Low Organic Waste Research Articles

Itaconic acid: microbial production using organic wastes as cost-effective substrates

Abstract Itaconic acid is one of industrially important organic acid having wide application in environmental protection, food and textile industries. Microorganisms mainly fungi have vast potential to be exploited for itaconic acid production. But low yield and higher cost of production are major drawback creating a settle back for industrial production. This problem can be solved by using low cost organic waste as substrate. This review summarizes recent research on production of itaconic acid using organic wastes, microorganisms involved, extraction, application and problem faced during utilization of agro-industrial wastes.

Organic waste derived biodiesel supply chain network: Deterministic multi-period planning model

In this study, a multi-period model of an organic waste-to-biodiesel phased supply chain network is developed to strategically consider variations in the biodiesel demand and the organic waste usage over a long-term planning interval. The proposed model can facilitate planning to determine the biorefinery location and the amount of biodiesel to produce, transport, or utilize to reduce the total cost of the organic waste-to-biodiesel supply chain network design while meeting the biodiesel demand during each period of the planning interval. The features and capabilities of the model are validated by application of a future organic waste-to-biodiesel supply chain network design in South Korea. The optimization results illustrate that the average total annual cost of the organic waste of biodiesel based on the multi-period model will be $US 4.2 billion per year during the period 2020–2030. The minimum selling prices for the optimal network design were determined ranged from $US 3.154–3.156/gallon of biodiesel containing 3% butanol derived from organic waste combined with diesel. A small portion (4.9–6.6%) of the total biodiesel demand was produced from organic waste because of low organic waste availability in the existing anaerobic digestion facilities, leading to increasing the outsourcing costs of butanol. The proposed approach will facilitate the strategic development of a sustainable supply chain network for organic waste recycling for material and energy valorization.

Trace gas composition in landfill gas at Danish landfills receiving low-organic waste

In 1997, the landfilling of biodegradable waste was banned in Denmark, and currently Danish landfills receive mostly non-combustible waste with a low-organic content. This study aimed to investigate trace gas composition in landfill gas (LFG) at modern Danish landfills. Landfill gas samples were taken from waste cells containing shredder, mixed and aged waste from four Danish landfills. The highest trace gas concentrations were found in shredder waste cells (average concentration of 103 mg m−3), which were comparable with conventional municipal solid waste landfills receiving organic waste. Aliphatic hydrocarbons and aromatics were dominant in the shredder waste cells, most likely released through direct volatilisation from disposed waste products. Abundant oxygenated compounds were found in the shredder waste cell in one of the landfills, thereby indicating a higher level of organic fraction biodegradation. Benzene, toluene, ethylbenzene and xylenes (BTEXs) were measured in high concentrations in all shredder waste cells, contributing to more than 75% of total aromatics. Considerably lower concentrations of trace gases were measured in the mixed and aged waste cells, which were dominated by hydrogen sulphide and several aliphatic hydrocarbons. A constant concentration ratio was established between aliphatic hydrocarbons together with aromatics and methane in shredder waste cells, which was then used in an LFG generation model to estimate trace gas production. The production rates of BTEXs from two landfills were estimated at 272 and 73 kg yr−1 in 2020, which were not considered to pose a significant risk to the environment or to human health.

Optimization of Protein Extraction from the Low Organic Residual Municipal Sludge Waste

In this study, municipal sludge waste was used for protein extraction. Two pretreatment ways such as acid and alkaline hydrolysis were compared and the alkaline hydrolysis method was selected as the better way for protein extraction from the residual sludge. In order to obtain the optimal condition for protein extraction, the factors such as NaOH concentration, NaOH solution volume and pretreatment period were selected and optimized by response surface methodology, and the optimal condition for protein extraction was obtained: NaOH concentration was 3.85 mol/l , 24.0 g wet municipal sludge waste was added in 1 L of water, and the pretreatment period was of 12.16 h at 50 °C. Under the optimal extraction condition, the protein extraction yield could reach 5923±107 μg/g sludge, which were 2.07 folds than the initial production pretreated by NaOH.

Insights into organic waste management practices followed by dairy farmers of Ludhiana District, Punjab: Policy challenges and solutions.

The study was conducted in Ludhiana District of Punjab (India) to understand the organic waste management practices followed by dairy farmers of the area. To investigate the practices pertaining to organic waste management, an ex-post facto research design was used and a total of 80 dairy farmers were selected randomly for the study, grouped as small and large dairy farmers. Results revealed that the majority of the farmers were using paddy straw as animal bedding followed by in situ burning. As far as paddy stubbles were concerned, most of the farmers were mulching them followed by in situ burning. All farmers were found to be using wheat straw as livestock feed and mulching wheat stubbles. For household waste, the majority of the farmers were found to be feeding kitchen waste to their livestock, preparing farmyard manure from garden waste and paper waste. For dairy waste management, all the farmers were preparing farmyard manure from dung and discarding livestock urine in drains. A little more than half of the farmers were producing biogas from the dairy waste. The majority of the dairy farmers of the research area were found to have low organic waste utilization scores. Relational analysis was carried out and social participation and knowledge level were found to be highly significant (p < 0.01) with a positive effect on the organic waste utilization score. Therefore, the study was concluded with the impression that the knowledge level of the farmers needs to be enhanced for better and effective utilization of organic waste.

Physicochemical Parameters and Heavy Metal Concentration in Water at the Mokesh Beel of Bangladesh

The study investigated physicochemical parameters and heavy metal concentrations in water of the Mokesh beel during January to June 2016. Samples were collected from 3 different locations and analyzed in the laboratory of the Department of Environmental Science and Resource Management, MBSTU, Tangail and BINA, Mymensingh. Results showed that EC and TDS were varied from 645-688μS/cm and 541-586mg/l, respectively indicated high ionic concentration, whereas DO of all stations ranged from 4.1-5.5mg/l represents low organic waste, and pH (7.25-7.55) of all stations showed alkaline nature. In case of heavy metal concentration Pb, Cd, Cu, Zn and Cr were within the standard level. The result concludes that the water can be used for different purposes but heavy metals can be accumulated in fish flesh, consequently affect the human health. To maintain the water quality and conserve the aquatic life, proper measures should be taken to prevent pollutants intrusion into the beel.&#x0D; J. Environ. Sci. &amp; Natural Resources, 11(1-2): 1-8 2018

Bioinspired Synthesis of Carbon Dots/g-C3N4 Nanocomposites for Photocatalytic Application

This study reports a fast and green preparative strategy to synthesize water soluble and fluorescent carbon quantum dots (CQDs) through hydrothermal method by using low cost organic waste of human fingernails as the carbon precursor for the first time. The coupling of CQD with pure carbon nitride (g-C3N4) was further explored to enhance the latter’s performance in photocatalysis of 2,4-dicholorophenol (2,4-DCP), a toxic and recalcitrant compound mostly released from industrial effluent. Such coupling overcame the weakness of pure g-C3N4 in photocatalysis process by broadening its visible light absorption and promoting the charge separation. As a result, the removal rate of CQD/ g-C3N4(10) was up to 71.53%, which was approximately 1.5 times higher than that of pure g-C3N4 under sunlight irradiation. The morphological structure, optical properties and chemical compositions of CQDs/g-C3N4 composites were characterized using various spectroscopic techniques including field emission scanning electron microscopy (FESEM), Energy Dispersive X-Ray (EDX) and Ultraviolet-visible diffuse reflectance spectra (UV-DRS).

PCB in the environment: bio-based processes for soil decontamination and management of waste from the industrial production of Pleurotus ostreatus

Polychlorinated biphenyls (PCBs) are hazardous soil contaminants for which a bio-based technology for their recovery is essential. The objective of this study was to validate the exploitation of spent mushroom substrate (SMS), a low or null cost organic waste derived from the industrial production of P. ostreatus, as bulking agent in a dynamic biopile pilot plant. The SMS shows potential oxidative capacity towards recalcitrant compounds. The aim was consistent with the design of a process of oxidation of highly chlorinated PCBs, which is independent from their reductive dehalogenation. Feasibility was verified at a mesocosm scale and validated at pilot scale in a dynamic biopile pilot plant treating ten tons of a historically contaminated soil (9.28±0.08mg PCB/kg soil dry weight). Mixing of the SMS with the soil was required for the depletion of the contaminants. At the pilot scale, after eight months of incubation, 94.1% depletion was recorded. A positive correlation between Actinobacteria and Firmicutes active metabolism, soil laccase activity and PCB removal was observed. The SMS was found to be exploitable as a versatile low cost organic substrate capable of activating processes for the oxidation of highly chlorinated PCBs. Moreover, its exploitation as bulking agent in biopiles is a valuable management strategy for the re-utilisation of an organic waste deriving from the industrial cultivation of edible mushrooms.

Ultrasound-assisted extraction combined with reverse phase-dispersive liquid-liquid micro extraction as a new approach for preconcentration and spectrophotometric determination of total phenol in marine sediments of Chabahar Bay

In this study, Reverse phase dispersive liquid–liquid micro extraction (RP-DLLME) technique have been successfully developed to preconcentrate trace amount of phenol from sediment samples as a prior step to its derivatization with 4-aminoantipyrine and enhanced determination by UV–Vis spectrophotometry after primary ultrasonic extraction. In this procedure, 50μL 0.7M NaOH solution was chosen as extraction solvent and other factors including pH, extraction time, concentration of 4-aminoantipyrine, type and volume of dispersive solvents were optimized. Under selected conditions, the limit of detection, the linearity range, relative standard deviation and enrichment factor of method were obtained 15μg·kg−1, 50–1800μg·kg−1, 4.8% (n=10) and 33, respectively. Finally, using the high sensitivity, low organic solvent consumption and waste generation method, total phenol content in marine sediments from several locations in Chabahar Bay (southeast Iran) was estimated at 55.8–73.2μg·kg−1.

Evaluation and application of site-specific data to revise the first-order decay model for estimating landfill gas generation and emissions at Danish landfills

Methane (CH4) generated from low-organic waste degradation at four Danish landfills was estimated by three first-order decay (FOD) landfill gas (LFG) generation models (LandGEM, IPCC, and Afvalzorg). Actual waste data from Danish landfills were applied to fit model (IPCC and Afvalzorg) required categories. In general, the single-phase model, LandGEM, significantly overestimated CH4 generation, because it applied too high default values for key parameters to handle low-organic waste scenarios. The key parameters were biochemical CH4 potential (BMP) and CH4 generation rate constant (k-value). In comparison to the IPCC model, the Afvalzorg model was more suitable for estimating CH4 generation at Danish landfills, because it defined more proper waste categories rather than traditional municipal solid waste (MSW) fractions. Moreover, the Afvalzorg model could better show the influence of not only the total disposed waste amount, but also various waste categories. By using laboratory-determined BMPs and k-values for shredder, sludge, mixed bulky waste, and street-cleaning waste, the Afvalzorg model was revised. The revised model estimated smaller cumulative CH4 generation results at the four Danish landfills (from the start of disposal until 2020 and until 2100). Through a CH4 mass balance approach, fugitive CH4 emissions from whole sites and a specific cell for shredder waste were aggregated based on the revised Afvalzorg model outcomes. Aggregated results were in good agreement with field measurements, indicating that the revised Afvalzorg model could provide practical and accurate estimation for Danish LFG emissions. This study is valuable for both researchers and engineers aiming to predict, control, and mitigate fugitive CH4 emissions from landfills receiving low-organic waste.Implications: Landfill operators use the first-order decay (FOD) models to estimate methane (CH4) generation. A single-phase model (LandGEM) and a traditional model (IPCC) could result in overestimation when handling a low-organic waste scenario. Site-specific data were important and capable of calibrating key parameter values in FOD models. The comparison study of the revised Afvalzorg model outcomes and field measurements at four Danish landfills provided a guideline for revising the Pollutants Release and Transfer Registers (PRTR) model, as well as indicating noteworthy waste fractions that could emit CH4 at modern landfills.

Evaluating the methane generation rate constant (k value) of low-organic waste at Danish landfills

The methane (CH4) generation rate constant (k value, yr−1) is an essential parameter when using first-order decay (FOD) landfill gas (LFG) generation models to estimate CH4 generation from landfills. Four categories of waste (street cleansing, mixed bulky, shredder, and sludge waste) with a low-organic content, as well as temporarily stored combustible waste, were sampled from four Danish landfills. Anaerobic degradation experiments were set up in duplicate for all waste samples and incubated for 405days, while the cumulative CH4 generation was continuously monitored. Applying FOD equations to the experimental results, half-life time values (t½, yr) and k values of various waste categories were determined. In general, similar waste categories obtained from different Danish landfills showed similar results. Sludge waste had the highest k values, which were in the range 0.156–0.189yr−1. The combustible and street cleansing waste showed k values of 0.023–0.027yr−1 and 0.073–0.083yr−1, respectively. The lowest k values were obtained for mixed bulky and shredder wastes ranging from 0.013 to 0.017yr−1. Most low-organic waste samples showed lower k values in comparison to the default numeric values in current FOD models (e.g., IPCC, LandGEM, and Afvalzorg). Compared with the k values reported in the literature, this research determined low-organic waste for the first time via reliable large-scale and long-term experiments. The degradation parameters provided in this study are valuable when using FOD LFG generation models to estimate CH4 generation from modern landfills that receive only low-organic waste.

Evaluating the biochemical methane potential (BMP) of low-organic waste at Danish landfills

The biochemical methane potential (BMP) is an essential parameter when using first order decay (FOD) landfill gas (LFG) generation models to estimate methane (CH4) generation from landfills. Different categories of waste (mixed, shredder and sludge waste) with a low-organic content and temporarily stored combustible waste were sampled from four Danish landfills. The waste was characterized in terms of physical characteristics (TS, VS, TC and TOC) and the BMP was analyzed in batch tests. The experiment was set up in triplicate, including blank and control tests. Waste samples were incubated at 55°C for more than 60days, with continuous monitoring of the cumulative CH4 generation. Results showed that samples of mixed waste and shredder waste had similar BMP results, which was in the range of 5.4–9.1kgCH4/ton waste (wet weight) on average. As a calculated consequence, their degradable organic carbon content (DOCC) was in the range of 0.44–0.70% of total weight (wet waste). Numeric values of both parameters were much lower than values of traditional municipal solid waste (MSW), as well as default numeric values in current FOD models. The sludge waste and temporarily stored combustible waste showed BMP values of 51.8–69.6 and 106.6–117.3kgCH4/ton waste on average, respectively, and DOCC values of 3.84–5.12% and 7.96–8.74% of total weight. The same category of waste from different Danish landfills did not show significant variation. This research studied the BMP of Danish low-organic waste for the first time, which is important and valuable for using current FOD LFG generation models to estimate realistic CH4 emissions from modern landfills receiving low-organic waste.

Development and comparison of two dispersive liquid–liquid microextraction techniques coupled to high performance liquid chromatography for the rapid analysis of bisphenol A in edible oils

In this study, two novel sample extraction methods for the analysis of bisphenol A (BPA) in edible oils were developed by using liquid–liquid extraction followed by a dispersive liquid–liquid microextraction (LLE-DLLME) and reversed-phase dispersive liquid–liquid microextraction (RP-DLLME). RP-DLLME showed a superior characteristic over LLE-DLLME and other previously reported procedures because of its easy operation, short extraction time, high sensitivity, low organic solvent consumption and waste generation. The optimized extraction conditions of RP-DLLME for 1.0g of edible oil diluted in 4mL of n-hexane were: extractant, 100μL 0.2M sodium hydroxide solution (80% methanol, v/v); extraction time, 1min; centrifugation, 3min. The determination of BPA was carried out by high performance liquid chromatography coupled with a DAD detector. The method offered excellent linearity over a range of 0.010–0.5μgg−1 with a correlation coefficient of r>0.997. Intra-day and inter-day repeatability values expressed as relative standard deviation were 1.9% and 5.9%, respectively. The quantitation limit and detection limit were 6.3 and 2.5ngg−1. The target analyte was detected in 5 out of 16 edible oil samples. The recovery rates in real samples ranged from 89.5 to 99.7%.

Environmental assessment of low-organic waste landfill scenarios by means of life-cycle assessment modelling (EASEWASTE)

The environmental performance of two low-organic waste landfill scenarios ('low-organic-energy' and 'low-organic-flare') was developed and compared with two household waste landfill scenarios ('household-energy' and 'household-flare') by means of LCA-modelling. The LCA-modelling was made for 1 tonne of wet waste landfilled and the environmental aspects were evaluated for a 100-year period after disposal. The data utilized in the LCA-calculations to model the first 10-20 years of landfilling of the two low-organic waste scenarios make extensive use of site-specific data from the Nauerna Landfill (The Netherlands), but average data from other comparable, existing landfills were used too. As data from full-scale landfills do not cover more than 30-40 years of landfilling, data from laboratory simulations and accelerated tests of limited scale were also utilized. The life-cycle impact assessments show that the low-organic waste scenarios achieved better environmental performance than the household waste scenarios with regard to both ordinary and toxicity-related environmental impact categories. This indicates that the reduction of organic matter accepted at landfills (as prescribed by the European Union Landfill Directive: Council Directive 1999/31/EC, EU, Brussels, 1999) can be a successful approach to decrease the environmental loads in several impact categories in comparison with landfilling of waste with significant organic content. However, when utilization of landfill gas is accounted for in the life-cycle impact assessment calculation, the small gas generation in low-organic waste landfills reduced the actual potential for energy generation and therefore the environmental savings obtained were reduced proportionally. Groundwater pollution from input of leachate was also evaluated and the WHO (Guidelines for Drinking-water Quality; WHO, Geneva, 2006) guideline for drinking water quality was assumed as reference. The results show that low-organic waste landfills pose a smaller risk of groundwater contamination, but the impact potentials estimated still remain a lot higher than estimated in other categories.

Evaluating the use of electrical resistivity imaging technique for improving CH 4 and CO 2 emission rate estimations in landfills

In order to improve the estimation of surface gas emissions in landfill, we evaluated a combination of geophysical and greenhouse gas measurement methodologies. Based on fifteen 2D electrical resistivity tomographies (ERTs), longitudinal cross section images of the buried waste layers were developed, identifying place and cross section size of organic waste (OW), organic waste saturated in leachates (SOW), low organic and non-organic waste. CH 4 and CO 2 emission measurements were then conducted using the static chamber technique at 5 surface points along two tomographies: (a) across a high-emitting area, ERT#2, where different amounts of relatively fresh OW and SOW were detected, and (b) across the oldest (at least eight years) cell in the landfill, ERT#6, with significant amounts of OW. Where the highest emission rates were recorded, they were strongly affected by the thickness of the OW and SOW fraction underneath each gas sampling point. The main reason for lower than expected values was the age of the layered buried waste. Lower than predicted emissions were also attributed to soil condition, which was the case at sampling points with surface ponding, i.e. surface accumulation of leachate (or precipitated water).