Anthropogenic emissions from coal-water slurry combustion: Influence of component composition and registration methods.

The flue gas composition is often measured using a combination of techniques that differ in terms of both physical operation principle and type of output. Gas analyzers, FTIR spectrometers, and mass spectrometers are the most popular tools used for this purpose. In this research, we study the composition of the flue gas from the combustion of fuel slurries and dry composite fuels based on industrial and agricultural waste. It has been established that the use of slurry fuels makes the anthropogenic emissions 2-4 times lower than from the combustion of coal slime. For example, the CO2 emissions from the combustion of dry coal slime were 2.5-3.7 times higher than from the combustion of slurry fuels. In addition, the combustion of slurry fuels made it possible to cut down the nitrogen oxide emissions by 1.3-1.5 times and sulfur oxide emissions by 1.3-2.7 times. A comparison of the results obtained using different measurement techniques has shown that differences between the CO and CO2 content in the combustion products measured by a gas analyzer and an FTIR spectrometer did not exceed 20%. The use of FTIR spectroscopy provided new knowledge on the concentrations of hydrocarbons from the combustion of fuels based on promising industrial wastes.

Stochastic modeling and meta-heuristic multivariate optimization of bioprocess conditions for co-valorization of feather and waste frying oil toward prodigiosin production.

Serratia marcescens strain UCCM 00009 produced a mixture of gelatinase and keratinase to facilitate feather degradation but concomitant production of prodigiosin could make waste feather valorization biotechnologically more attractive. This article describes prodigiosin fermentation through co-valorization of waste feather and waste frying peanut oil by S. marcescens UCCM 00009 for anticancer, antioxidant, and esthetic applications. The stochastic conditions for waste feather degradation (WFD), modeled by multi-objective particle swarm-embedded-neural network optimization (ANN-PSO), revealed a gelatinase/keratinase ratio of 1.71 for optimal prodigiosin production and WFD. Luedeking-Piret kinetics revealed a non-exclusive, non-growth-associated prodigiosin yield of 9.66 g/L from the degradation of 88.55% waste feather within 96 h. The polyethylene glycol (PEG) 6000/Na+ citrate aqueous two-phase system-purified serratiopeptidase demonstrated gelatinolytic and keratinolytic activities that were stable for 240 h at 55 °C and pH 9.0. In vitro evaluations revealed that the prodigiosin inhibited methicillin-resistant Staphylococcus aureus at IC50 of 4.95 µg/mL, the plant-pathogen, Sclerotinia sclerotiorum, at IC50 of 2.58 µg/mL, breast carcinoma at IC50 of 0.60 µg/mL and 2,2-diphenyl-1-picryl-hydrazyl hydrate (DPPH) free-radical at IC50 of 96.63 µg/mL). The pigment also demonstrated commendable textile dyeing potential of fiber and cotton fabrics. The technology promises cost-effective prodigiosin development through sustainable waste feather-waste frying oil co-management.

Baseline study to determine the implementation area of an oily waste management system for artisanal fishing vessels.

This work seeks to perform a baseline study to determine the implementation area for a management system of oily waste generated by artisanal fishing boats within the Peruvian context. This explanatory study, conducted based on quantitative and cross-sectional considerations, includes a regulatory review; content analysis of polynuclear aromatic hydrocarbons (PAH) and total petroleum hydrocarbons (TPH) both in seawater and sediments; and metal assessment in sediments and waste oil, with the corresponding result correlations. In this study, the results reveal that while regulations are adequate, their implementation is not evident. In addition, no evidence of contamination by PAH and TPH was found. However, traces of metal contamination were found in sediments, and, after being correlated with the metal values from waste oil, a Spearman's Rho correlation coefficient of 0.619480 was reported. Hence, we can conclude that the regulations to prevent marine pollution from oily waste contained in the International Convention for the Prevention of Pollution from Ships MARPOL agreement have been accepted and approved for implementation. In fact, they can even be applied to different activities that fall out of the scope of the agreement. Finally, the baseline study reveals oily waste generation indicators, as well as a correlation between waste oil metals and marine sediment metals that merits the implementation of an oily waste management system within the study area.

STARx Hottpad for smoldering treatment of waste oil sludge: Proof of concept and sensitivity to key design parameters.

Growing stockpiles of waste oil sludge (WOS) are an outstanding problem worldwide. Self-sustaining Treatment for Active Remediation applied ex situ (STARx) is a treatment technology based on smoldering combustion. Pilot-scale experiments for the STARx Hottpad prove this new concept for the mobile treatment of WOS mixed intentionally with sand or contaminated soil. The experiments also allowed for the calibration and validation of a smoldering propagation numerical model. The model was used to systematically explore the sensitivity of Hottpad performance to system design, operational parameters, and environmental factors. Pilot-scale (~1.5 m width) simulations investigated sensitivity to injected air flux, WOS saturation, heterogeneity of intrinsic permeability, and heterogeneity of WOS saturation. Results reveal that Hottpad design is predicted to be successful for WOS treatment across a wide range of scenarios. The operator can control the rate of WOS destruction and extent of treatment by increasing the air flux injected into the bed. The potential for smoldering channeling to develop was demonstrated for the first time. Under certain conditions, such as WOS saturations of 80%, high heterogeneity of WOS saturations, or moderate to high heterogeneity of soil permeability, smoldering channeling was predicted to accelerate to the point that remedial performance was degraded. Field-scale simulations (~10 m width) predicted successful treatment, with WOS destruction rates an order of magnitude higher than the pilot-scale and treatment times increasing only linearly with bed height. This work is a key step toward the design and effective operation of field STARx Hottpad systems for eliminating WOS.

System analysis of waste oil management in Finland.

Waste oil management systems include processes such as generation, collection, recycling, and disposal and result in various environmental, economic, social, and regulatory impacts which complicate waste management analysis. In this paper, the waste oil management system in Finland is analysed using the systems thinking approach to identify the main system components and to describe the interactions between them. The results of analysing the Finnish system increase the understanding of the main factors affecting the performance of waste oil management. The outcome of this analysis can be adapted for the examination of similar systems. The waste oil management system analysis shows an increase in the performance: the waste oil collection rate within the official collection system has increased more than 30% during the last 6 years. The environmental performance of the treatment and recovery system have increased, taking into account the increase of the material recovery rate, more than 70% during the last 6 years.

Study on the production of Sophorolipid by Starmerella bombicola yeast using fried waste oil fermentation.

Sophorolipids (SLs) are surface active compounds that have excellent surface-lowering properties. SLs were produced by Starmerella bombicola (CGMCC1576) yeast with sunflower seed oil, fried waste oil, cooked tung oil and raw tung oil used as hydrophobic carbon sources. The results showed that the strain could use sunflower seed oil and fried waste oil as hydrophobic carbon sources to produce SLs, and the yields were 44.52 and 39.09 gl-1. It could not be used as cooked tung oil and raw tung oil. The analysis by high-performance liquid chromatography/high resolution mass spectrometry (HPLC-MS/MS) showed that the main composition and structure of SLs produced by fermentation using fried waste oil were similar to that of sunflower seed oil as hydrophobic carbon source. The yield of SLs was the highest when the fried waste oil was used as hydrophobic carbon source, glucose (8%), waste oil (6%) and yeast (0.3%). When fried waste oil was used as a hydrophobic carbon source in a parallel 4-strand fermentation tank (FT), the combination with the largest yield and the most cost saving was that 3% of fried waste oil was added into the initial medium, and another 3% was again added after 72 h of fermentation. The total yield of SLs was 121.28 gl-1, and the yield of lactone SLs was 48.07 gl-1.

Preparation of a capsaicinoids broad spectrum antibody and its application in non-enzyme immunoassay based on DMSNs@PDA@Pt.

Capsaicinoids (CPCs) is a special ingredient with pungent smell in condiments, which can also be used as an exogenetic marker for kitchen waste oil. Development of immunoassay for CPCs remains a challenging due to relatively difficult preparation of the broad-spectrum antibody (Ab). In this work, a broad-spectrum polyclonal antibody (pAb) which can simultaneously recognize capsaicin (CPC), dihydrocapsaicin (DCPC), nordihydrocapsaicin (NDCPC), and N-vanillylnonanamide (N-V) is produced, and a non-enzyme immunoassay (NISA) based on this Ab, dendritic mesoporous silica nanomaterials (DMSNs), polydopamine (PDA), and high catalytic efficiency of Pt nanoparticles to prepare signal probe (DMSNs@PDA@Pt) is established. Here, the limit of detection (LOD) of NISA for CPC is as low as 0.04 µg L-1. It is worth mentioning that the LOD of the proposed NISA is at least 23 times lower than that of traditional enzyme-linked immunosorbent assay (ELISA) based on horseradish peroxidase (HRP). Moreover, the proposed NISA is applied to detect CPCs in edible oil samples, the result has good consistency with that of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The proposed NISA based on DMSN@PDA@Pt and broad-spectrum Ab is an ideal tool for highly effective screening CPCs for kitchen waste oil abuse surveillance.

ZSM-5@ceramic foam composite catalyst derived from spent bleaching clay for continuous pyrolysis of waste oil to produce monocyclic aromatic hydrocarbons.

Spent bleaching clay, a solid waste generated during the refining process of vegetable oils, lacks an efficient treatment solution. In this study, spent bleaching clay was innovatively employed to fabricate ceramic foams. The thermal stability analysis, microstructure, and crystal phase composition of the ceramic foams were characterized by TG-DSC, SEM, and XRD. An investigation into the influence of Al2O3 content on the ceramic foams was conducted. Results showed that, as the Al2O3 content increased from 15 wt% to 30 wt%, there was a noticeable decrease in bulk density and linear shrinkage, accompanied by an increase in compressive strength. Additionally, the ceramic foams were used as catalyst supports, to synthesize ZSM-5@ceramic foam composite catalysts for pyrolysis of waste oil. The open pores of the ZSCF catalyst not only reduced diffusion path length but also facilitated the exposure of more acid sites, thereby increasing the utilization efficiency of ZSM-5 zeolite. This, in turn, engendered a significant enhancement in monocyclic aromatic hydrocarbons content from 39.15 % (ZSM-5 powder catalyst) to 78.96 %. Besides, a larger support pore size and a thicker ZSM-5 zeolite coating layer led to an increase in monocyclic aromatic hydrocarbons content. As the time on stream was extended to 56 min, the monocyclic aromatic hydrocarbon content obtained with the composite catalyst remained 12.41 % higher than that of the ZSM-5 powder catalyst. These findings validate the potential of the composite catalyst. In essence, this study advances the utilization of spent bleaching clay and introduces a novel concept for ceramic foam fabrication. Furthermore, it contributes to the scaling up of catalytic pyrolysis technology.

Conversion of Waste Oil from Oil Refinery into Emulsion Liquid Membrane for Removal of Phenol: Stability Evaluation, Modeling and Optimization.

The waste oil emulsion liquid membrane produced by waste oil from oil refineries (WELM) is used to separate the phenol in purified water from the sour water stripper in oil refinery facilities, and the stability of WELM was studied. It is verified that waste refinery oil can be produced into emulsion liquid membrane with good stability and high removal rate for the first time. The WELM stability models were established by response surface methodology (RSM) and artificial neural network (ANN), respectively. The principle and mechanism of various parameters, as well as the interaction effects on the stability of WELM, are proposed. The effects of parameters, including the ratio of Span-80, liquid paraffin, the ratio of internal and oil, and the rotational speed of the homogenizer, were investigated. Under the optimal operating parameters, the WELM had a demulsification percentage of just 0.481%, and the prediction results of RSM and ANN were 0.536% and 0.545%, respectively. Both models demonstrate good predictability. The WELM stability model has a high application value in the treatment of phenol-containing wastewater in the oil refining industry, and provides a green method of resource recovery.

Study the fuel characteristics of ethanol and waste engine oil pyrolytic oil blends.

This study shows the application of pyrolytic oil derived from waste engine oil (WEOPO) as an alternative fuel by blending with ethanol. For this, the effect of blending of ethanol at 5 %, 10 %, 15 %, 20 %, 25 %, and 30 % on the compositions and fuel properties were analyzed. The utmost blending was established based on the higher heating value. The pyrolytic oil used for this study was produced at 550 °C which was the optimum pyrolytic temperature. A comparison study of the blended oil was performed with commercially available gasoline to observe the similarities in their fuel properties and composition. The study confirmed that ethanol can be blended with WEOPO at 20 % by volume to obtain a fuel of a higher heating value of about 44.24 MJ/kg that can be used as fuel. Since WEOPO contains 65.80 % of C4-C12 (gasoline range), hydrocarbon compounds and the rest 31.48 % C11-C15, 11.84 % C15-C19, and 6.94 % > C19 compounds, it can be used as a future fuel.

A promising nanostructured bimetallic catalyst for the production of second-generation biodiesel: reuse and stability study.

The stability and reusability of a promising bimetallic mesoporous catalyst (5Na/20Ce/SBA-15) to produce first- and second-generation biodiesel was studied. Soybean oil, waste frying oil, and Jatropha hieronymi oil were used as lipid raw materials. Under optimized reaction conditions (10 wt % of catalyst, methanol to oil molar ratio of 40 : 1, 60 °C, and vigorous magnetic stirring), the minimum FAME content required by the EN 14214 standard was achieved in 3 h with soybean oil and waste frying oil. Three alternatives were considered concerning the reuse of the catalyst (without and with regeneration), concluding that washing followed by calcination between each run is suitable for the material to recover its activity. FAME contents over 87 wt % were obtained in five cycles when using waste frying oil. Key quality properties of the produced biofuel were evaluated and found to comply with international standards for its commercialization as automotive diesel fuel without further treatment.

Experimental Investigation and Performance Optimization during Machining of Hastelloy C-276 Using Green Lubricants.

Smart manufacturing is the demand of industry 4.0, in which the mass production of difficult-to-cut materials is of great concern to fulfil the goal of sustainable machining. Presently, the machining of superalloy is of upmost interest because of its wide application. However, the limited data on the turning of Hastelloy C-276 highlights its challenges during processing. Hence, the machining performance of superalloy considering surface quality, thermal aspects and chip reduction coefficient was examined with minimum quantity lubrication of several oils to address the sustainable development goal (SDG-12). The output responses were optimized through response surface methodology along with analysis of variance. The research exhibited that the output responses were dominated by cutting speed and feed rate having a percentage benefaction of 24.26% and 60%, respectively, whilst the depth of cut and lubricant type have an influence of 10-12%. No major difference in temperature range was reported during the different lubrication conditions. However, a substantial variation in surface roughness and the chip reduction coefficient was revealed. The percentage error evaluated in surface roughness, temperature and chip reduction coefficient was less than 5%, along with an overall desirability of 0.88, describing the usefulness of the model used. The SEM micrograph indicated a loss of coating, nose and flank wear during all lubrication conditions. Lastly, incorporating a circular economy has reduced the economic, ecological and environmental burden.

Biosynthesis of polyhydroxyalkanoate from food waste oil by Pseudomonas alcaligenes with simultaneous energy recovery from fermentation wastewater.

Bioconversion of food waste oil (FWO) into biodegradable plastic is a promising method for converting waste into high-value products. In this study, a strain (Pseudomonas sp. H3) was isolated for polyhydroxyalkanoate (PHA) synthesis from FWO. After 72 h of cultivation with 20 g/L of FWO, the high cell dry weight (CDW) of 3.6 g/L, PHA yield of 2.4 g/L, and PHA content of 65 wt% were obtained under the optimal temperature (25 °C) and inoculum amount (6% (v/v)). Fed-batch fermentation was conducted in a 5 L bioreactor with a maximum CDW of 16 g/L, PHA content of 54 wt%, and PHA productivity of 0.23 g/(L·h) after 36 h. The PHA had a molecular weight of 54 782 Da and a low polydispersity index of 1.41 with glass transition, melting, and degradation temperatures of -20 °C, 34 °C, and 210 °C, respectively. To further utilize the wastewater after PHA production, anaerobic digestion was employed for CH4 production, and the CH4 yield was 284 mL/g volatile solids. Microbial community analysis showed that the abundance of acetate-oxidizing bacteria and Methanobacterium significantly increased during anaerobic digestion. This study describes a new strain for the economical synthesis of biodegradable plastics and presents a novel framework for fully utilizing FWO with the production of PHA and CH4.

Metabolic Checkpoint Aldehyde Dehydrogenases Are Important for Diverting ß-Oxidation into 1-Butanol Biosynthesis from Kitchen Waste Oil in Pseudomonas aeruginosa.

1-Butanol (1-BD) is a promising fuel additive which can be biosynthesized via reversed ß-oxidation pathway in bacteria. However, heterologous reversed ß-oxidation pathway is a carbon chain prolongation process with several genes overexpressed in most of bacterial hosts, leading to low titer of 1-BD and high cost for production. Here we displayed a forward ß-oxidation pathway for 1-BD production in a kitchen waste oil (KWO) degrading Pseudomonas aeruginosa PA-3, and we proved that aldehyde dehydrogenase (ALDH) is a checkpoint for diverting metabolic flux into 1-BD biosynthesis. With nitrogen source supplied, titer of 1-BD was increased accompanied with 12 ALDH coding genes transcriptionally promoted to different degrees. At the same time, binding energies of these ALDHs with different length of acyl-CoAs in ß-oxidation were calculated to identify their specificities. Based on the above information, ALDH deletions were conducted. We certified that deletion of ALDH8 and ALDH9 led to significant decreased titers of 1-BD. Finally, these two ALDHs were separately overexpressed in PA-3, and titer of 1-BD was promoted to 1.36 g/L at 72 h in shake flask. Totally in this work, we provided a forward ß-oxidation pathway for 1-BD production from KWO, and the roles of ALDHs were confirmed.

Recirculating used cooking oil and Nagkesar seed shells in dual-stage catalytic biodiesel synthesis with C1-C3 alcohols.

The presented study discusses biodiesel synthesis by utilizing two wastes: Mesua ferrea Linn (MFL) seed shells (inert support for developing catalysts) and used cooking oil (feedstock). The MFL shells were used for heterogeneous acid and base catalyst development through carbonization, steam activation and subsequent doping of H2SO4 or KOH, which upon instrumental examination showed effective doping of functional groups on the MFL char. The conversion approach uses methanol with sulfonated char (SC) for esterification, while the second stage utilizes 2-propanol for transesterification with KOH-doped char (KC) as a catalyst. Both stages optimize 5 controlling parameters such as mixing intensity, duration of reaction, catalyst load, alcohol concentration and reaction temperature in an L16 Taguchi experimental matrix. Thus, the obtained biodiesel has an ester content of 99.16%, while 97.35% of the free fatty acids (FFA) were converted, resulting in the product showing improved physico-chemical properties as assessed through fuel characterization tests. Reusability tests for the catalysts showed 4 reuses for acid catalyst compared to 9 reuses for base catalyst. Catalyst development costs were only $1.27/kg for activated char, while due to reuse, the prepared catalysts cost only $0.53/kg of biodiesel. Hence, the catalytic process holds great potential for commercialization if scaled up appropriately.

Fed-in-situ biological reduction treatment of food waste via high-temperature-resistant oil degrading microbial consortium.

This study aims to construct a high-temperature-resistant microbial consortium to effectively degrade oily food waste by Fed-in-situ biological reduction treatment (FBRT). Oil degrading bacteria were screened under thermophilic conditions of mineral salt medium with increased oil content. The oil degradation and emulsification ability of each stain was evaluated and their synergetic improvement was further confirmed. Consortium of Bacillus tequilensis, Bacillus licheniformis, Bacillus sonorensis and Ureibacillus thermosphaericus was selected and applicated as bacterial agents in FBRT under 55 °C. Changes in pH, moisture, bacterial community and key components of food waste were monitored for 5 days during processing. Facilitated by the bacterial consortium, FBRT gave superior total mass reduction (86.61 ± 0.58% vs. 67.25 ± 1.63%) and non-volatile solids reduction (65.91 ± 1.53% vs. 28.53 ± 2.29%) compared with negative control, the feasibility and efficiency of present FBRT providing a promising in-situ disposal strategy for rapid reduction of oily food waste.

Synergetic degradation of waste oil by constructed bacterial consortium for rapid in-situ reduction of kitchen waste.

Traditional composting of kitchen waste (KW) is cost- and time-intensive, requiring procedures of collection, transport and composing. Consequently, the direct in-situ reduction of KW via treatment at the point of collection is gaining increasing attention. However, high oil content of KW causes separation and degradation issues due to its low bioavailability and the hydrophobicity, and therefore greatly limiting the direct application of in-situ methods for mass reduction. To overcome this, a bacterial consortium of Pseudomonas putida and Bacillus amyloliquefaciens was constructed, which exhibited a synergistically improved oil degrading ability for lipase-catalyzed hydrolysis, fatty acids ß-oxidation, biosurfactant production and surface tension reduction, and the degradation ratio reached 58.96% within 48 h when the initial KW oil concentration was 8.0%. The in-situ aerobic digestion of KW was further performed in a 20-L stirred-tank reactor, the content of KW oil (34.72 ± 2.05% of total solids, w/w) was rapidly decreased with a simultaneous increase in both lipase activity and in microbial cell numbers, and the degradation ratio reached 57.38%. The synergetic effect of the two strains including B. amyloliquefaciens and P. putida promoted the decomposition process of KW oil, which also paved the way for an efficient degradation strategy to support the application potential of in-situ microbial reduction of KW.

Salmo salar fish waste oil: Fatty acids composition and antibacterial activity.

BACKGROUND AND AIMS: Fish by-products are generally used to produce fishmeal or fertilizers, with fish oil as a by-product. Despite their importance, fish wastes are still poorly explored and characterized and more studies are needed to reveal their potentiality. The goal of the present study was to qualitatively characterize and investigate the antimicrobial effects of the fish oil extracted from Salmo salar waste samples and to evaluate the potential use of these compounds for treating pathogen infections. METHODS: Salmo salar waste samples were divided in two groups: heads and soft tissues. Fatty acids composition, and in particular the content in saturated (SAFAs), mono-unsaturated (MUFAs) and Polyunsaturated (PUFAs) fatty acids, was characterized through GC/MS Thermo Focus GC-DSQ II equipped with a ZB-5 fused silica capillary tubes column. The antimicrobial activity of the salmon waste oils was evaluated through the Minimum Inhibitory Concentration assay and the antibiotics contamination was determined by Liquid Chromatography with tandem Mass Spectrometry (LC-MS/MS) analysis. All experiments were done at least in triplicate. RESULTS: GC/MS analysis has shown the specific fatty acid composition of the salmon waste oils and their enrichment in MUFAs and PUFAs, with special reference to omega-3, -6, -7, -9 fatty acids. Furthermore, our study has highlighted the antimicrobial activity of the fish waste oil samples against two Gram+ and Gram- bacterial strains. CONCLUSIONS: These data confirm that the fish waste is still quantitatively and qualitatively an important source of available biological properties that could be extracted and utilized representing an important strategy to counteract infective diseases in the context of the circular economy.

An innovative method to reduce oil waste using a sensor made of recycled material to evaluate engine oil life in automotive workshops.

In this work, a capacitive sensor made of recycled material is proposed to monitor oil quality in automotive workshops in order to reduce the waste of useful lubricant oil caused by shorter periods of use than those established by the manufacturers. The sensor was fabricated from a recycled aluminum heat sink and used to measure the permittivity of oil samples. The proposed method was compared with Fourier-transform infrared spectroscopy analysis to evaluate degradation parameters, as described in standard practice ASTM E-2412. The obtained results showed good agreement between both techniques, validating the use of the proposed sensor to evaluate oil condition. The use of permittivity measurements could be used to evaluate oil quality in an easier, faster, and economical way compared with other laboratory tests.

Direct combustion of waste oil in domestic stove by an internal heat re-circulation atomization technology: Emission and performance analysis.

Direct use of waste oil as fuel to meet the residential energy demands, is very attractive due to its potentials to decrease fossil fuel consumption, reduce pollution and increase sustainability. This paper uses a domestic stove with an internal heat re-circulation and self-atomization technology to burn yellow waste cooking oil (WCO-1), brown waste cooking oil (WCO-2) and waste lubricant oil (WLO). Emission factors (EFs), energy efficiency and modified combustion efficiency (MCE) of this combined fuel/stove system were determined under space-heating and cooking modes. The results showed that EFs of CO, PM2.5, total 16 PAHs and corresponding toxic equivalent quantity (TEQ) values ranged from 2.18 × 103 to 4.90 × 103 mg/MJnet, 16.36-69.40 mg/MJnet, 2.39-12.93 µg/MJnet and 0.16-0.92 µg of TEQ/MJnet. WCO-1 was verified to be the cleanest fuel with the highest energy efficiency (85.3 ± 3.3% and 90.4 ± 2.2%) and lowest emission levels, such as NO (53.75 ± 2.62 and 37.09 ± 5.41 mg/MJnet), NO2 (82.40 ± 3.96 and 56.87 ± 8.29 mg/MJnet) and PM2.5 (20.94 ± 6.55 and 16.35 ± 5.06 mg/MJnet) compared to WCO-2 and WLO. The estimated total cost of using waste oil for each household in winter was much cheaper than some current available clean energy means, including only USD$ 400 of stove price and USD$ 250/ton of fuel per year. It is a promising candidate choice for replacing low-quality solid fuels in rural China and 2.62 million rural households would achieve environmental and economic benefits if promoting direct combustion of waste oil for daily heating and cooking.