Compost Mass Research Articles

Innovation for recycling of organic matter through composter with automatic and sustainable temperature recording accessed via Bluetooth/mobile app.

Compost reactors, commonly used in experiments, industrial assays, and home residue treatment systems, have the potential to facilitate composting. Challenges persist in the realm of small-scale composting, encompassing facets such as temperature monitoring, homogenization of the compost mass, management of moisture with the control of leachate generation, and integration with a renewable energy source. This study assesses a pioneering composter prototype endowed with essential features to ensure a pragmatic and secure composting process. This includes the facilitation of remote access to temperature data via Bluetooth and a mobile application. Across successive trials, the scrutinized composter prototype consistently yielded reproducible outcomes, exhibiting a coefficient of variation below 25% for the majority of appraised parameters. In comparison to a conventional reactor, the decomposing residue mixture within the examined prototype manifested elevated temperatures (p < 0.05). Moreover, the tested prototype demonstrated C/N ratio lower than 20/1 within 45days, a higher final nitrogen concentration, and enhanced germination of seeds that served as phytotoxicity bioindicators. Notably, the prototype needed 46.6% less space, offering improved leachate control, three times faster turning time, temperature monitoring, and reduced fly attraction.

Biochar-Poultry Manure Compost Alters Temperature and Nitrogen Dynamics during Composting and Improves Potato Growth Following Field Application

Composting is an aerobic process that transforms organic wastes into valuable agricultural product, but the composting process frequently results in losses of nitrogen (N) through NH3 volatilization. We evaluated the potential for high-temperature, wood-based biochar to reduce N loss when included as a compost feedstock. Biochar was composted with wood shavings and poultry manure (4:1 v/v) at rates of 0, 20 and 40% (v/v) in replicated, actively aerated 1.43 m3 in-vessel compost piles. Biochar addition caused more rapid temperature increase and truncated thermophilic phase. N loss from the entire compost mass was reduced with 40% and 20% biochar addition compared to the control (29.9, 32.3, and 35.6% N loss, respectively; P value = 0.027). However, assuming no N was lost from the added biochar, difference in N loss was less significant (P value = 0.100). With 40% biochar addition, finished compost had greater NO3 --N concentration, lower electrical conductivity, greater carbon to nitrogen ratio, and greater total carbon content. Compost products were amended to soil at rates of 7 or 15 Mg C ha−1 in potato production. Relative to an unamended control, the high application rates tended to decrease bulk density and increase total N in soil, but no differences were detected between the compost or composted biochar treatments. Tuber weights were increased 40% with application of composted biochar (biochar 40% v/v). Biochar is a promising bulking agent for composting which may reduce N loss and increase nitrification. Future studies should examine how specific biochar products affect the compost process, nutrient retention, and crop production.

Kućna predobrada biootpada primjenom Bokashi metode

Approximately one-third of municipal solid waste is biodegradable waste, necessitating its urgent processing into compost or biogas. Indoor composting of biowaste has recently received increased attention due to its economic, environmental, and social benefits, offering a significant contribution to sustainable waste management and circular economy. Instead of disposing of biowaste in landfills, compost is produced as a useful organic soil improver, fertiliser or bio-based product. This study analyses the physicochemical parameters of biowaste and the obtained pre-compost during the Bokashi treatment, considering the effects of different inoculants, occasional mixing of biowaste, and exposure to air. The pretreatment of biowaste was compared based on pH, electrical conductivity, temperature and height of the compost mass, moisture, dry matter, volatile matter, carbon and nitrogen content, and C/N ratio. Collected leakages were analysed for volume, pH, electrical conductivity, and turbidity. In addition, the obtained pre-composts underwent further maturation in two soil types, and the same physicochemical parameters were monitored. Finally, FTIR spectroscopy was employed to analyse the initial biowaste, final pre-compost masses, and the collected leakages. There is no significant difference between the pre-composts and also between the leakages. The results indicate that Bokashi treatment of biowaste with &amp;lt;i&amp;gt;Inoculant 1&amp;lt;/i&amp;gt; efficiently yielded a higher carbon and nitrogen content in the final pre-compost, and produced a lower volume of compost leakage. This paper highlights the Bokashi method’s efficiency in facilitating indoor biowaste treatment.

Determining the extraction conditions and phytotoxicity threshold for compost maturity evaluation using the seed germination index method

The phytotoxicity of the compost aqueous extracts determines the maturity. To improve the accuracy of compost maturity evaluation using the seed germination index (GI) method, different extraction methods (different moisture content and extraction ratio) were designed to obtain samples with various phytotoxic level. This study analyzed the effects of different extraction condition of compost samples on GI, and established the relationship between phytotoxicity and GI. The results showed that the moisture content and extraction ratio of the compost significantly affected the GI. The extraction ratio for the compost with 60–70 % moisture content was 1:10 (ratio of compost mass to extract volume). However, commercial compost, which must have a moisture content of 30–45 %, had an extraction ratio of 1:30 (w:v). More importantly, compost extraction based on dry weight, with a moisture content of 10–15 %, more effectively reflected the phytotoxicity variations during composting. In such cases, the extraction ratio should be at least 1:30 (w:v) but not exceed 1:50 (w:v). The relationship between phytotoxicity and GI showed that dissolved organic carbon and dissolved nitrogen were the most important factors influencing GI, followed by NH4+, electrical conductivity, K, volatile fatty acids, Zn, and Cu. For composts with a GI greater than 70 %, the dissolved organic carbon, dissolved nitrogen, and NH4+ concentrations were below 257, 164, and 73 mg/L, respectively. These findings provide an optimized standard method for compost maturity evaluation using GI and a concentration threshold of key phytotoxicity is proposed to achieve accurate control of compost maturity.

The various effect of cow manure compost on the degradation of imazethapyr in different soil types

Adding compost to soil is an effective strategy to promote the degradation of organic pollutants and reduce ecological risks. However, the effect of compost on the degradation of imazethapyr (IMET) in different soil types is not clear. To address this issue, a pot experiment was conducted, and high-throughput sequencing and mass spectrometry technology were used to identify the influence of cow manure compost on the degradation efficiency of IMET in black soil and saline-alkali soil and the role of key microorganisms. The results showed that adding compost to black soil increased the degradation rate of IMET by 12.58% and shortened the half-life by 53.37%, while in saline-alkali soil, the degradation rate of IMET decreased by 6.99% with no significant change in the half-life. High-throughput sequencing results showed that adding cow manure compost (mass ratio of 4%) significantly increased the abundance of bacterial families capable of degrading organic pollutants in black soil, but had an inhibitory effect on this bacterial community in saline-alkali soil. Redundancy analysis (RDA) results showed that total organic carbon (TOC), alkali-hydrolyzable nitrogen (AN), ammonia nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) were the main factors driving microbial community variation. Mass spectrometry analysis indicated that IMET generated three metabolites during the degradation process. Sphingomonadaceae and Vicinamibacteraceae could accelerate the breaking of side-chain alkyl groups, while Chitinophagaceae could cause the rearrangement of the imidazole ring structure, gradually metabolizing IMET into small organic molecules. The application of appropriate cow manure compost can promote the development of IMET-degrading bacteria by adjusting the organic carbon and dissolved nitrogen content in black soil. In the future, the quantitative effects of organic fertilizer application on the IMET degradation process in different soil types should be further analyzed, and microbial isolation and purification should be used to enhance the ability of microorganisms to degrade herbicides.

Heavy Metals in Fly Ash as a Factor Limiting Its Use in Fertilizing Composts

Composting enables the recycling of significant amounts of biodegradable waste, while ensuring its disposal. The addition of fly ash increases the concentration of fertilizing substances in the compost. Compost is a source of many nutrients for plants. The addition of fly ash might also cause a slower release of these nutrients into an aqueous solution, meeting the fertilization needs of plants over a longer period of time. Tests were carried out using sewage sludge (WWTP Piaseczno, 163,500 P.E.), straw as a structure-forming material and fly ash (WWTP Krakow, 780,000 P.E.). The compost obtained in the research was analyzed in terms of environmental conditions specified in legal regulations. The most favorable compost mass density (520 kg/L) and the amount of air supplied to the process (5.0 L/(h∙kg d.m.)) were determined. The addition of fly ash to the compost mass did not significantly affect the temperature distribution obtained in the process. The increase in fly ash content increased the pH of the compost mass and was associated with higher nitrogen losses. It was found that the factor which may limit the possibility of using fly ash as a compost substrate is the presence of higher concentrations of heavy metals, especially chromium. It was determined that the maximum addition of fly ash to the compost mass was 154 kg d.m.ash/(ton d.m.straw+sludge).

Decomposition and nutrient release patterns of municipal solid waste compost in two agro-ecological zones of Uganda

BackgroundDeteriorating soil fertility is a major constraint to agricultural production and food security among smallholder farmers in Uganda and throughout sub-Saharan Africa, where the majority of the population relies on subsistence farming for its livelihoods.Unfortunately, inorganic fertiliser used as a significant soil nutrient replenishment is unsustainable, causing adverse environmental effects, including soil acidification and pollution of water bodies. Therefore, finding alternative, more sustainable, low-cost nutrient management systems is vital. This study assessed the decomposition and nutrient release patterns of municipal solid waste compost (MSWC) in a 36 weeks litter bag experiment under field conditions in two agro-ecological zones (AEZs) of Uganda.ResultsWe found a higher rate of decomposition in the South-western Grass Farmlands (SGF) agro-ecological zone (0.041 week−1, with 20% of initial compost mass remaining after 36 weeks of decay) compared to Southern and Eastern Lake Kyoga Basin (SEKB) (0.043 week−1, 32% of initial litter mass remaining). The half-life values were 16 and 17 weeks for SGF and SEKB AEZs, respectively. The nutrient release rates differed between the two study sites. The macronutrient release pattern in both sites followed the order K > P > N. The secondary macronutrients release followed the order Ca > Mg in the SGF, while in SEKB, the order was reversed. The micronutrients followed the order Cu > Mn > Fe > Zn and Cu > Mn > Zn > Fe in SGF and SEKB AEZs, respectively. The MSWC mass loss during decomposition was negatively correlated with rainfall in both AEZs and with temperature in SGF AEZ, while it was positively correlated with temperature in SEKB AEZ. However, the relationship with nutrient release rates was inconsistent in both AEZs.ConclusionsOur results showed consistent release of nutrients in all AEZs throughout the study period, which coincides with the two cropping seasons in Uganda, suggesting that smallholder farmers can use MSWC as a soil amendment to address soil fertility decline and improve crop productivity. However, because most nutrients were released almost right away in both AEZs, planting should be done at the beginning of high rainfall months when soil moisture is high to synchronise nutrient release from MSWC with crop demand and maximise nutrient uptake by crops while minimising losses to the environment. Furthermore, the inconsistent relationships between the climatic variables and nutrient release suggest that other factors, such as site-specific microbial composition, influenced MSWC nutrient release. Therefore, long-term research is needed to examine other factors affecting nutrient release in these AEZs.

Effects of Initial C/N Ratio on Maturity and Stability of Compost Produced from Two-Phase Olive Mill Pomace, Poultry and Dairy Manure and Straw

Composting of two-phase olive mill pomace, poultry and dairy manure, and straw was conducted at five initial carbon/nitrogen (C/N) ratios (from 20.03 to 39.99) using 15 100-liter reactors. Compost temperature was controlled based on Rutgers aeration strategies. Composting trials lasted 19.35 days. A first-order rate equation was used to obtain the decomposition rate and compost mass ratio (the degree of advancement of the composting process). The compost stability index was calculated considering the decomposition rate and the rate of oxygen uptake per unit of dry matter loss based on biochemical oxygen demand. The nonlinear relationship between the compost stability index and the initial C/N ratio showed that a minimum value of 0.011 kg O2 day−1 kgc −1 existed at the initial C/N ratio of 28.92. The lower compost stability index indicated relatively more stable compost. The relationship between the final ratio and the initial C/N ratios indicated that the lowest final ratio of 0.26 occurred at the initial C/N ratio of 29.66. The germination index as a function of the initial C/N ratio yielded a strong negative linear relationship with R 2 of 0.95. Compost mixes with the high initial C/N ratio resulted in relatively lower germination indexes which are phytotoxic to plant growth. This study showed how the initial C/N ratio is important for compost stability and maturity.

Effect of the compost mixer machine on the quality of compost made from shredded oil palm fronds (OPF)

In general, the composting process made from oil palm fronds (OPF) is to reduce their size, mixing, and fermentation. One of the essential factors composting process is a mixed uniform between shredded OPF with other raw materials. In this paper, we discuss the quality of compost, which is stirred using a compost mixer machine (drum rotary double helix type). Composting methods chosen are natural inoculum and bokashi inoculum. Rotational speed of the mixer is applied at the levels of 100 rpm, 300 rpm, and 500 rpm. Parameters such as compost mass and temperature are recorded every five days for 60 days of composting duration. The N, P, K content, and C/N ratio were analyzed for 30 days and 60 days of composting duration. A total of 5 kg of mixed raw material was composted. Maximum temperatures recorded during the composting process of natural inoculum and bokashi methods were 35°C, 40°C, respectively. Mass loss of the two composting methods is 75%. A composting method, rotation speed, and composting duration do not significantly affect to achieve the Indonesian National Standard (SNI) quality of composting. Therefore, the use of various types of composting methods, low rotational speed compost mixer machine, and short composting duration can be applied to making compost using this machine.

Результати випробувань перемішувача компосту VK-3000 під час прискореного біотермічного компостування гною

The purpose of research: a comprehensive assessment of the compost mixer during operation. Research methods: the establishment of design features of the compost mixer was performed by the survey method provided for research sample, study of the quality of the technological process, operational-technological, energy and economic indicators, safety and ergonomics indicators were carried out by standardized methods according to DSTU 7435, DSTU 8424, DSTU 4397, DST 4748, CD 46.16.02.03, SOU 74.3-37-133. Research results: research of the product was carried out under us mixing of compost in piles. The research results show that the compost mixer satisfactorily performs the specified technological process. Mixing of the compost mass is carried out at a speed of 0.5 km / h. This loosens the burt, which is necessary to regulate the temperature and humidity of the burt, remove CO2 and saturate the mass with oxygen, which is necessary to improve the process of aerobic fermentation of the material laid for composting. The capacity of the compost mixer for the main time was 134 tons per hour and 113 tons per hour of variable time (taking into account the time for moving). No additional maintenance personnel are required to operate the unit, the compost mixer is operated by a machine operator. Labor costs are equal to 0.01 man-hours / ton. Direct operating costs are UAH 2.04 / t and an annual load of 760 hours. (3.0-3.5 years per day). Conclusions: During the technological process, the compost mixer provides uniform mixing of organic waste and the formation of a burr for its further fermentation. Maintaining the required temperature and humidity in the burr allows you to maintain the quality of compost and prevents the loss of its value. Compared to other trailed and self-propelled machines, the VK-3000 compost mixer has a performance that is sufficient for medium-sized enterprises. Direct operating costs are UAH 2.04 / t at a mixer price of UAH 900,000 The obtained high-quality biologically active fertilizers, thanks to the use of a compost mixer, provide an increase in crop yields by increasing soil fertility.

Production of Arugula Under Doses of Bokashi Fermented Compound

Fermented composts are made from animal, plant and or/mineral materials. The fermentation process can be accomplished through the action of microorganisms collected from soils, plant litter and/or baker&amp;rsquo;s yeast. This study aimed to evaluate arugula (Eruca sativa) yields with application of different doses of bokashi-type fermented compost. The experimental design consisted of randomized blocks with five treatments (0, 100, 200, 300, 400 g m-2) and four replications. Fermentation of the compost occurred in ten days, and in this period the compost mass was turned up twice a day during the first three days and daily during the seven next days. The fertilizer was incorporated three days before planting into a 0-5 cm deep layer. The methods used for data analysis were ANOVA and regression analysis at 5% probability level. The variables examined were: number of leaves, plant height, dry and fresh weight of roots and shoots. The use of bokashi at the rate of 300 g m-2 resulted in better agronomic performance, demonstrating to be a viable alternative for the production of arugula under local edaphoclimatic conditions.

English

Soil fertility transience and weed management are often among decried impediments undermining agricultural productivity in many tropical countries. A study aiming at transforming baffling problems of abundant weed biomasses especially that of Panicum maximum (T1), Tryps-acum laxum (T2) and Pueraria javanica (T3), often cause of crop yield loss into advantage to enhance soil fertility, increase crop productivity as well as help tackle weed issue was initiated in the region of Kisangani. To do this, a 90-day composting experiment involving a mono factorial randomized complete block design including three replications and three treatments of above mentioned weed biomasses was conducted from 23rd March to 23rdJune 2013. The results of analysis of variance showed significant differences among treatments for pH H2O (p&le;0.013) and potassium content (p&le;0.001). The three composts demonstrated high nutrient content level in total organic carbon, nitrogen and potassium able to restore soil fertility. Moreover, the study revealed that the pH values of all the composts were closer to neutral on average and can be used to fix the recurrent issue of soil acidity in the region. Finally, the results showed that the species were able to produce sufficient compost mass with 41.5, 36.3 and 30.9% of initial mass loss respectively for T1, T2 andT3 in a relatively short time. Key words: Soil fertility transience, compost, weed management, agricultural productivity, DR Congo. &nbsp

Improvement of humification and mechanism of nitrogen transformation during pig manure composting with Black Tourmaline

This study aimed to reveal the role of Black Tourmaline (TM) in the humification enhancement and the mechanism of nitrogen transformation during pig manure composting. Results showed that adding TM promoted the maturity and improved the humification degree by 20.13–33.77%. And TM was beneficial for the transformation from NH4+-N to amino organic nitrogen to fix more nitrogen in compost mass. Then NH3 and N2O volatilization were decreased by 22.88–34.76% and 69.79–87.47% by comparison with the control, and the minimum value in nitrogen loss (26.78%) was observed in the 10% TM blended treatment. Furthermore, through RDA analysis, the protease an upmost contributor to nitrogen transformation. Meanwhile, total organic carbon was dominant factor affected enzymatic activities. Therefore, 10% TM was suggested to reduce nitrogen loss and increase humification in this research. Deeply related research in gene and specific addition amounts of TM will be investigated later.

Degradations of tannin and saponin and changes in nutrition during co-composting of shell and seed cake of Camellia oleifera Abel

The degradation processes of tannin and saponin were studied during co-composting of the shell and seed cake of Camellia oleifera Abel. Four treatments were designed, with the dry weight of the seed cake accounting for 30% (A1), 25% (A2), 20% (A3), and 10% (A4) of the shell weight. During the composting, the duration and the highest temperature of the thermophilic phase were positively correlated with the addition proportion of seed cake. The degradation rates of tannin and saponin were positively correlated with the addition proportion of seed cake, but the C/N ratio and final tannin content were negatively correlated with it. The saponin content ultimately contributed to approximately 2% of the final compost mass. The final content of saponin and tannin decreased by 68.9 to75.2% and 34.6 to 59.5%. The organic matter and total nutrient content (N, P2O5, and K2O) increased with the increasing proportion of seed cake. An addition proportion of 30% of Camellia oleifera seed cake is recommended to produce homogenous compost. Overall, the addition of the seed cake promoted the maturity, fertilizer quality, and safety of the co-compost product.

Policy measures for sustainable sunflower cropping in EU-MED marginal lands amended by biochar: case study in Tuscany, Italy

The aim of this study is to evaluate economic support measures based on current EU policies affecting the profitability of large-scale deployment of biochar for sunflower cultivation in dry marginal lands in Italy, paving the way to large scale carbon sequestration in the EU Mediterranean region. Two cases were considered: i) straight biochar use and ii) biochar in combination with compost (COMBI: 20% biochar and 80% compost mass fraction), at application rates of 5 and 10 Mg ha−1 respectively. Based on realistic estimations of achievable crop-yield performances by biochar and COMBI addition to dry soils, the effect of current policies on the economic viability of biochar deployment and farmers’ income has been investigated. Using a cost-model we identified the required levels of support, in the form of (i) area subsidies for crop cultivation, (ii) tradable carbon certificates (credits), and (iii) REDII-compliant biofuel support for Aviation and Maritime, so to make biochar and sunflower cultivation in EU MED dry marginal lands competitive for sustainable crop-based biofuels. Results show that, by employing existing policy instruments, sufficient income can be generated for famers to recover marginal land, sequester large amount of carbon by BECCS at costs (∼82 € Mg−1 of CO2) falling at or below the typical range of CCS measures, as well as offer additional environmental and socio-economic positive benefits. The combination of currently operational economic mechanisms from the Common Agricultural Policy, the Climate Policy, and the Renewable Energy Directive II can: i) maintain domestic farming activities, ii) support the implementation of biochar projects at local level, iii) contribute to achieve EU and national biofuel targets without generating ILUC impacts and iv) achieve unprecedent potential for carbon sequestration. However, prior to large-scale deployment, targeted on-site R&D actions aimed at validating biochar effects under local conditions (soil, climate, crops) are recommended, together with training and capacity building activities for local farmers.

Composition of a Microbial Community at Different Stages of Composting and the Prospects for Compost Production from Municipal Organic Waste (Review)

This paper summarizes the current understanding of changes in the composition of the microbial community within compost in relation to the temperature at each stage of the process and explores the role of microbial associations in the biodegradation and detoxification of organic waste components. Attention is paid to the process of creating a balance between the active aerobic and anaerobic microorganisms in the compost mass, which allows nitrogen to be preserved in the finished compost and the cost of aeration to be reduced. It has been shown that the addition of natural minerals, in particular, zeolite, has a positive effect on the composting process and improves the quality of the compost, ensures the content of silicon in a bioavailable form in the compost, prevents ammonia emissions, and reduces the concentration of heavy metals. Particular attention is paid to the prospect of composting compacted anaerobically treated sewage sludge with the addition of an organic fraction of municipal solid waste (MSW) and lignocellulosic waste.

Changes in mineral forms of nitrogen and sulfur and enzymatic activities during composting of lignocellulosic waste and chicken feathers

The aim of this study was to show the dynamics of changes in the activity of enzymes responsible for C, N, and S metabolism, i.e., cellulase, protease, urease, and arylsulfatase in two lignocellulosic composts as well as changes in the concentration of mineral forms important in plant nutrition (N-NH4+, N-NO3−, S-SO42−). Most of the enzyme activity was higher during 10 weeks of composting in compost I, containing higher amounts of easily available organic matter than in compost II. Enzymatic activities in compost II remained at a higher level for a longer time, but they increased at a slower rate. Mineral content changes in the compost mass consisted primarily of an increase in N-NO3− concentration and a decrease in N-NH4+ and S-SO42− levels, especially in compost I. The concentration of mineral nitrogen and sulfur forms in compost water extracts was about 10–100 times lower than in the compost mass. At the end of composting, the amount of sulfates in the compost mass was 30 and 150 mg kg−1 dw in compost II and I, respectively. In this context, the composts obtained should be considered valuable for fertilizing soils poor in this component and for cultivating plants with high sulfate S demand.

Efficiency of vermicompost production and use in agriculture

The relevance of the study is due to the need to eliminate the environmental problems associated with the irrational use of chemical fertilizers in agriculture. Biohumus is an environmentally friendly natural fertilizer, which is produced by processing food waste ringworms, whose natural habitat is compost mass and not mineral soils. Thus, the production does not violate the flora and fauna and at the same time is environmentally friendly and waste-free. Practical significance of the study consists in the development of measures, the implementation of which will allow solving environmental problems caused by the irrational use of chemical fertilizers. As part of the study, the authors proposed using biohumus as a natural fertilizer, which allows, on the one hand, reducing the chemical effect on the soil cover, reducing the chemical elements content in finished agricultural products, eliminating the plants treatment with pesticides, and on the other hand, increasing the natural yield, developing immunity in plants of various species, and improving the physical properties of the soil layers.

Mixing Efficiency of Compost Tea Brewing Machines with Various Airlift Pump Air Jacket Structures and Air Injection Pressures

Compost tea is an organic agriculture product that is used as a bio-fertilizer and biopesticide in modern agriculture. It is produced from compost using various brewing machines. The compost must be well mixed with water to support optimal extraction of nutrients and microorganisms. Therefore, in this study, the mixing efficiencies of brewing machines equipped with six different structured airlift pumps operating at six different air injection pressures (8, 9, 10, 12, 14, and 16 kPa) were investigated via comparative trials of the compost liquid circulation and the electrical conductivity and data analysis. Designs with total hole areas of 0.09 cm2 achieved the highest compost liquid mass flow rates and good mixing efficiencies. In addition, air mass flow rates increased with the number of air injection holes at fixed pressures. Together, these data indicated that the best air jacket footpiece design in this study was A2, which contained eight holes with diameters of 1.2 mm. This design achieved the highest pump efficiency, mixing time, and liquid compost mass flow at most air pressures. This paper will help designers and manufacturers of this type of machinery.

Effects of initial C/N ratio on organic matter degradation of composting of rose oil processing solid wastes

This research study was aimed to investigate the degradability of organic substances of rose oil processing solid wastes mixed with separated dairy manure and straw. The experiment was conducted in 2014. Compost mixtures were prepared at five different C/N ratios of 16.52, 23.27, 27.48, 31.39, and 32.35 by keeping the moisture content (on a wet basis, %) between 67.76 and 74.87. Each mixture was replicated twice in composting reactors. To assess degradation rates changing with the initial C/N ratio, a first-order kinetic equation based on mass balance was utilized. Results showed that the highest decomposition rate was calculated as 0.03 kg kg−1 day−1. For each mixture, the compost mass ratio was also determined. The relationship between loss on dry matter and organic matter content and the initial C/N ratio were ascertained by using regression analysis applying Gaussian equation. According to the results, the maximum loss on dry matter and organic matter content was found to be 14.53 and 24.34%, while the corresponding initial C/N ratio was 29.50 and 24.25, respectively. It was concluded that the initial C/N ratio of the mixture could be greater than 30 in order to reduce nitrogen loss. Carbon loss was also expressed as a function of the initial C/N ratio by using regression analysis. An initial C/N ratio > 21.77 was suggested to reduce carbon loss for composting of rose oil processing solid wastes mixed with separated dairy manure and straw.