable waste generated in beamhouse operation. Proper management of limed fleshing with protein, fat, lime, and sulfide will help to protect the natural environment and at least reduce the pollution that ends up in it. In this study, excluding any pretreatment, limed fleshing is used for compost production. Chopped and mixed limed fleshing with chicken manure, cow dung, and sawdust was heaped onto a horizontal bamboo frame. Three composting heaps were fabricated weighing 720, 700, and 760kg. The turning of composting materials in the heaps causes temperature changes in the thermophilic range. The thermophilic temperatures in these heaps were 69.07°C (heap 1), 69.9°C (heap 2), and 69.19°C (heap 3) which ensured the death of the pathogenic organism. The quality of compost was assessed based on the nutrients-nitrogen (N), phosphorous (P), potassium (K), and sulfur (S) content. NPKS in the compost fulfils the requirements of the investigated materials as compost. The largest amounts of metals- zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), and nickel (Ni) of the compost detected in the heaps were, respectively, 200.3, 37.4, 20.3, 12.0, and 3.9mg/kg. Cadmium (Cd) in the compost was below the detection limit. Scanning electron microscope (SEM) photographs show the decomposing of composting materials. This study indicates that limed fleshing can be converted into nutrient-enriched compost without any pretreatment. Using an easy, simple, and adaptable technique could reduce the volume of solid waste generated in the tannery to reduce environmental pollution.

Effect of biochar addition on copper and zinc passivation pathways mediated by humification and microbial community evolution during pig manure composting

The mobility and bioavailability of Cu and Zn are the main threats associated with the land application of pig manure (PM) compost products. This study investigated the impacts of biochar (BC) concentration on passivation of Cu and Zn associated with the compost maturity. The results indicated that 15% and 10% BC favoured the passivation of Cu and Zn, respectively. BC promoted passivation of Cu by accelerating HA production and optimized the abundance of Firmicutes. BC promoted the passivation of Zn by increasing the high temperature peak and the corresponding pH (8–8.5). A higher level (15% and 20%) of BC altered the dominant bacterial phylum from Firmicutes to Proteobacteria. 20% BC inhibited the passivation of Cu and Zn by reducing the highest temperature and lowering the alkalinity of substrate. These results offer new insights into understanding how the addition of BC could reduce the risk of hazardous products during PM composting.

Impact of Storage Time on the Composition of a Finished Compost Product: A Case Study

Highlights The concentrations of major plant nutrients, key minor plant nutrients, and carbon were measured for finished turkey poult litter compost that had been stored for 29 to 583 days in open windrows at a commercial composting facility. It was found that the concentrations of TN, P2O5, K2O, and minor plant nutrients were not significantly correlated with respect to compost age. Significant negative correlations were observed for the concentrations of organic matter and carbon resulting in a decrease in C:N. Significant decreases in compost pH and increases in bulk density were also observed. Abstract. Several studies have provided information concerning the loss of nitrogen, phosphorous, potassium, carbon, and organic matter from manures and plant residues during active composting. However, very little information was found to provide insight into the changes in compost composition as the product ages during curing and storage in uncovered windrows. The objective of this study was to observe changes in compost composition after it was removed from a composting shed and was stored in large un-covered windrows at a compost production site that used turkey poult litter (manure and wood shavings) as the primary ingredient. Compost samples and production records were obtained for 7 windrows and it was determined that the active composting time under the shed (AC) averaged 99 days and the time allowed for curing and storage in the uncovered windrows (CS) ranged from 29 to 583 days. As a result, the total compost age (CA = AC + CS) at the time of sampling ranged from 131 to 674 days. The quantities measured were moisture, pH, bulk density, electrical conductivity (EC), carbon (C). organic matter (OM), total ammoniacal N (TAN = NH4+-N + NH3-N), nitrate-N, organic-N, total-N (TN), P2O5, K2O, Ca, Mg, S, Zn, Cu, Mn, Fe, Na, and Al. The TN content was not found to change significantly while being stored in the outside windrows. However, the TAN content decreased significantly with storage time while nitrate-N and organic-N concentrations increased. The results showed evidence of nitrification of ammonium-N and a build-up of organic-N during storage. Storage time did not significantly impact concentrations of P2O5, K2O, Al, Na, and all minor plant nutrients measured. The pH fell from 8.9 at a compost age of 131 days to a mean of 6.8 by day 363 providing evidence of formation of organic acids during storage. Significant decreases during storage were observed for C, OM, and C:N. The rate of organic matter loss during storage was -0.623 g OM/kg DM/day and carbon was lost at the rate of -0.447 g C/kg DM/day. The electrical conductivity was not correlated with storage time and the mean was 3.80 ± 3.25 mmhos/cm. The bulk density increased significantly during curing and storage (R2 = 0.693) and was believed to be the result of compression settling. Keywords: Compost, Manure Management, Plant nutrients, Treatment.

Виробничі комплекси машин для аерації при компостуванні органічної сировини

The purpose of the research is to generalize the selection of machines and equipment to ensure mechanized composting processes using the example of the mixture aeration operation. Research methods: systematic analysis of technological methods, technical and economic characteristics of means for mechanized composting. The organizational factors influencing the choice of mobile technical means and stationary equipment in the production of composts are determined. A mechano-technological model scheme was developed, which determines the possible options for choosing equipment. The selection efficiency criteria are the costs and energy intensity of the technological cycle from obtaining raw materials to use, subject to the provision of sanitary and veterinary permits and the terms of operations. Benefits have results with minimum values. Considered methods of aeration with forced compressed air and mobile devices of mechanical action. Advantages and disadvantages are defined. Calculations of the theoretical productivity of mobile aerators - mixers were carried out, taking into account the volume of raw materials and the periodicity of processing. Options for choosing technical solutions with a minimum number of technical means are offered. The choice of technical means of aeration of the compostable mixture must be carried out taking into account the periodicity of the processing cycle. The use of an organic fertilizer spreader (similar to PRT-10(7)), trailed, self-propelled aerators - mixers, improved for the processes of composting raw materials, allows to reduce the number of technical means used in mechanized composting technology and increase economic efficiency.

Anaerobic Digestion and Composting as Methods of Bio-Waste Management

Abstract The management of biodegradable waste from various sectors of economy is an essential element in terms of environmental protection. The paper discusses issues related to the possibility of bio-waste treatment using anaerobic digestion technologies and composting processes, highlighting the conditions for the processes and their advantages and disadvantages. The challenges of overproduction of bio-waste faced by highly developed countries around the world are also presented. Research showed that the anaerobic digestion of this waste combines both biofuel production and a circular economy. The popularity of this method is linked, among others to a low cost of raw materials and wide range of possible uses for biogas (i.e. electricity, heat, or biomethane). In addition, an alternative bio-waste management option, compost production, was discussed. The study aimed to compare anaerobic and aerobic bio-waste management processes.

Модернізація розкидача органічних добрив «ПРТ-10» для використання в технології механізованого компостування

The purpose of the work is to present the results of testing mock-up samples of technical devices and equipment for the «PRT-10» organic fertilizer spreader to ensure that they fulfill the functional capabilities of mechanized composting and meet the requirements of the technological regulations. Methods and materials. To form a shoulder width of 2.5-3.5 m, a modernized spreader of organic fertilizers of the «PRT-10» type with replaceable drum-milling working bodies was used. Mock-up samples of the working bodies proposed by the author were installed at the places of installation of the existing drums, the main structural difference of which is the presence of right and left spiral lines. The blade installations are directed toward each other, which ensures the movement of raw materials from the side walls to the middle of the container. At the same time, the design of the drive of the working bodies did not change. Results. One of the options for increasing the efficiency of compost production is the expansion of technological capabilities and the development of additional technical devices and equipment for the spreader of organic fertilizers «PRT-10». The design of the mechanized composting device proposed by the author is a separate replaceable module installed on the rear board at the location of two drums of the «PRT-10» serial device. The main purpose of the replaceable module is pre-grinding, mixing of components, and formation of the edge during the preparation of a multi-component mixture that accumulates in the spreader trailer in the technology of mechanized composting. The use in the construction of the «PRT-10» serial spreader of interchangeable drums with the right and left directions of blade installation provides the technological height of the formed edge up to 1.6-1.7 m. The width of the base of the edge is 2.5-3.0 m, which agrees with the basic width values captured by aerators-mixers. The productivity of the unloading tool is up to 100 t/h. A special device for moistening mixtures with a moisture content of 30-45% ensures the introduction of water up to 40-60 l/t. Calculations carried out by the author on the use of the modernized spreader of organic fertilizers «PRT-10» and the aerator-mixer «AZK-2» in the production of composts proved economic advantages in the form of a reduction in fuel consumption during 4 cycles of aeration of the mixture – by 2.5 times. Conclusions. The use of a modernized device on transport units makes it possible to reduce the number of technical means involved in auxiliary operations of mechanized composting. Compost production using the modernized «PRT-10» spreader is economically feasible in existing economic conditions up to 2.0-2.2 thousand tons per processing season. For larger volumes, it is more appropriate to use the «AZK-2» trailed aerator mixer. Key words: compost mixture, burt, modernized spreader, replaceable drum, attached device, moistening, straw layer, mixing, grinding.

Enhancement of availability of high calcareous phosphorite by neutralization of acid effluent and composting of cattle manure

In this article, the influence of acidic effluent (AE) neutralization process, the production of raw fatty acids of cotton soap stock, on the change in the applicability of phosphate powder (PP) and mineralized mass (MM), which are low-grade phosphorites of the Central Kyzylkum, has been studied. It was found that with wide changes in the mass ratios of AE : PP and AE: MM (from 100:10 to 100:40) at a temperature of 60 °C and a time duration of 30 min, the content of the relative assimilable forms of phosphorus in 2% citric acid are approximately from 1.95 to 1.63 and from 3.67 to 1.72 folds more with a content of 17.52 and 9.11% of the assimilable form of P2O5 for citric acid PP and MM respectively. Activated phosphorite obtained at a mass ratio of AE: PP and AE: MM = 100:20 was introduced into cattle manure at various mass ratios from 100:8 to 100:20 for composting for 3 months. The prepared mixture was moistened periodically with water to a moisture content of 65-70%. It has been established that with an increase in the content of activated phosphorite and the duration of composting time, it leads to an increase in the content of humic acids, fulphonic acids, and water-soluble organics in the compost products. On the other hand, the duration of composting tends to increase the degree humification above 60%. The approach of acid treatment and composting of carbonate phosphorites can be included as a promising technology for obtaining effective organomineral fertilizers for creating an organic garden in agriculture.

Conservation Analysis of Food Waste Composting: Insight from the Nutrient Content and Compost Quality Index (CQI) Assessment

Compost has a critical role in preserving and conserving soil health and increasing soil fertility, both of which are essential for sustainable agricultural systems. The purpose of this research was to evaluate the efficacy of effective microorganisms (EM) in composting vegetable waste (VW), fruit waste (FW), and mixed food waste (MFW) using the Takakura Composting Method. During the 30-day composting period, nutrient content, including total nitrogen (TN), total phosphorus (TP), potassium (K), carbon to nitrogen (C/N) ratio, pH, and phytotoxicity as measured by germination index (GI), were evaluated. The compost quality index (CQI) was also used to evaluate the quality of the compost. The results showed that all VW, FW and MFW had pH values, TN, TP, K and C/N ratios that were within the acceptable range for mature and high-quality compost. The GI of VW and MFW were both above 80%, while FW’s GI was slightly phytotoxic at 79.3%. Based on the CQI score, MFW was found to be a very good compost variant, trailed by VW and FW. The results show that EM can accelerate the production of high-quality compost, which benefits conservation efforts.

Compostagem de resíduos vegetais frescos e sua aplicação no cultivo de alface

ABSTRACT A considerable part of fresh plant-based food has been discarded as waste, although it could be used to make organic compost for growing plants, retaining nutrient that would be discarded without any control in the environment. The aim of this study was to produce an organic compost using fresh vegetable food discarded from restaurants and mowed grass and to evaluate it for production of lettuce. The compost was produced and mixed with the commercial substrate Tropstrato HT Hortaliças® to occupy 0, 5, 10, 15, 20 or 25% of the volume of the mixture, which was used to grow Imperial and Imperial Roxa cultivars in the first experiment, and Camila and Red Star lettuce cultivars in the second one. The experiments were conducted under protected environment, organized in a 6x2 factorial scheme, following completely randomized design with three replicates. Chemical analyses of the substrate and compost and measurements of plant size and mass were carried out. The addition of compost caused an increase in all measurements of the plant traits, with the maximum estimated increase ranging from 1.7 to 9.0 times that estimated for the absence of compost in the plant growth substrate. Maximum estimated values for size and mass were observed with compost concentrations ranging from 20.1 to 26.7% of the mixture volume. The production of organic compost and its mixture with a commercial substrate proved to be an alternative for lettuce production, giving a better destination to the organic residues and promoting a reduction in the use of industrial inputs.

Experimental study of biogas production from water hyacinth

In the Littoral and East regions of Cameroon, the proliferation of the water hyacinth threatens the conservation of biodiversity. Indeed, its rapid multiplication asphyxiates fish and promotes malaria. Integrated pest management and many other methods have been used to eliminate this plant, but it persists, endangering the eco-systemic balance of marine environments. The efficient management of this plant remains a challenge. The aim of this study is to contribute to the implementation of a water hyacinth management protocol. The idea was to use this plant not only for natural fertilizer for soil improvement but also as energy production (biogas). The tests were carried out at the HIMA application farm in the Abong-Mbang area. Experiments were conducted using 60-Liters batch digesters. In all three sets of experiments, combinations of water hyacinth, cow dung and chicken droppings were used. For water hyacinth alone, an average production of 70 L of biogas was recorded. The best yield was obtained for the mixture of water hyacinth (5 kg), cow dung (1.5 kg) and chicken droppings (1 kg) at 1/4 dilution, i.e. 179 L/kg of substrate. The results obtained are encouraging and are being effectively used. This technology can therefore be applied in areas infested by Eichhornia crassipes for the production of energy, compost and control of water hyacinth proliferation.

Effects of different composting methods on antibiotic-resistant bacteria, antibiotic resistance genes, and microbial diversity in dairy cattle manures.

Composting is a common practice used for treating animal manures before they are used as organic fertilizers for crop production. Whether composting can effectively reduce microbial pathogens and antibiotic resistance genes remain poorly understood. In this study, we compared 3 different dairy manure composting methods-anaerobic fermentation (AF), static compost (SC), and organic fertilizer production (OFP)-for their effects on antibiotic-resistant bacteria, antibiotic resistance genes, and microbial community diversity in the treated manures. The 3 composting methods produced variable and distinct effects on antibiotic-resistant bacteria, zoonotic bacteria, and resistance genes, some of which were decreased and others of which showed no significant changes during composting. Particularly, SC and OFP reduced chloramphenicol resistance gene fexA and opportunistic pathogen Vibrio fluvialis, whereas AF significantly reduced tetracycline resistance gene tetB and opportunistic pathogens Enterococcus faecium and Escherichia fergusonii. The compositions of microbial communities varied significantly during the composting processes, and there were significant differences between the 3 composting methods. In all 3 composts, the dominant phyla were Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria. Interestingly, Firmicutes, Proteobacteria, and Bacteroidetes remained stable in the entire AF process, whereas they were dominated at the beginning, decreased at the early stage of composting, and rebounded at the later stage during SC and OFP. In general, SC and OFP produced a more profound effect than AF on microbial community diversities, pathogens, and dominant species. Additionally, Enterococcus aquimarinus was isolated from AF for the first time. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States function prediction analysis indicated that the genes related to membrane transport and amino acid metabolism were abundant in the 3 composts. The metabolism of amino acids, lipids, and carbohydrates increased as composting progressed. The biosynthesis of antibiotics was enhanced after fermentation in the 3 composting methods, and the increase in the SC was the most obvious. These results reveal dynamic changes in antibiotic-resistant bacteria, antibiotic resistance genes, microbial community composition, and function succession in different dairy manure composts and provide useful information for further optimization of composting practices.