VFA and ammonia from residential food waste as indicators of odor potential

Research was conducted to determine suitable chemical parameters as indicators of odor from decomposing food wastes. Prepared food scraps were stored in 18 l plastic buckets (2 kg wet weight each) at 20 °C and 8 °C to reproduce high and low temperature conditions. After 1, 3, 7, 10 and 14 days of storage, the odor from the buckets were marked to an intensity scale of 0 (no odor) to 5 (intense) and the corresponding leachate analyzed for volatile fatty acids, ammonia and total organic carbon. A linear relationship between odor intensity and the measured parameter indicates a suitable odor indicator. Odor intensified with longer storage period and warmer surroundings. The study found ammonia and isovaleric acid to be promising odor indicators. For this food waste mixture, offensive odors were emitted if the ammonia and isovaleric acid contents exceeded 360 mg/l and 940 mg/l, respectively.     

Evaluation of a classification method for biodegradable solid wastes using anaerobic degradation parameters

We studied the biochemical and anaerobic degradation characteristics of 29 types of materials to evaluate the effects of a physical composition classification method for degradable solid waste on the computation of anaerobic degradation parameters, including the methane yield potential (L₀), anaerobic decay rate (k), and carbon sequestration factor (CSF). Biochemical methane potential tests were conducted to determine the anaerobic degradation parameters of each material. The results indicated that the anaerobic degradation parameters of nut waste were quite different from those of other food waste and nut waste was classified separately. Paper was subdivided into two categories according to its lignin content: degradable paper with lignin content of <0.05 g g VS^?1, and refractory paper with lignin content >0.15 g g VS^?1. The L₀, k, and CSF parameters of leaves, a type of garden waste, were similar to those of grass. This classification method for degradable solid waste may provide a theoretical basis that facilitates the more accurate calculation of anaerobic degradation parameters.     

Impact of nitrate-enhanced leachate recirculation on gaseous releases from a landfill bioreactor cell

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N₂O emissions. During several weeks, we monitored gas concentrations in the landfill gas collection system as well as surface gas releases with a series of seven static chambers. These devices were directly connected to a gas chromatograph coupled to a flame ionisation detector and an electron capture detector (GC-FID/ECD) placed directly on the field. Measurements were performed before, during and after recirculation of raw leachate and nitrate-enhanced leachate. Raw leachate recirculation did not have a significant effect on the biogas concentrations (CO₂, CH₄ and N₂O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N₂O concentrations in the gas collected from the recirculation trench (100-fold increase from 0.2 ppm to 23 ppm). In the common gas collection system however, this N₂O increase was no more detectable because of dilution by gas coming from other cells or ambient air intrusion. Surface releases through the temporary cover were characterized by a large spatial and temporal variability. One automated chamber gave limited standard errors over each experimental period for N₂O releases: 8.1 ± 0.16 mg m^?2 d^?1 (n = 384), 4.2 ± 0.14 mg m^?2 d^?1 (n = 132) and 1.9 ± 0.10 mg m^?2 d^?1 (n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N₂O gaseous surface releases and recirculation events were evidenced. Estimated N₂O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection.     

Fertilizer and sanitary quality of digestate biofertilizer from the co-digestion of food waste and human excreta

This research was aimed at assessing the fertilizer quality and public health implications of using digestate biofertilizer from the anaerobic digestion of food wastes and human excreta. Twelve (12) kg of food wastes and 3 kg of human excreta were mixed with water in a 1:1 w/v to make 30-l slurry that was fed into the anaerobic digester to ferment for 60 days at mesophilic temperature (22–31 °C). Though BOD, COD, organic carbon and ash content in the feedstock were reduced after anaerobic digestion by 50.0%, 10.6%, 74.3% and 1.5% respectively, nitrogen, pH and total solids however increased by 12.1%, 42.5% and 12.4% respectively. The C/N ratios of the feedstock and compost are 135:1 and 15.8:1. The residual total coliforms of 2.10 × 10⁸ CFU/100 ml in the digestate was above tolerable limits for direct application on farmlands. Microbial analysis of the digestate biofertilizer revealed the presence of Pseudomonas, Klebsiella, Clostridium, Bacillus, Bacteroides, Penicillum, Salmollena, and Aspergillus. Klebsiella, Bacillus, Pseudomonas, Penicillum and Aspergillus can boost the efficiency of the biofertilizer through nitrogen fixation and nutrient solubility in soils but Klebsiella again and Salmollena are potential health risks to end users. Further treatment of the digestate for more efficient destruction of pathogens is advised.     

Temperature and deactivation of microbial faecal indicators during small scale co-composting of faecal matter

Small scale co-composting of faecal matter from dry toilet systems with shredded plant material and food waste was investigated in respect to heat development and deactivation of faecal indicators under tropical semiarid conditions. Open (uncovered) co-composting of faecal matter with shredded plant material alone did not generate temperatures high enough (<55 °C) to reduce the indicators sufficiently. The addition of food waste and confinement in chambers, built of concrete bricks and wooden boards, improved the composting process significantly. Under these conditions peak temperatures of up to 70 °C were achieved and temperatures above 55 °C were maintained over 2 weeks. This temperature and time is sufficient to comply with international composting regulations. The reduction of Escherichia coli, Enterococcus faecalis and Salmonella senftenberg in test containment systems placed in the core of the compost piles was very efficient, exceeding 5 log₁₀-units in all cases, but recolonisation from the cooler outer layers appeared to interfere with the sanitisation efficiency of the substrate itself. The addition of a stabilisation period by extending the composting process to over 4 months ensured that the load of E. coli was reduced to less than 10³ cfu^?g and salmonella were undetectable.     

Comparison of recycling outcomes in three types of recycling collection units

Commercial institutions have many factors to consider when implementing an effective recycling program. This study examined the effectiveness of three different types of recycling bins on recycling accuracy by determining the percent weight of recyclable material placed in the recycling bins, comparing the percent weight of recyclable material by type of container used, and examining whether a change in signage increased recycling accuracy. Data were collected over 6 weeks totaling 30 days from 3 different recycling bin types at a Midwest University medical center. Five bin locations for each bin type were used. Bags from these bins were collected, sorted into recyclable and non-recyclable material, and weighed. The percent recyclable material was calculated using these weights. Common contaminates found in the bins were napkins and paper towels, plastic food wrapping, plastic bags, and coffee cups. The results showed a significant difference in percent recyclable material between bin types and bin locations. Bin type 2 was found to have one bin location to be statistically different (p = 0.048), which may have been due to lack of a trash bin next to the recycling bin in that location. Bin type 3 had significantly lower percent recyclable material (p < 0.001), which may have been due to lack of a trash bin next to the recycling bin and increased contamination due to the combination of commingled and paper into one bag. There was no significant change in percent recyclable material in recycling bins post signage change. These results suggest a signage change may not be an effective way, when used alone, to increase recycling compliance and accuracy. This study showed two or three-compartment bins located next to a trash bin may be the best bin type for recycling accuracy.     

Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions

Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this practice may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seeds of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37 °C) and thermophilic (55 °C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55 °C) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still maintained low levels (～1%) of germination ability after 1 week. Chenopodium album was the only weed species which survived 1 week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55 °C, no Ascaris eggs survived more than 3 h of incubation. Incubation at 37 °C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests.     

Thermogravimetric analysis and kinetic study on large particles of printed circuit board wastes

Pyrolysis of large printed circuit board (PCB) waste particle was conducted on a specially designed laboratory-scale thermobalance (Macro-TG) with sample loading of 30 g under dynamic nitrogen atmosphere. The effects of heating rate (10, 15, 20 and 25 °C min^?1) and particle size (1 mm × 1 mm, 5 mm × 5 mm, 10 mm × 10 mm and 10 mm × 20 mm) were examined. To compare the different decomposition behavior of fine and large one, the thermal decomposition of PCB waste powder (approximately 5 mg) was also performed on a thermogravimetric analyzer (common TG) under various heating rates (10, 15, 20 and 40 °C min^?1) and particle size ranges (0.198–0.165 mm, 0.165–0.074 mm, 0.074–0.055 mm and 0.055–0.047 mm). Experimental results show that large particle has a pyrolysis reaction retardancy compared to fine one. The distributed activation energy model was used to study the pyrolysis kinetics. It was found that during pyrolysis process, values of frequency factor (k₀) changed with different activation energy (E) values. On common TG, the E values range from 156.95 to 319.37 kJ mol^?1 and k₀ values range from 2.67 × 10¹³ to 2.24 × 10²⁷ s^?1. While, on Macro-TG, the range of E was 31.48–41.26 kJ mol^?1 and of the frequency factor was 19.80–202.67 s^?1.     

An analysis of the composition and metal contamination of plastics from waste electrical and electronic equipment (WEEE)

The compositions of three WEEE plastic batches of different origin were investigated using infrared spectroscopy, and the metal content was determined with inductively coupled plasma. The composition analysis of the plastics was based mainly on 14 samples collected from a real waste stream, and showed that the major constituents were high impact polystyrene (42 wt%), acrylonitrile–butadiene–styrene copolymer (38 wt%) and polypropylene (10 wt%). Their respective standard deviations were 21.4%, 16.5% and 60.7%, indicating a considerable variation even within a single batch. The level of metal particle contamination was found to be low in all samples, whereas wood contamination and rubber contamination were found to be about 1 wt% each in most samples. In the metal content analysis, iron was detected at levels up to 700 ppm in the recyclable waste plastics fraction, which is of concern due to its potential to catalyse redox reactions during melt processing and thus accelerate the degradation of plastics during recycling. Toxic metals were found only at very low concentrations, with the exception of lead and cadmium which could be detected at 200 ppm and 70 ppm levels, respectively, but these values are below the current threshold limits of 1000 ppm and 100 ppm set by the Restriction of Hazardous Substances directive.     

What is the acceptable margin of error for the oxygen uptake method in evaluating the reactivity of organic waste?

The acceptable margin of error for the organic waste reactivity measured by the oxygen uptake method was assessed. Oxygen uptake was determined by the Dynamic Respiration Index (DRI) (mgO₂/kgVS h). The composed uncertainty (uC) of the experimental set up used for the DRI test was evaluated and the uncertainty (u) of all the components of the apparatus was evaluated. A procedure for calculating the uC of the apparatus is proposed. The components affecting the uC of the DRI to a more significant extent were the one of the oxygen mass rate and the u of the amount of VS in the sample analyzed. For a confidence level of 99.73%, the extended uC (UC) interval for a DRI = 1024 mgO₂/kgVS h was ±440 mgO₂/kgVS h, whereas for a DRI = 3489 mgO₂/kgVS h, the UC interval was ±1288 mgO₂/kgVS h. When oxygen consumption and VS content become lower than 600 mgO₂/h and 0.9 kg, respectively, the UC interval is similar to the measured DRI.     

Recovery of lithium and cobalt from waste lithium ion batteries of mobile phone

In view of the stringent environmental regulations, availability of limited natural resources and ever increasing need of alternative energy critical elements, an environmental eco-friendly leaching process is reported for the recovery of lithium and cobalt from the cathode active materials of spent lithium-ion batteries of mobile phones. The experiments were carried out to optimize the process parameters for the recovery of lithium and cobalt by varying the concentration of leachant, pulp density, reductant volume and temperature. Leaching with 2 M sulfuric acid with the addition of 5% H₂O₂ (v/v) at a pulp density of 100 g/L and 75 °C resulted in the recovery of 99.1% lithium and 70.0% cobalt in 60 min. H₂O₂ in sulfuric acid solution acts as an effective reducing agent, which enhance the percentage leaching of metals. Leaching kinetics of lithium in sulfuric acid fitted well to the chemical controlled reaction model i.e. 1 ? (1 ? X)^1/3 = k_ct. Leaching kinetics of cobalt fitted well to the model ‘ash diffusion control dense constant sizes spherical particles’ i.e. 1 ? 3(1 ? X)^2/3 + 2(1 ? X) = k_ct. Metals could subsequently be separated selectively from the leach liquor by solvent extraction process to produce their salts by crystallization process from the purified solution.     

Phytoremediation of landfill leachate and compost wastewater by irrigation of Populus and Salix: Biomass and growth response

A pot experiment is described with a fast-growing poplar clone and two native willows (Populus deltoides Bartr. cl. I-69/55 (Lux)), Salix viminalis L. and Salix purpurea L.), irrigated with landfill leachate and compost wastewater over a 1-year growing period. The use of leachate resulted in up to 155% increased aboveground biomass compared to control water treatments and in up to 28% reduced aboveground biomass compared to a complete nutrient solution. The use of compost wastewater resulted in up to 62% reduced aboveground biomass compared to the control treatments and in up to 86% reduced aboveground biomass compared to the complete nutrient solution. Populus was the most effective in biomass production due to the highest leaf production, whereas S. purpurea was the least effective in biomass accumulation, but less sensitive to high ionic strength of the irrigation water compared to S. viminalis. The results showed a high potential for landfill leachate application (with up to 2144 kg N ha^?1, 144 kg P ha^?1, 709 kg K ha^?1, 1010 kg Cl ha^?1, and 1678 kg Na ha^?1 average mass load in the experiment). High-strength compost wastewater demonstrated less potential for application as irrigation and fertilization source even in high water-diluted treatments (1:8 by volume).     

Optimization of thermo-chemical pretreatment and enzymatic hydrolysis of kitchen wastes

The use of abundant waste materials with high carbohydrate content may contribute substantially to reduction of biofuels production cost. The present study aimed at optimizing the combined effect of thermo-chemical pretreatment and enzymatic hydrolysis of kitchen wastes (KW) for maximizing the production of fermentable soluble sugars. To this end, acid pretreatment of KW samples was performed with hydrochloric acid (0–3% HCl) at 30–100 °C for 0–120 min treatment time. Alternatively, alkaline pretreatment of KW samples was performed with potassium hydroxide solution (0–11%) at constant temperature and time (0 °C and 20 min, respectively). KOH pretreatment at such conditions targets to degrade the resistant starch of KW samples. Both acid and alkaline pretreatments were followed by addition of variable levels of enzyme dosage (0–3.6% v/v α-amylase and 0–3.2% v/v amyloglucosidase-AMG) at constant pH, temperature and time (pH = 5, T = 50 °C and t = 30 min, respectively). Based on our results, glucose concentration increased by ～300% after pretreatment with either acid or KOH in combination with enzymatic hydrolysis (2% HCl, 85 °C, 80 min, 0.1% α-amylase, AMG, and 1% KOH, 0 °C, 20 min, 1.1% α-amylase, 0.4% AMG) compared to raw (untreated) KW. Estimating the different Y_G yields at KW loading of 5%, an increase of 192% and 121% for total soluble monosugars and total soluble sugars, respectively, was succeeded compared to untreated KW. The effect of solids loading on the obtained sugar yields using the optimum conditions for thermo-chemical pretreatment followed by enzymatic hydrolysis was also tested resulting to 27.5% increase of the soluble glucose yield when half of the solids loading (2.5%) was used. A decrease of total soluble sugars yield by 32.2% was observed when solely acid hydrolysis at optimum conditions from our previous study was applied at 30% solids loading.     

The usability of the IR,RAC and MRI indices of heavy metal distribution to assess the environmental quality of sewage sludge composts

To assess the environmental quality of compost, it is insufficient to use only total metal concentration. Therefore in this study, the stability of metals in compost and the environmental risk they pose were assessed by three indices that have been proposed for soils or sediments: the I_R, the RAC and the MRI. In mature composts, the highest bonding intensity was for Ni (0.79 < I_R < 0.93), then for Cu (0.56 < I_R < 0.65) and Pb (0.55 < I_R < 0.73), and the lowest for Zn (0.19 < I_R < 0.25). Although, both the I_R and the RAC are useful indices for evaluating the mobility of metals, they do not take into account their toxicity. Therefore, the overall classification of compost should also include the MRI, at which metal toxicity from the most available fractions is considered. Based on the MRI ranged between 10.0 and 11.6, all composts evaluated posed a low risk.     

Impacts of industrial waste resources on maize (Zea mays L.) growth,yield, nutrients uptake and soil properties

Discharging untreated highly acidic (pH < 4.0), organic and nutrients rich monosodium glutamate wastewater (MW), and highly alkaline (pH > 10.0) paper-mill wastewater (PW) causes environmental pollution. When acidity of MW neutralized (pH 6.5 ± 0.1) with PW and lime (treatments represented as MW + PW and MW + Lime), then MW may be utilized as a potential source of nutrients and organic carbon for sustainable food production. Objectives of this study were to compare the effects of PW and lime neutralized MW and chemical fertilizers on maize (Zea mays L. cv. Snow Jean) plant growth, yield, nutrients uptake, soil organic matter and humic substances. The field experiment was carried out on maize using MW at 6000 L ha^?1. Impacts of the MW application on maize crop and soil properties were evaluated at different stages. At harvest, plant height, and plant N and K uptake were higher in MW treatment. Leaf area index at 60 days after sowing, plant dry matter accumulation at harvest, and kernels ear^?1 and 100-kernel weight were higher in MW + Lime treatment. Kernel N, P, K, Mn, Fe and Zn, and plant Zn uptake were highest in MW + Lime. Plant Fe uptake, and soil organic matter and humic substances were highest in MW + PW. The MW + PW and MW + Lime treatments exhibited comparable results with chemically fertilized treatment. The MW acidity neutralized with lime showed positive impacts on growth, yield and nutrients uptake; nevertheless, when MW pH neutralized with PW has an additional benefit on increase in soil organic matter and humic substances.     

Phytotoxicity of landfill leachate on willow – Salix amygdalina L.

Because of low investment and operational costs, interest is increasing in the use of willow plants in landfill leachate disposal. Toxic effects of leachate on the plants should be avoided in the initial period of growth and phytotoxicological testing may be helpful to select appropriate leachate dose rates. The aim of this study was to determine the phytotoxicity of landfill leachate on young willow (Salix amygdalina L.) cuttings, as a criterion for dose rate selection in the early phase of growth. Over a test period of 6 weeks plants were exposed to six concentrations of landfill leachate solutions (0%; 6.25%; 12.5%; 25%; 50% and 100%), under two different regimes. In regime A willow plants were cultivated in leachate solution from the beginning, whereas in regime B they were grown initially in clean water for 4 weeks, after which the water was exchanged for leachate solutions. The lowest effective concentration causing toxic effects (LOEC) was calculated (p < 0.05). In regime A LOEC was between 5.44% and 6.50% of leachate concentration, but slightly higher in regime B (5.32–6.59%). Willow plants were able to survive in landfill leachate solutions with electrical conductivity (EC) values up to 5.0 mS/cm in regime A, whereas in regime B plants were killed when EC exceeded 3.0 mS/cm. This indicates an ability of willow plants to tolerate higher strengths of landfill leachate if they are cultivated in such concentrations from the beginning.     

Nutrient release from bisulfate-amended phytase-diet poultry litter under simulated weathering conditions

Poultry litter generated on the Delmarva Peninsula is from phytase-modified bird diet and bisulfate amendment. To establish agronomic application rates in conservation tillage systems, bisulfate-amended phytase-diet poultry litter was investigated for its nutrient release kinetics and supply capacity under simulated weathering conditions. Delmarva poultry litter was packed in PVC columns (15 cm i.d. × 25 cm height) to a depth of 5 cm and leached intermittently with 600 mm of water for 190 days. Concentrations of various nutrients in leachate were analyzed and nutrient release kinetics were modelled. Poultry litter leachate contained high contents of dissolved organic carbon (DOC, 35–11,800 mg L^?1), nitrogen (N 6–2690 mg L^?1), phosphorus (P 45–225 mg L^?1), potassium (K 20–6060 mg L^?1), and other nutrients. Release of the nutrients occurred primarily in the starting 5 weeks and mostly followed a first order Exponential-Rise-to-Maximum model. Under the specified conditions, the poultry litter demonstrated a nutrient supply capacity of 11.7 kg N Mg^?1, 5.4 kg P Mg^?1, and 36.8 kg K Mg^?1. Release of the potentially plant-available N and K was nearly finalized within 190 days of leaching/weathering, but it would require two years for full release of the leachable P. The results indicate that with consideration of field conditions, surface application of bisulfate-amended phytase-diet Delmarva poultry litter at recommended 6.6 Mg ha^?1 to conservation tillage systems would largely provide P 25.0 kg ha^?1, N 106.6 kg ha^?1, and K 245.5 kg ha^?1 to seasonal crops.     

Pathogen reduction in minimally managed composting of bovine manure

Spread of manure pathogens is of considerable concern due to use of manure for land application. In this study, the effects of four static pile treatment options for bovine manure on die-off of a generic Escherichia coli, E. coli O157:H7 surrogate, Salmonella Senftenberg, Salm. Typhimurium, and Listeria monocytogenes were evaluated. Bovine manure spiked with these bacteria were placed in cassettes at the top, middle, and bottom sections of four static pile treatments that reflect minimal changes in pile construction with and without straw. Temperatures were monitored continuously during the 28 day self-heating period. E. coli and salmonellae were reduced from 8 to 9 log₁₀ CFU g^?1 to undetectable levels (<1.77 log₁₀ MPN g^?1) at 25–30 cm depths within 7 days in all pile sections except for the manure-only pile in which 3–4 logs of reduction were obtained. No L. monocytogenes initially present at 6.62 log₁₀ CFU g^?1 were recovered from straw-amended piles after 14 days, in contrast with manure-only treatment in which this pathogen was recovered even at 28 days. Decline of target bacterial populations corresponded to exposure to temperatures above 45 °C for more than 3 days and amendments of manure with straw to increase thermophilic zones. Use of straw to increase aeration, self-heating capacity, and heat retention in manure piles provides producers a minimal management option for composting that enhances pathogen die-off and thereby reduces risk of environmental spread when manure is applied to land.     

Effect of different tannery sludge compost amendment rates on growth,biomass accumulation and yield responses of Capsicum plants

Composting has been recognized as one of the most cost effective and environmentally sound alternatives for organic wastes recycling from long and composted wastes have a potential to substitute inorganic fertilizers. We investigated the potential of composted tannery sludge for ornamental purposes and to examine the effects of two different composts and concentrations on ornamental Capsicum growth. The two composts were produced with tannery sludge and the composition of each compost was: compost₁ of tannery sludge (C₁TS) – tannery sludge + sugarcane straw and cattle manure mixed in the ratio 1:3:1 (v:v:v); compost₂ of tannery sludge (C₂TS) – tannery sludge + “carnauba” straw and cattle manure in the ratio 1:3:1 (v:v:v). Each compost was amended with soil at rates (% v:v) of 0%, 25%, 50%, 75% and 100% (designation hereafter as T₁–T₅, respectively). The number of leaves and fruits were counted, and the stem length was also measured. Chlorophyll content was recorded on three leaves of each harvested plant prior to harvest. Number of leaves and fruits, stem length, dry weight of shoot and roots did not vary significantly between the plants grown in two tannery composts. All the treatments with composted tannery sludge application (T₂–T₅) significantly increased the number of leaves and fruits, stem length and chlorophyll content compared with the control (T₁). The chlorophyll content was higher in plants growing in the C₁TS compared to C₂TS. The results of the present study further suggest that Capsicum may be a good option to be grown on composted tannery amended soil.     

Sulfide emissions from different areas of a municipal solid waste landfill in China

Degradation of municipal solid waste in landfills generates sulfide compounds, which are considered one of the main sources of odor emissions. Field sampling was conducted at surfaces of operating, inoperative, and soil-covered areas of a landfill site in northern China to characterize the sulfide compounds. The results showed that dimethyl disulfide dominated the sulfide compounds, accounting for up to 73.6% of the total detected sulfide. With the biggest odor concentration of 365, diethyl sulfide was the most significant sulfide compound. The estimated sulfide emission rates at surfaces of operating and soil-covered areas were similar, and the emission rate of dimethyl disulfide at Surface of Operating Area was up to 345.9 μg/m³ h. Dimethyl disulfide could be released from the fresh waste, and its normalized concentration at 0.2 m beneath operating surface was 10.4 times that at 0.4 m.