Kitchen Waste Composting Research Articles

Effects of the Ingredients on Maturity and Humification during Kitchen Waste Composting as Illustrated by Nuclear Magnetic Resonance

Kitchen waste (KW) production has risen considerably due to the increasing affluence of populations and a booming catering sector. If not properly disposed, KW can bring serious issues for the environment. Composting is widely used as an efficient method for the resource utilization of KW. In the present paper, the effects of different ratios of ingredients (corn straw: garden waste = 4:1, based on the dry mass) on maturity and humification during KW composting were investigated. The results showed that the nitrogen retention capacity of the treatments with a ratio of ingredients to KW of 1:2.5 and 1:5.0 was higher than that of other treatments. Additionally, it was found that the number of ingredients had an effect on the germination index (GI) during composting, and the final GI values of the four treatments were in the following order: 1:7.5 > 1:5.0 > 1:10.0 > 1:2.5. Nuclear magnetic resonance (NMR) showed that the organic matter (OM) content of each treatment increased after composting, and the maturity of the 1:2.5 and 1:5.0 treatments was higher than the other two treatments. Redundancy analysis (RDA) showed that the maturity and humification were correlated with moisture content, pH and NO3−-N during composting. This study concludes that the treatment with an ingredients to KW ratio of 1:5.0 was much more useful for KW composting, which is of importance to guide the disposal of KW.

Nitrogen retention and emissions during membrane-covered aerobic composting for kitchen waste disposal

The composting performance and nitrogen transformation during membrane-covered aerobic composting of kitchen waste were investigated. The aerobic composting products of the kitchen waste had a high seed germination index of ∼180%. The application of the membrane increased the mean temperature in the early cooling stage of composting by 4.5℃, resulted in a lower moisture content, and reduced the emissions of NH3 and N2O by 48.5% and 44.1%, respectively, thereby retaining 7.9% more nitrogen in the compost. The adsorption of the condensed water layer under inner-membrane was the reason for reducing NH3 emissions, and finite element modeling revealed that the condensed water layer was present throughout the composting process with a maximum thickness of ∼2 mm in the thermophilic stage. The reduction of N2O emissions was related to the micro-positive pressure in the reactor, which promoted the distribution of oxygen, thus weakening denitrification. In addition, the membrane cover decreased the diversity of the bacterial community and increased the diversity of ammonia-oxidizing strains. This study confirmed that membrane-covered composting was suitable for kitchen waste management and could be used as a strategy to mitigate NH3 and N2O emissions.

Integrating Life Cycle Assessment and Machine Learning to Enhance Black Soldier Fly Larvae-Based Composting of Kitchen Waste

Around 40% to 60% of municipal solid waste originates from kitchens, offering a valuable resource for compost production. Traditional composting methods such as windrow, vermi-, and bin composting are space-intensive and time-consuming. Black soldier fly larvae (BSFL) present a promising alternative, requiring less space and offering ease of handling. This research encompasses experimental data collection, life cycle assessment, and machine learning, and employs the Levenberg–Marquardt algorithm in an Artificial Neural Network, to optimize kitchen waste treatment using BSFL. Factors such as time, larval population, aeration frequency, waste composition, and container surface area were considered. Results showed that BSFL achieved significant waste reduction, ranging from 70% to 93% by weight and 65% to 85% by volume under optimal conditions. Key findings included a 15-day treatment duration, four times per day aeration frequency, 600 larvae per kilogram of waste, layering during feeding, and kitchen waste as the preferred feed. The larvae exhibited a weight gain of 2.2% to 6.5% during composting. Comparing the quality of BSFL compost to that obtained with conventional methods revealed its superiority in terms of waste reduction (50% to 73% more) and compost quality. Life cycle assessment confirmed the sustainability advantages of BSFL. Machine learning achieved high accuracy of prediction reaching 99.5%.

Regulating method of microbial driving the phosphorus bioavailability in factory composting

Phosphorus bioavailability is essential for assessing compost quality. However, the effects of microbial and environmental factors on potentially active phosphorus (H2O-P + NaHCO3-Pi) in factory compost have not been investigated. The findings indicated that chicken manure had significantly higher available phosphorus (AP) and H2O-P + NaHCO3-Pi throughout the composting process than kitchen waste (P < 0.05). Chicken manure compost also exhibited higher α-microbial diversity. Novibacillus, Marinococcaceae and Bacillales were the core bacteria involved in bioavailable phosphorus conversion in both composts. The core bacteria in kitchen waste compost had a broader range of phosphorus metabolism functions. Moreover, moisture and pH were the key environmental factors that significantly influenced the bioavailable phosphorus (P < 0.05). These findings provide a scientific foundation for regulating the composting process and improving phosphorus utilization efficiency.

Optimization of free air space to regulate bacterial succession and functions for alleviating gaseous emissions during kitchen waste composting

This study investigated the effects of free air space (FAS) (45%, 55%, 65%) on bacterial dynamics for gaseous emissions during kitchen waste composting. Results show that FAS increase from 45% to 65% elevated oxygen diffusivity to inhibit bacteria for fermentation (e.g. Caldicoprobacter and Ruminofilibacter) to reduce methane emission by 51%. Moreover, the increased FAS accelerated heat loss to reduce temperature and the abundance of thermophiles (e.g. Thermobifida and Thermobacillus) for aerobic chemoheterotrophy to mitigate ammonia emission by 32%. Nevertheless, the reduced temperature induced the growth of Desulfitibacter and Desulfobulbus for sulfate/sulfite respiration to boost hydrogen sulphide emission. By contrast, FAS at 55% achieved the highest germination index and favored the proliferation of nitrifiers and denitrifiers (e.g. Roseiflexus and Steroidobacter) to improve nitrate availability, thus slightly enhancing nitrous oxide emission. Thus, FAS at 55% exhibits the optimal performance for gaseous emission reduction and maturity enhancement in kitchen waste composting.

Dynamics of antibiotic resistance genes and bacterial community during pig manure, kitchen waste, and sewage sludge composting

Organic solid wastes (OSWs) are important reservoirs for antibiotic resistance genes (ARGs). Aerobic composting transforms OSWs into fertilizers. In this study, we investigated ARGs dynamics and their driving mechanisms in three OSW composts: pig manure (PM), kitchen waste (KC), and sewage sludge (SG). The dominant ARGs were different in each OSW, namely tetracycline, aminoglycoside, and macrolide resistance (PM); tetracyclines and aminoglycosides (KC); and sulfonamides (SG). ARGs abundance decreased in PM (71%) but increased in KC (5.9-fold) and SG (1.3-fold). Interestingly, the ARGs abundance was generally similar in all final composts, which was contributed to the similar bacterial community in final composts. In particular, sulfonamide and β-lactam resistant genes removed (100%) in PM, while sulfonamide in KC (38-fold) and tetracycline in SG (5-fold) increased the most. Additionally, ARGs abundance rebounded during the maturation period in all treatments. Firmicutes, Proteobacteria, and Actinobacteria were the main ARGs hosts. Several persistent and high-risk genes included tetW, aadA, aadE, tetX, strB, tetA, mefA, intl1, and intl2. The structural equation models showed ARGs removal was mainly affected by physicochemical parameters and bacterial communities in PM, the ARGs enrichment in KC composting correlated with increased mobile genetic elements (MGEs). In general, thermophilic aerobic composting can inhibit the vertical gene transfer (VGT) of pig manure and horizontal gene transfer (HGT) of sludge, but it increases the HGT of kitchen waste, resulting in a dramatic increase of ARGs in KC compost. More attention should be paid to the ARGs risk of kitchen waste composting.

Study on the Effect of Kitchen Waste Compost Substrate on the Cultivation of &lt;i&gt;Brassica chinensis&lt;/i&gt; L.

Study on the Effect of Kitchen Waste Compost Substrate on the Cultivation of &lt;i&gt;Brassica chinensis&lt;/i&gt; L.

Addition of exogenous microbial agents increases hydrogen sulfide emissions during aerobic composting of kitchen waste by improving bio-synergistic effects

The effect of microbial agents (MA) on hydrogen sulfide (H2S) emissions in the compost is still a controversial issue. This study examined the effects and microbial mechanisms of MA on H2S emissions during the composting of kitchen waste. The results showed that MA addition can promote sulfur conversion to elevate H2S emissions by approximately 1.6 ∼ 2.8 times. Structural equations demonstrated that microbial community structure was the dominant driver on H2S emissions. Agents reshaped the compost microbiome, showing more microorganisms participated in sulfur conversion, and enhanced the connection between microorganisms and functional genes. The relative abundance of keystone species associated with H2S emissions increased after adding MA. Particularly, the sulfite and sulfate reduction processes were intensified, as evidenced by an increasing in the abundance and pathways cooperation of sat and asrA after MA addition. The outcome provides deeper insights into MA on regulating the mitigation of H2S emissions in compost.

Synergistic effects of chemical additives and mature compost on reducing H2S emission during kitchen waste composting

Additives could improve composting performance and reduce gaseous emission, but few studies have explored the synergistic of additives on H2S emission and compost maturity. This research aims to make an investigation about the effects of chemical additives and mature compost on H2S emission and compost maturity of kitchen waste composting. The results showed that additives increased the germination index value and H2S emission reduction over 15 days and the treatment with both chemical additives and mature compost achieved highest germination index value and H2S emission reduction (85%). Except for the treatment with only chemical additives, the total sulfur content increased during the kitchen waste composting. The proportion of effective sulfur was higher with the addition of chemical additives, compared with other groups. The relative abundance of H2S-formation bacterial (Desulfovibrio) was reduced and the relative abundance of bacterial (Pseudomonas and Paracoccus), which could convert sulfur-containing substances and H2S to sulfate was improved with additives. In the composting process with both chemical additives and mature compost, the relative abundance of Desulfovibrio was lowest, while the relative abundance of Pseudomonas and Paracoccus was highest. Taken together, the chemical additives and mature compost achieved H2S emission reduction by regulating the dynamics of microbial community.

Kitchen Waste Compost’s Impact on Rice Quality, Yield, and Soil Environment

Kitchen Waste Compost’s Impact on Rice Quality, Yield, and Soil Environment

Employing salt-tolerant bacteria Serratia marcescens subsp. SLS for biodegradation of oily kitchen waste

The high oil and salt content of kitchen waste (KW) inhibit bioconversion and humus production. To efficiently degrade oily kitchen waste (OKW), a halotolerant bacterial strain, Serratia marcescens subsp. SLS which could transform various animal fats and vegetable oils, was isolated from KW compost. Its identification, phylogenetic analysis, lipase activity assays, and oil degradation in liquid medium were assessed, and then it was employed to carry out a simulated OKW composting experiment. In liquid medium, the 24 h degradation rate of mixed oils (soybean oil: peanut oil: olive oil: lard = 1:1:1:1, v/v/v/v) was up to 87.37% at 30 °C, pH 7.0, 280 rpm, 2% oil concentration and 3% NaCl concentration. The ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS) method demonstrated that the mechanism of SLS strain metabolizing long-chain triglycerides (TAGs) (C53–C60), especially the biodegradation of TAG (C18:3/C18:3/C18:3) by the strain can reach more than 90%. Degradation of 5, 10, 15% concentrations of total mixed oil were also calculated to be 64.57, 71.25, 67.99% respectively after a simulated composting duration of 15 days. The results suggest that the isolated strain of S. marcescens subsp. SLS is suitable for OKW bioremediation in high NaCl concentration within a reasonably short period of time. The findings introduced a salt-tolerant and oil-degrading bacteria, providing insights into the mechanism of oil biodegradation and offering new avenues of study for OKW compost and oily wastewater treatment.

The Effect of Initial Carbon to Nitrogen Ratio on Kitchen Waste Composting Maturity

A home electrical composter has arisen as a popular tool to expedite the lengthy composting process. It has been conveniently selected as a compost producer in kitchen households and is especially favoured in urbanized settings. The generated composts from the electrical composter, however, are still found to be immature and would require additional curing. The quality of the compost can be improved by investigating the initial carbon-to-nitrogen ratio (C/N ratio) of kitchen waste. It is, therefore, the aim of this paper to determine the optimum initial C/N ratio by preparing two primary samples: with and without soil. Samples of 10:1, 15:1, 20:1, 25:1, 30:1, and 35:1 C/N ratios were fed into the electrical composter and allowed to cure for 4 weeks. The six main samples were further divided into sub-samples for replications. The phytotoxicity levels and maturity of the produced compost were assessed in terms of the germination index (GI), using a seed germination test. In addition, statistical analyses using box plots and T-distributed Stochastic Neighbour Embedding (T-SNE) were carried out to observe the root growths’ variability and to deduce any significant clusters amongst the samples. The results have shown that samples with and without soil performed better with C/N ratios of 10:1 and 25:1 and with GI values of 16.2 and 31.8, respectively. The results also indicate the presence of a substantial level of phytotoxins within the samples, even after four weeks of curing.

Succession of microbial communities with VOC changes during composting process

The kitchen waste compost treatment of diesel contaminated soil has the advantages of good bioremediation effect and low treatment cost. However, through understanding the mechanism of microbial degradation of diesel, the disadvantage of biological treatment time in the composting process is too time-consuming. The research results showed that the evolution of microbial communities was affected by physicochemical parameters in the composting process. During the heating period, it was found that Lactobacillus sakei and Escherichia coli were acid producing bacteria. Pseudomonas putida GB-1 is a terpenoid producing bacterium. Bacillus sp. was found to be aldehyde and sulfide producing bacteria during high temperature composting. Brevibacillus borstenensis and Low G + C Gram positive bacteria are ammonia producing bacteria. The microbial degradation mechanism could be deduced according to the VOCs change in compost gas, and the strategies to promote the efficiency of biological treatment in the composting process were provided for reference.

Greenhouse gas emissions from agricultural soil amended with kitchen compost of varying ages

ABSTRACT Although the use of kitchen waste compost is very common, GHG emissions from soil amended with kitchen waste compost have not been studied. This study aimed to determine the effects of kitchen compost age and application rates on GHG emissions to identify optimal compost management. Soil samples mixed with kitchen waste compost at three different ages: 1 month (1M), 2 months (2M), and 3 months (3M) at two application rates (1% and 2% w/w) were incubated at 25°C for 28 days under aerobic conditions. Emissions of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) were determined on days 3, 7, 14, 21, and 28. Results showed that N2O and CO2 emissions decreased with compost age (p < 0.05). Increased application rates of compost led to increased CO2 emissions and suppression of N2O emissions. Furthermore, CH4 was emitted from soil amended with kitchen compost even under aerobic conditions. This study suggests that 3M kitchen waste compost is optimal in terms of GHG emissions upon application to soil under aerobic conditions.

Hydrothermal pretreatment and compound microbial agents promoting high-quality kitchen waste compost: Superior humification degree and reduction of odour

Present study investigated the effects of hydrothermal pretreatment (HTP) and addition of compound microbial agent (CMA) on humification, odour generation and metabolism functions of bacterial communities during composting of kitchen waste (KW). Surprisingly, HTP and CMA addition treatment could promote the humification of compost and the control of odour units in contrast to the control (without HTP and CMA addition). The humic acid to fulvic acid ratio of end compost increase by 187.30 %, while humification index (HIX) increased by 18.87 %. 3D-EEM fluorescence spectroscopy of dissolved organic matter (DOM) demonstrated that it facilitated the synthesis of humified compounds and the decomposition of biodegradable compounds. Moreover, the SUVA254, SUVA280 and E253/E203 increased by 118.6 %, 115.25 % and 42.11 % after HTP and CMA addition indicating an increase in aromatic carbon abundance. VFAs had the higher degradation rate (84.91 %) than other treatments (57.46–77.72 %). Meanwhile, the main contributor to the malodorous odour was isovaleric acid, followed by butyric acid and acetic acid during composting. Mantel test indicated that the humification degree was significantly influenced by environmental parameters (temperature, pH, etc.) and metabolic products (HA, DOC and VFAs). Metagenomic analysis indicated that the biodegradation processes at the thermophilic stage were controlled mainly through genes involved in microbial metabolism. HTP and CMA addition was an eco-friendly and efficient strategy to reduce odour emission and improve the compost quality.

Feeding Hungry Soils of Northern Ghana using Kitchen Waste as Compost

The soils of northern Ghana are mostly undeveloped and characterized by poor fertility and productivity especially towards the Sahara desert. The issue of climate change affecting rainfall patterns and high cost of fertilizers further exacerbates issues surrounding productive soils and food security. Waste separation is not a common practice in both rural and urban areas of the country. Domestic composting of kitchen waste is therefore not a popular practice amongst small holder farmers in the area, as they mostly rely on subsidized fertilizers and waste from livestock and other animals to improve their soils. The Regentropfen College of Applied Sciences in Ghana has however mapped out a research plan that sought to use kitchen waste from their students’ hostel and model schools to promote nutrient cycling in their ecosystem to produce 100% organic food products to sustain its community. The intervention will eventually be scaled up in the immediate community (Bongo district) after implementation. The main ideology of this endeavour is to promote sustainable agriculture, reduce greenhouse gas emissions and promote sustainable livelihoods for all. This article is therefore a mini review on the subject matter.

Effect of moisture content, aeration rate, and C/N on maturity and gaseous emissions during kitchen waste rapid composting

To determine factors affecting compost maturity and gaseous emissions during the rapid composting of kitchen waste, an orthogonal test was conducted with three factors: moisture content (MC) (55%, 60%, 65%), aeration rate (AR) (0.3,0.6 and 0.9 L·kg−1DM·min−1) and C/N ratio (21, 24, 27). The results showed that the importance of factors affecting compost maturity was: C/N > AR > MC, optimal conditions were: C/N of 24, AR of 0.3 L·kg−1DM·min−1and MC of 65%. For gaseous emissions, the sequence of essential factors affecting NH3 emissions was: C/N > MC > AR, and the optimal parameters for NH3 reduction were: C/N of 27, MC of 65%, and AR of L·kg−1DM·min−1. The important factors affecting N2O and H2S emissions are both: MC > C/N > AR, while their best parameters were different. The optimal parameters for N2O emission reduction were MC of 60%, AR of 0.3 L·kg−1DM·min−1 and C/N of 24, while these for H2S were MC of 55%, AR of 0.3 L·kg−1DM·min−1 and C/N of 21. The C/N mainly affected the compost maturity and AR further affected the maturity and pollutant gas emissions by influencing the temperature and O2 content. Considering comprehensively the maturity and gaseous reduction, the optimal control parameters were: MC of 60%–65%, AR of L·kg−1DM·min−1, and C/N of 24–27.

Influence of kitchen waste compost and chemical fertilizer on the growth and yield of tomato (Solanum lycopersicum)

A pot experiment was conducted to evaluate the effect of kitchen waste compost (KWC) and NPK fertilizers on the growth and yield of tomato. It was laid out in a completely randomized block design (CRBD) using 25 treatments having 3 replications each. Agronomic parameters of the growth and yield of tomato were recorded at 15, 30, 45, and 60 days interval. The highest growth and yield parameter found with 60 days. The tallest plant height (57 cm) was recorded in T13(N120P60K80 kg ha-1 + 2.5ton KWC ha-1). Highest number of leaf found (17 per plant) in T18 (N30P15K20 kg ha-1 + 7.5 ton KWC ha-1) and T23 (N60P30K40 kg ha-1 + 10 ton KWC ha1. The length of midrib (22 cm) inT3 (5ton KWC ha-1) and dry weight of midrib (1.46 g plant-1) obtained topmost in T6(N30P15K20 kg ha-1). The girth of plants (1.4 cm) in T14: (N30P15K20 kg ha-1 + 5 ton KWC ha-1, and leaf area (5.61 cm2) in T2 (2.5 ton KWC ha-1). Total fresh weight of leaf, root and stem (60.3 g plant1) and dry weight of leaf, root and stem (21.91 g plant-1) were superior inT24(N90P45K60 kg ha-1 + 10 ton KWC ha-1), number of fruit per plant (10) inT5(10 ton KWC ha-1) and longest fruit (7.5 cm) inT5(10 ton KWC ha-1). Maximum fresh weight of tomato fruit (13.48 g plant-1) produces in T24 (N90P45K60 kg ha-1 + 10 ton KWC ha-1) and dry weight (5.32 g plant-1) in T20 (N90P45K60 kg ha-1 + 7.5 ton KWC ha-1). The findings revealed that KWC with NPK T24 (N90P45K60 kg ha-1 + 10 ton KWC ha-1) could be suggested to use for the maximum growth and yield of tomato. This trial has also been created the evidence that kitchen waste may be an alternative source of organic materials to produce tomato. J. Biodivers. Conserv. Bioresour. Manag. 2022, 8(1): 81-90

Thermophilic semi-continuous composting of kitchen waste: Performance evaluation and microbial community characteristics

This study evaluated the feasibility, system stability, and microbial community succession of thermophilic semi-continuous composting of kitchen waste (KW). The results revealed that treatment performance was stable at a 10 % feeding ratio, with an organic matter (OM) degradation efficiency of 81.5 % and seed germination index (GI) of 50.0 %. Moreover, the OM degradation efficiency and GI were improved to 83.4 % and 70.0 %, respectively, by maintaining an optimal compost moisture content (50–60 %). However, feeding ratios of ≥ 20 % caused deterioration of the composter system owing to OM overloading. Microbial community analysis revealed that Firmicutes, Actinobacteria, Chloroflexi, Proteobacteria, and Gemmatimonadetes were dominant. Additionally, moisture regulation significantly increased the Proteobacteria abundance by 57.1 % and reduced the Actinobacteria abundance by 57.8 %. Moreover, network analysis indicated that the bacterial community stability and positive interactions between genera were enhanced by moisture regulation. This information provides a useful reference for practical KW composting treatment in the semi-continuous mode.

Effect of hydrothermal pretreatment and compound microbial agents on compost maturity and gaseous emissions during aerobic composting of kitchen waste

Though aerobic composting is commonly used in kitchen waste (KW) disposal, the high-oil and high-salt characteristics of KW could affect composting efficiency and lead to the land using risk of produced fertilizer. The impact of hydrothermal pretreatment (HTP) and addition of compound microbial agent (CMA) on compost maturity, greenhouse gas (GHGs) emissions and bacterial community during the kitchen waste composting were evaluated in the present work. Results indicated that N2O, CH4 and CO2 emissions from treatment by HTP and CMA addition were reduced by 82.72%, 13.77% and 20.78 %, respectively, comparing with the control (without HTP and without CMA addition). The seed germination index (GI) value of the HTP and CMA addition treatment was 1.03 and had the highest maturity in all treatments. Furthermore, the bacterial community analysis indicated that CMA inoculation could increase the relative abundance of genus Bacillus at the thermophilic stage of composting to accelerate organic biodegradation. This work provided important insight into mitigating GHGs emissions and improving compost quality in kitchen waste composting.