Compost Characteristics Research Articles

Physico- Chemical characteristics of compost (Cotonou, Benin, West Africa)

This work was led the town of Cotonou in Benin and particularly on the vegetable garden site of Houéyiho. It involved the valorization of the waste of this site by proceeding the aerobic composting of the biodegradable fraction of municipal solid waste collected in the markets. This consists among other rotten fruits of various plant debris and garbage obtained by initial sorting. After three months of biological decomposition, 48,531.78 kg of biodegradable waste was composted with a yield of 40,443.33 kg of fresh compost or approximately 83.33% compost. The moisture content of the biodegradable fraction is 65%. The physico-chemical characteristics of compost produced are as follow: 12.7594 ± 0.1006 mg / kg of heavy metals, the C / N ratio is 13% and the rate of total phosphorus is 0.34% and 61.18 meq/100 g of Dry Weight exchangeable bases. The humus of our compost has a high capacity of cationic exchange (CCE) and fixed mineral nutrient ions such as K+ and Ca2+ and phosphate in order to make them available for plant growth and development and proving the poverty of the soil of this site and their increased need of organic amendment.Keywords: Cotonou; biodegradable waste; compost; physico- chemical characteristics; poor soil

Impact of laccase enzyme inducers on solid waste compost maturity and stability

The influence of inducers of laccase produced by Pleurotus ostreatus-P1 on the physicochemical properties of solid waste compost was investigated. In order to examine the degree of humification and time period for maturity and stability of compost, three different treatments (T: laccase; T1: laccase+CuSO4; and T2: laccase+CuSO4+CaCl2) were inoculated on solid waste in the initial stage of the composting process. During the composting process, the carbon nitrogen ratio (C/N), nitrate (), ammonium nitrogen (), cation exchange capacity (CEC), humic acid (HA) and fulvic acid (FA) humification rate (HR), Humification Index (HI), and degree of polymerization (DP) were assessed for the evaluation of compost maturity and stability, and it was found that T2 treatment C/N, CEC, and HI was greater, 46.8%, 37.2%, and 38.46%, respectively, than T at the end of the maturation phase. Optimum degree of maturity was also appraised by the Germination Index, 98.25% was attained by T2, whereas 88.65% and 71.23% by T1 and T, respectively. Significant Pearson correlation was also found between compost characteristics such as C/N, CEC, HA, FA, DP, HI, and HR. In addition, also obstinate the mineralization's of nitrogen under laboratory incubation, using soil amended by 50 and 100 kg-N/ha and examined an increasing trend in nitrogen mineralization with the application rate. Moreover, it was concluded that the laccase inducers increase the disintegration and humification process during solid waste composting.

CONTROL OF XANTHOMONAS CAMPESTRIS pv. VESICATORIA USING AGROINDUSTRIAL WASTE-BASED COMPOST

Here we review the suppressive capacity of 14 agroindustrial subproduct-based compost against the disease caused by Xanthomonas campestris pv. vesicatoria (Xcv) in tomato crops. The obtained results have shown that the in vitro compost’s suppressive effect on Xcv growth was mainly due to biotic factors, since sterilised compost samples were not effective. The most effective composts were 44TRI, 50, 51, 52 and 55, while the rest of them apparently did not affect the in vitro growth of the bacterium. When the same composts were applied in a tomato seedbed, the sample named 51 showed the most suppressive effect against the symptoms caused by the pathogen. Disease incidence reduction after this treatment reached 80%. In this case, a clear indirect relationship was detected between disease incidence and fresh weight losses of treated plants. Finally, the suppressive characteristics of an agroindustrial-based compost were improved after the inoculation with a biological control agent, a strain of Bacillus pumilus MSW231 known to be effective against Xcv. In this case, the isolation of the pathogen from infected plants was reduced up to 95% as compared to plants treated with another non-suppressive substrate. The present results indicate that the agroindustrial subproducts-based compost posseses an important suppressive effect towards the disease caused by Xcv, mainly due to biotic factors, and therefore it can be improved by the inoculation with biological control agents, worsened by sterilization and even modified by the inoculation with other biological control agents, so as to obtain an effective compost a la carte.

DESIGNER COMPOST: FACTS OR FANTASY? A CASE STUDY ON COMPOST RICH IN LIGNIN AND LOW IN PHOSPHORUS

Application of compost as a source of stabilized organic matter is one strategy for increasing the organic carbon content of arable land. To meet environmental standards on nutrient leaching, especially the total P content of the composts limits the application rate. A functional compost with high lignin content and low P concentration would be a valuable tool for maintaining soil fertility. We aimed to determine the effect of feedstock composition on P and lignin content in compost. The research is based on three farm compost experiments with three treatments each, and three compost experiments in nature conservation areas. Besides general characteristics, lignin and ergosterol content and total P and N concentrations were measured in the composts. A 12-week incubation experiment was set up to measure N mineralization and P release by the composts when applied to the soil. In general, compost characteristics varied due to differences in feedstock and composting process characteristics. The produced farm composts had higher organic matter contents than the other composts; by feedstock selection farm composts with a total P content lower than 3 g P/kg dry matter were produced. The lignin content for the organic part of the compost was relatively constant for different compost types. The incubation experiments indicated that the effect on P availability in soil was strongly related to changes in soil pH after compost addition. Our results indicate that total P concentration of the feedstock materials should always be assessed in combination with mass reduction of the feedstock mixture during the composting process.

THE EFFECT OF BIODEGRADATION/DEGRADATION OF DEGRADABLE PLASTIC MATERIAL ON COMPOST QUALITY

Abstract The objective of this study was to find out whether the quality of compost would change during the process of composting carrier bags claimed by manufacturers as compostable or biodegradable in terms of parameters stipulated in the standard ČSN 46 5735 Industrial composts. Eight samples were subjected to the composting process in laboratory conditions. The compost samples were analyzed in the accredited laboratory. All samples met parameters stipulated for Class II. Seven samples of the eight met parameters stipulated in the standard ČSN 46 5735 for Class I. The samples had no influence on compost characteristics: strength, content of water and salt, pH value, content of nutrients or proportion of organic substances; other components of the compost remained unchanged. Optical changes of the compost did not occur either.

Energy and pressure requirements for compression of swine solid fraction compost

The excessive amount of pig slurry spread on soil has contributed to nitrate water pollution both in surface and in ground waters, especially in areas classified as vulnerable zones to nitrate in accordance with European Regulation (91/676/CEE). Several techniques have been developed to manage livestock slurries as cheaply and conveniently as possible and to reduce potential risks of environmental pollution. Among these techniques, solid-liquid separation of slurry is a common practice in Italy. The liquid fraction can be used for irrigation and the solid fraction, after aerobic stabilization, produces an organic compost rich in humic substances. However, compost derived from swine solid fraction is a low density material (bulk density less than 500 kg􀀀m–3). This makes it costly to transport composted swine solid fraction from production sites to areas where it could be effectively utilized for value-added applications such as in soil fertilization. Densification is one possible way to enhance the storage and transportation of the compost. This study therefore investigates the effect of pressure (20- 110 MPa) and pressure application time (5-120 s) on the compaction characteristics of compost derived from swine solid fraction. Two different types of material have been used: composted swine solid fraction derived from mechanical separation and compost obtained by mixing the first material with wood chips. Results obtained showed that both the pressure applied and the pressure application time significantly affect the density of the compacted samples; while the specific compression energy is significantly affected only by the pressure. Best predictor equations were developed to predict compact density and the specific compression energy required by the densification process. The specific compression energy values based on the results from this study (6-32 kJ􀀀kg–1) were significantly lower than the specific energy required to manufacture pellets from biomass feedstock (typically 19-90 kJ􀀀kg–1).

Effect of composting on the Cd, Zn and Mn content and fractionation in feedstock mixtures with wood chips from a short-rotation coppice and bark

Micronutrient content and availability in composts may be affected by the addition of wood chips or tree bark as a bulking agent in the compost feedstock. In the first part of this study, micronutrient levels were assessed in bark and wood of poplar and willow clones in a short-rotation coppice. Large differences between species were observed in bark concentrations for Cd, Zn and Mn. In the second part of the study, we aimed to determine the effect of feedstock composition and composting on Cd, Zn and Mn concentrations and availability. By means of three composting experiments we examined the effect of (a) bark of different tree species, (b) the amount of bark, and (c) the use of bark versus wood chips. In general, compost characteristics such as pH, organic matter and nutrient content varied due to differences in feedstock mixture and composting process. During the composting process, the availability of Cd, Zn and Mn decreased, although the use of willow and poplar bark or wood chips resulted in elevated total Cd, Zn or Mn concentrations in the compost. Cd concentrations in some composts even exceeded legal criteria. Cd and Zn were mainly bound in the reducible fraction extracted with 0.5M NH2OH⋅HCl. A higher acid-extractable fraction for Mn than for Cd and Zn was found. Higher Cd concentrations in the compost due to the use of bark or wood chips did not result in higher risk of Cd leaching. The results of the pH-stat experiment with gradual acidification of composts illustrated that only a strong pH decline in the compost results in higher availability of Cd, Zn and Mn.

Pressure and specific energy requirements for densification of compost derived from swine solid fraction

Compost derived from swine solid fraction is a low density material (bulk density less than 500 kg m-3). This makes it costly to transport from production sites to areas where it could be effectively utilized for value-added applications such as in soil fertilization. Densification is one possible way to enhance the storage and transportation of the compost. This study therefore investigates the effect of pressure (20-110 MPa) and pressure application time (5-120 s) on the compaction characteristics of compost derived from swine solid fraction. Two different types of material have been used: composted swine solid fraction derived from mechanical separation and compost obtained by mixing the first material with wood chips. Results obtained showed that both the pressure applied and the pressure application time significantly affect the density of the compacted samples; while the specific compression energy is significantly affected only by the pressure. Best predictor equations were developed to predict compact density and the specific compression energy required by the densification process. The specific compression energy values based on the results from this study (6-32 kJ kg-1) were significantly lower than the specific energy required to manufacture pellets from biomass feedstock (typically 19-90 kJ kg-1).

Gas emissions as influenced by home composting system configuration

Home composting systems (HC) are known to facilitate municipal solid waste management, but little is known about their environmental impact including their greenhouse gas emissions (GGE). The present research focused on selecting HC configuration producing the least CH4 and N2O. Thus, 4 HC types were used to compost food and yard waste for 150 days and monitored for CO2, CH4 and N2O as of day 15: the wood and plastic bins (WB and PB), the mixed and unmixed ground pile (GPM and GP). Using the same waste recipe, all HC were filled at once (batch fed) to maximize gaseous emissions. Weekly as of day 15, CO2, N2O and CH4 emissions were measured during 2-h sessions using a closed chamber inserted into the compost surface. Monitored compost characteristics indicated little differences over time except for moisture content. From day 15 to 150, CH4 emissions were not measurable. Generation of N2O occurred between day 20 and 120 with PB producing the least because of top and bottom slots providing continuous convective aeration, as compared to the WB with slats over its full height and the naturally aerated mixed and unmixed ground piles. Total N2O emissions of 56 kg CO2-eq (tonne wet waste treated)−1 for PB, 75 for GP, 97 for WB and 99 for GPM represented average value for centralized composting facilities. Present and past scientific works suggest the need for more research to establish the combined effect of management and HC configuration on gaseous emissions, with close CH4 measurements from day 0 to 15.

Energy and pressure requirements for compression of swine solid fraction compost

The excessive amount of pig slurry spread on soil has contributed to nitrate water pollution both in surface and in ground waters, especially in areas classified as vulnerable zones to nitrate in accordance with European Regulation (91/676/CEE). Several techniques have been developed to manage livestock slurries as cheaply and conveniently as possible and to reduce potential risks of environmental pollution. Among these techniques, solid-liquid separation of slurry is a common practice in Italy. The liquid fraction can be used for irrigation and the solid fraction, after aerobic stabilization, produces an organic compost rich in humic substances. However, compost derived from swine solid fraction is a low density material (bulk density less than 500 kg􀀀m–3). This makes it costly to transport composted swine solid fraction from production sites to areas where it could be effectively utilized for value-added applications such as in soil fertilization. Densification is one possible way to enhance the storage and transportation of the compost. This study therefore investigates the effect of pressure (20- 110 MPa) and pressure application time (5-120 s) on the compaction characteristics of compost derived from swine solid fraction. Two different types of material have been used: composted swine solid fraction derived from mechanical separation and compost obtained by mixing the first material with wood chips. Results obtained showed that both the pressure applied and the pressure application time significantly affect the density of the compacted samples; while the specific compression energy is significantly affected only by the pressure. Best predictor equations were developed to predict compact density and the specific compression energy required by the densification process. The specific compression energy values based on the results from this study (6-32 kJ􀀀kg–1) were significantly lower than the specific energy required to manufacture pellets from biomass feedstock (typically 19-90 kJ􀀀kg–1).

Recycling of anaerobic digestates by composting: effect of the bulking agent used

Digestate, the by-product of the anaerobic digestion, can present characteristics which would limit its recycling by direct use in agricultural soils. Composting can be a feasible treatment to stabilise digestate and thus, to improve its properties for using as a soil conditioner or substrate. The aim of this work was to study the viability of composting for the recycling of digestates after solid–liquid separation and the effect of the bulking agent used in the characteristics of the end-products obtained. For this, five piles were elaborated by mixing the solid fraction of a pig slurry digestate (SD) with different bulking agents (wheat straw (WS), vine shoot prunings (VP), exhausted grape marc (EGM) and pepper plant prunings (PP)). Also, one of these piles was watered with the liquid fraction of the pig slurry digestate (LD). Throughout the composting process, the temperature of the mixtures was monitored and physico-chemical, chemical, physical properties and maturity degree were determined. Also, factorial analysis (FA) was used for interpreting the data set of compost characteristics. The composts obtained showed a suitable degree of stability and maturity and suitable physical properties for their potential use as growing media. Also, the type of bulking agent strongly influenced the development of composting and the final properties of the composts, showing the mixtures with WS and VP the most suitable characteristics.

Effect of C/N ratio on the in-vessel composting under air pressure of organic fraction of municipal solid waste in Morocco

The goal of this research was to investigate the effect of the C/N ratio on the in-vessel composting, under air pressure, of organic fraction of municipal solid waste in Morocco. Firstly, an in-vessel bioreactor was designed and used to evaluate the appropriate initial pressure for the composting process. Secondly, five bioreactors were run with C/N ratios of 26 (control; no C supplement), 32.2, 38.4, 44.6, and 50.8. Parameters monitored included internal air pressure, C/N ratio, temperature, volatile solids reduction, and maturity of the obtained composts. The relative microbial activity was observed indirectly using volatile solids removal and the relative heat generation data. The experimental results showed that organic waste could be composted within 10 days and the operating initial parameters that converted the most volatile solids and carbons in the feedstock were as follows: 0.6 × 105 Pa for the initial air pressure and 26 for the C/N ratio. Maturity tests, in optimal conditions, showed that the final compost has characteristics of stable compost and can be used as a soil conditioner. In addition, compost obtained from the experiment that considered a C/N ratio of 32.2 showed good maturity levels and may also be used for agricultural applications.

Impact of climate and bulking materials on characteristics of compost from ecological toilets

Urine-diversion dehydration toilets (UDDT) are common throughout the developing world, and the toilet product is widely used as compost. There is no comprehensive research to date that characterizes the compost to determine its quality, extent of pathogen inactivation, and the effects of climate and bulking materials on the compost. Compost was collected from 45 UDDT in Bolivia and analyzed for physical, chemical, and biological parameters. Eighty percent and 56% of samples did not meet acceptable compost guidelines for moisture content and pH, respectively, indicating desiccation was the dominant process in UDDT. Bulking materials significantly impacted compost characteristics in terms of pH, carbon, carbon-to-nitrogen ratio, and carbon stability (P < 0.05). Composts with ash exhibited, on average, low carbon concentrations (4.9%) and high pH values (9.7), which can be harmful to plants and composting microorganisms. Composts with sawdust exhibited, on average, high carbon concentrations (40.0%) and carbon-to-nitrogen ratios (31.0). Climate had no significant impact on chemical characteristics, however composts from humid regions had significantly higher moisture contents (34.4%) than those from arid climates (24.8%) (P < 0.05). Viable Ascaris lumbricoides ova were identified in 31% of samples, including samples with high pH, low moisture contents, and long storage times.

A complete mass balance of a complex combined anaerobic/aerobic municipal source-separated waste treatment plant

In this study a combined anaerobic/aerobic full-scale treatment plant designed for the treatment of the source-separated organic fraction of municipal solid waste (OFMSW) was monitored over a period of one year. During this period, full information was collected about the waste input material, the biogas production, the main rejects and the compost characteristics. The plant includes mechanical pre-treatment, dry thermophilic anaerobic digestion, tunnel composting system and a curing phase to produce compost. To perform the monitoring of the entire plant and the individual steps, traditional chemical methods were used but they present important limitations in determining the critical points and the efficiency of the stabilization of the organic matter. Respiration indices (dynamic and cumulative) allowed for the quantitative calculation of the efficiency of each treatment unit. The mass balance was calculated and expressed in terms of Mgy−1 of wet (total) matter, carbon, nitrogen and phosphorus. Results show that during the pre-treatment step about 32% of the initial wet matter is rejected without any treatment. This also reduces the biodegradability of the organic matter that continues to the treatment process. About 50% of the initial nitrogen and 86.4% of the initial phosphorus are found in the final compost. The final compost also achieves a high level of stabilization with a dynamic respiration index of 0.3±0.1g O2 per kg of total solids per hour, which implies a reduction of 93% from that of the raw OFMSW, without considering the losses of biodegradable organic matter in the refuse (32% of the total input). The anaerobic digestion process is the main contributor to this stabilization.

Evaluation of Fluted Pumpkin (Telfairia occidentalis, Hook f.) Waste as Nutrient Amendment in Compost for its Effective Management and Crop Production

The study investigated the Telfairia occidentalis waste (leaves and stalk) potential in supplementing the naturally low nutrients in compost. Experimental study design was conducted inside windrows to compare different recipes for aerobic composting of the waste. Total of four windrow chambers (labeled as: AA, BB, CC, TO) were used. Inside each chamber, compost recipes were varied viz: AA contained mixture of Telfairia occidentalis waste, Cow Intestinal Waste (CIW) and other organic waste from Mixed Municipal Waste (MMW); BB contained Telfairia occidentalis waste and CIW; CC contained CIW and MMW; and, TO contained Telfairia occidentalis waste alone. The ratio of 3:1 was maintained for either Telfairia occidentalis waste or MMW and cow waste respectively. The materials were allowed to decompose for a period of 12 weeks. At maturity composts samples were analyzed for their nutrient and heavy metal compositions. BB appeared to be the best recipe for Telfairia occidentalis waste management through composting. It gave the highest values for the following nutrients: C (37.350±0.212 %), N (3.205±0.007 %), P (1.310± 0.028 %), Mg (0.500±0.057 %), and Ca (0.730±0.028 %) that are of good compost characteristics. The levels of nutrients and heavy metals were within the ranges of national and international standards. Hence, the management of Telfairia occidentalis waste through composting serves dual purposes of recovering nutrients locked-up in the stalk and leaves for plant growth and environmental sanitation. Keywords - Composting, Environmental sanitation, Fluted pumpkin, Plant growth, Waste management

Ham Kompost ve Ekstraksiyon İşlemine Tabi Tutulmuş Kompost Numunelerinin Karakterizasyonları ve Bitkiye Yarayışlılıkları Açısından Karşılaştırılması

In this study, the effect o f extraction process on the compost structure and its plant growing characteristic was investigated. Compost samples (raw compost sample taken from compost production facility and compost samples extracted with Na2EDTA and Na2S2O 5 mixture or molasses hydrolyzate) have been characterized and these samples structures were examinated by XRD, SEM and IR analysis. The experiments o f compliance with the plant (phytotoxicity experiments) have been conducted to determine the plant growing characteristic o f the compost samples. When the results obtained from experimental studies were evaluated, it was determined that the best plant growing were achieved using 0.01 M Na2EDTA-0.1 M Na2S2O 5 solution. The plant growing efficiency value was 97% for 25% compost:soil mixture. When the results obtained from studies were evaluated, it was determined that extraction processes caused both remarkable changes in compost characteristics and compliance with plant.

Compost type effects on nitrogen leaching from Inceptisol, Ultisol, and Andisol in a column experiment

To more efficiently utilize composts as N sources while minimizing the environmental impact, it is necessary to understand the effects of compost type on N mobility in compost-amended soil with different characteristics. The objectives of this study are to investigate the effects of livestock manure composts on N leaching from soils and to identify the principal physicochemical variables of the composts that affect N leaching. A combination leaching-incubation experiment using seven livestock manure composts and three soils (Inceptisol, Ultisol, and Andisol) with different characteristics was conducted for 19 weeks. Leachates were collected periodically and analyzed for various forms of N (NH 4 + , NO 3 − , organic N, and total N). The effects of compost type on N leaching were assessed by analysis of variance and correlation between N leaching amounts and compost variables (pH, total C, total N, C/N, and various forms of extractable N). Initial flush of N leaching at the first leaching event conducted after 1-week incubation was observed probably due to mineralization of readily decomposable N pool; the amount of N leached at 1-week incubation accounted for more than 50% of cumulative amount of N leached through 19-week incubation. Among the various compost variables tested, only total N concentration of compost was significantly (P < 0.05) correlated with total N and mineral N (NH 4 + + NO 3 − ) leached across all three soils, indicating that total N concentration of composts is the common factor affecting N leaching from the compost-amended soils. Comparing amongst the three soils, the cumulative amount of total N leached increased in the order of Andisol (34.5 to 103.4 mg N) > Ultisol (33.9 to 64.7 mg N) > Inceptisol (12.8 to 31.7 mg N) being affected by soil N availability. The significant effects of compost and soil types suggested that not only soils but also composts characteristics needs to be considered when establishing the compost application guidelines. Particularly when compost characteristics are considered, total N rather than the mineral N concentration of composts can be used to predict the N leaching potential in composts-amended soils.

Catalytic steam gasification of biomass in fluidized bed at low temperature: Conversion from livestock manure compost to hydrogen-rich syngas

Abstract Utilizing large amounts of animal waste as a source of renewable energy has the potential to reduce its disposal problems and associated pollution issues. Gasification characteristics of the manure compost make it possible for low temperature gasification. In this paper, an energy efficient approach to hydrogen-rich syngas from manure compost is represented at relatively low temperature, around 600 °C, in a continuous-feeding fluidized bed reactor. The effects of catalyst performance, reactor temperature, steam, and reaction type on gas yield, gas composition, and carbon conversion efficiency are discussed. The Ni–Al2O3 catalyst simultaneously promotes tar cracking and steam reforming. Higher temperature contributes to higher gas yield and carbon conversion. The steam introduction increases hydrogen yield, by steam reforming and water–gas shift reaction. Two-stage gasification is also tried, showing the advantage of better catalyst utilization and enhancing the catalytic reactions to some extent.

Sewage sludge composting: Influence of initial mixtures on organic matter evolution and N availability in the final composts

The influence of bulking agents on organic matter (OM) stability and nitrogen (N) availability in sewage sludge composts was investigated. The same sludge was composted on an industrial plant with different mixtures of bulking agents. The composting process included an active phase and a curing phase, both lasting 6 weeks, separated by the screening of composts. The OM evolution was characterised by carbon (C) and N mass balances in biochemical fractions. The OM stability and N potential availability of final composts were measured during soil incubations. During composting, the C and N losses reached more than 62% of the initial C and more than 45% of the initial N, respectively, due to C mineralisation or N volatilisation and screening. The bulking materials mostly influenced OM evolution during the active phase. They contributed to the mitigation of N losses during the active phase where N immobilisation through active microbial activity was favoured by bulking agents increasing the C:N ratio of the initial mixtures. However, the influence of bulking agents on OM evolution was removed by the screening; this induced the homogenisation of compost characteristics and led to the production of sludge composts with similar organic matter characteristics, C degradability and N availability.

In-vessel treatment of urban primary sludge by aerobic composting

The aim of this work is the study of recycling urban primary sludge by in-vessel aerobic composting way. Two series of composting trials were carried out in an automated accelerated bioreactor in mixture with agricultural wastes: sugar beet leaves (C1); straw, sheep manure and sugar beet leaves (C2). Treatments were monitored with regard to physicochemical characteristics, heavy metal amounts and microbiological parameters of the final compost product.The general pattern of the temperature curve was typical for composts of organic waste. The different physicochemical characteristics of the final composts after a retention time in the bioreactor of 30 and 23days, respectively for C1 and C2 were: pH: 7.3–7.2; C/N: 10.2–12; organic matter: 49.7–58.3%; NH4+/NO3-: 0.24–0.2.Final compost showed low amounts of heavy metals, relatively high contents of nutrients and significant reduction of pathogens, suggesting the agricultural purposes of urban primary sludge.