预处理技术--家庭生物废弃物处理过程中的微塑料制造者

Mechanical pretreatment is an indispensable process in biological treatment plants that remove plastics and other impurities from household biogenic waste(HBW).However,the imperfect separation of plastics in these pretreatment methods has raised concerns that they pose a secondary formation risk for microplastics(MPs).To validate this presumption,herein,quantities and properties of plastic debris and MPs larger than 50 μm were examined in the full chain of three different pretreatment methods in six plants.These facilities received HBW with or without prior depackaging at the source.The key points in the secondary formation of MPs were identified.Moreover,flux estimates of MPs were released,and an analysis of MPs sources was provided to develop an overview of their fate in HBW pretreatment.Pretreated output can contain a maximum of(1673±279) to(3198±263) MP particles per kilogram of wet weight(particles·kg^(-1)ww) for those undepackaged at source,and secondary MPs formation is primarily attributed to biomass crushers,biohydrolysis reactors,and rough shredders.Comparatively,HBW depackaged at the source can greatly reduce MPs by 8%-72%,regardless of pretreatment processes.Before pretreatment,4.6-205.6 million MP particles were present in 100 tonnes of HBW.MPs are produced at a rate of 741.11-33124.22 billion MP particles annually in anaerobic digester feedstock(ADF).This study demonstrated that HBW pretreatment is a competitive source of MPs and emphasized the importance of implementing municipal solid waste segregation at the source.Furthermore,depackaging biogenic waste at the source is recommended to substantially alleviate the negative effect of pretreatment on MPs formation.

Effects of ultrasonic pretreatment on sludge dewaterability and extracellular polymeric substances distribution in mesophilic anaerobic digestion

Effect of ultrasonic pretreatment on sludge dewaterability was determined and the fate of extracellular polymeric substances （EPS） matrix in mesophilic anaerobic digestion after ultrasonic pretreatment was studied. Characteristics of proteins （PN）, polysaccharides （PS）, excitation-emission matrix （EEM） fluorescence spectroscopy and molecular weight （MW） distribution of dissolved organic matters （DOM） in different EPS fractions were evaluated. The results showed that after ultrasonic pretreatment, the normalized capillary suction time （CST） decreased from 44.4 to 11.1 （sec·L）/g total suspended solids （TSS） during anaerobic digestion, indicating that sludge dewaterability was greatly improved. The normalized CST was significantly correlated with PN concentration （R2 = 0.92, p 〈 0.01） and the PN/PS ratio （R2 = 0.84, p 〈 0.01） in the loosely bound EPS （LB-EPS） fraction. Meanwhile, the average MW of DOM in the LB- EPS and tightly bound EPS （TB-EPS） fractions also had a good correlation with the normalized CST （R2 〉 0.66, p 〈 0.01）. According to EEM fluorescence spectroscopy, tryptophan-like substances intensities in the slime, LB-EPS and TB-EPS fractions were correlated with the normalized CST. The organic matters in the EPS matrix played an important role in influencing sludge dewaterability.

Predicting the elemental compositions of solid waste using ATR-FTIR and machine learning

Elemental composition is a key parameter in solid waste treatment and disposal. This study has proposed a method based on infrared spectroscopy and machine learning algorithms that can rapidly predict the elemental composition (C, H, N, S) of solid waste. Both noise and moisture spectral interference that may occur in practical application are investigated. By comparing two feature selection methods and five machine learning algorithms, the most suitable models are selected. Moreover, the impacts of noise and moisture on the models are discussed, with paper, plastic, textiles, wood, and leather as examples of recyclable waste components. The results show that the combination of the feature selection and K-nearest neighbor (KNN) approaches exhibits the best prediction performance and generalization ability. Particularly, the coefficient of determination (R2) of the validation set, cross validation and test set are higher than 0.93, 0.89, and 0.97 for predicting the C, H, and N contents, respectively. Further, KNN is less sensitive to noise. Under moisture interference, the combination of feature selection and support vector regression or partial least-squares regression shows satisfactory results. Therefore, the elemental compositions of solid waste are quickly and accurately predicted under noise and moisture disturbances using infrared spectroscopy and machine learning algorithms.

Material flow analysis and global warming potential assessment of an industrial insect-based bioconversion plant using housefly larvae

The significant increase in the demand for biomass waste treatment after garbage classification has led to housefly larvae treatment becoming an attractive treatment option.It can provide a source of protein while treating biomass waste,which means that nutrients can be returned to the natural food chain.However,the performance of this technology in terms of its environmental impacts is still unclear,particularly with regards to global warming potential(GWP).This study used a life cycle assessment(LCA)approach to assess a housefly larvae treatment plant with a treatment capacity of 50 tons of biomass waste per day.The LCA results showed that the 95% confidence intervals for the GWP in summer and winter were determined to be 24.46-32.81 kg CO_(2) equivalent(CO_(2)-eq)/ton biomass waste and5.37-10.08 kg CO_(2)-eq/ton biomass waste,respectively.The greater GWP value in summer is due to the longer ventilation time and higher ventilation intensity in summer,which consumes more power.The main GWP contributions are from(1)electricity needs(accounting for 78.6% of emissions in summer and 70.2%in winter)and(2)product substitution by mature housefly larvae and compost(both summer and winter accounting for 96.8% of carbon reduction).

Fate of antibiotics and antibiotic resistance genes in a full-scale restaurant food waste treatment plant:Implications of the roles beyond heavy metals and mobile genetic elements

Is our food safe and free of the crisis of antibiotics and antibiotic resistance (AR)?And will the derived food waste (FW) impose AR risk to the environment after biological treatment? This study used restaurant FW leachates flowing through a 200 tons-waste/day biological treatment plant as a window to investigate the fate of antibiotics and antibiotic-resistance genes (ARGs) during the acceptance and treatment of FW.Sulfonamides (sulfamethazine,sulfamethoxazole) and quinolones (ciprofloxacin,enrofloxacin,ofloxacin) were detected during FW treatment,while tetracyclines,macrolides and chloramphenicols were not observable.ARGs encoding resistance to sulfonamides,tetracyclines and macrolides emerged in FW leachates.Material flow analysis illustrated that the total amount of antibiotics (except sulfamethazine) and ARGs were constant during FW treatment processes.Both the concentration and total amount of most antibiotics and ARGs fluctuated during treatment,physical processes (screening,centrifugation,solid-liquid and oil-water separation) did not decrease antibiotic or ARGs concentrations or total levels permanently;the affiliated wastewater treatment plant appeared to remove sulfonamides and most ARGs concentrations and total amount.Heavy metals Ni,Co and Cu were important for disseminating antibiotics concentrations and MGEs for distributing ARGs concentrations.Humic substances (fulvic acids,hydrophilic fractions),C-associated and N-associated contents were essential for the distribution of the total amounts of antibiotics and ARGs.Overall,this study implied that human food might not be free of antibiotics and ARGs,and FW was an underestimated AR pool with various determinants.Nonetheless,derived hazards of FW could be mitigated through biological treatment with well-planned daily operations.

Estimating source strengths of HCl and SO_2 emissions in the flue gas from waste incineration

HCl and SO_2 emission is one of the major concerns related to municipal solid waste incinerator(MSWI). In this study, a material flow analysis model was developed to estimate the HCl and SO_2 concentrations in the MSWI flue gases(FGs), and their concentrations in the full-scale MSWI were monitored. The calculated concentrations of HCl and SO_2 in the FG were 770–1300 mg/Nm^3 and 150–640 mg/Nm^3, respectively, in close agreement with the monitored values. More than 99% of Cl and 92% of S from the FG were captured into solid residues by the air pollution control(APC) systems. Moreover, since only 48.4%–67.5% of Cl and 21.3%–53.4% of S were transferred to the FG from the municipal solid waste(MSW), it was more reliable to estimate the source strengths and release amounts of HCl and SO_2 in the FG based on the amounts of Cl and S in the APC residues(AR) and exhaust gas rather than in the MSW. This simple method is easily applicable and the estimated results could provide scientific basis for the appropriate design and operation of the APC systems as well as corrosion control of heat recovery systems.

Impact of municipal solid waste incineration on heavy metals in the surrounding soils by multivariate analysis and lead isotope analysis

Municipal solid waste(MSW) incineration has become an important anthropogenic source of heavy metals(HMs) to the environment. However, assessing the impact of MSW incineration on HMs in the environment, especially soils, can be a challenging task because of various HM sources. To investigate the effect of MSW incineration on HMs in soils, soil samples collected at different distances from four MSW incinerators in Shanghai, China were analyzed for their contents of eight HMs(antimony, cadmium, chromium, copper,lead, mercury, nickel, and zinc) and lead(Pb) isotope ratios. Source identification and apportionment of HMs were accomplished using principal component analysis and Pb isotope analysis. Results indicated that the relatively high contents of cadmium, lead,antimony, and zinc in the soils at 250 m and 750–1250 m away from the MSW incinerators were related to MSW incineration, while the elevated contents of the other four HMs were associated with other anthropogenic activities. Based on Pb isotope analysis, the contribution ratio of MSW incineration(which had been operated for more than 14 years)to the accumulation of Pb in soil was approximately 10% on average, which was lower than coal combustion only. Incinerator emissions of Pb could have a measurable effect on the soil contamination within a limited area(≤1500 m).

Road to full bioconversion of biowaste to biochemicals centering on chain elongation: A mini review

Production of biochemicals from waste streams has been attracting increasing worldwide interest to achieve climate protection goals.Chain elongation(CE)for production of mediumchain carboxylic acids(MCCAs,especially caproate,enanthate and caprylate)from diverse biowaste has emerged as a potential economic and environmental technology for a sustainable society.The present mini review summarizes the research utilizing various synthetic or real waste-derived substrates available for MCCA production.Additionally,the microbial characteristics of the CE process are surveyed and discussed.Considering that a large proportion of recalcitrantly biodegradable biowaste and residues cannot be further utilized by CE systems and remain to be treated and disposed,we propose here a loop concept of bioconversion of biowaste to MCCAs making full use of the biowaste with zero emission.This could make possible an alternative technology for synthesis of value-added products from a wide range of biowaste,or even non-biodegradable waste(such as,plastics and rubbers).Meanwhile,the remaining scientific questions,unsolved problems,application potential and possible developments for this technology are discussed.

A nanoscale observation to explain the discrepancy of electron exchange capacities between biochar containing comparable surface redox-active moieties

Biochar,possessing electron exchange capacities(EEC),is generally involved in environmental redox reactions due to the presence of redox-active moieties(RAMs).The phenomenon that chars containing comparable RAMs possess differential EEC revealed that the accessibility of RAMs is important to the redox properties.However,many studies have focused on the type of RAMs,whereas the distribution has been insufficiently investigated.Herein,we achieved nanoscale observation of electroactive moieties on the surface of six chars using a conductive atomic force microscope.For the two specific kinds of chars with submicron particles and opposite current distributions,the submicron particles took up only 1-4‰wt of biochar accounting for approximately 30-50%of electron-donating capacity(EDC),and electron-accepting capacity(EAC)became 87%and 1.40 times as before after removing submicron particles,respectively.Meanwhile,the combined impact of RAMs and surface topography(that uneven distribution of RAMs resulted in outstanding EEC by enhancing accessibility)was clarified.Furthermore,direct evidence of the link between char structure and EEC(that condensed aromatic structures were indispensable to EAC while both heteroatoms and amorphous aromatics contributed to EDC)was established.These findings can aid in understanding the functions of biochar in biotic and abiotic redox processes.

Treatment and resource recovery from inorganic fluoride-containing waste produced by the pesticide industry

The rapid development of the fluorinated pesticide industry has produced a large amount of fluorine-containing hazardous waste, especially inorganic fluoride-containing waste（IFCW）. A two-step process, including extraction and recovery, was developed to recover fluorine as synthetic cryolite from IFCW produced by the pesticide industry. The optimum conditions for extraction were found to be a temperature of 75℃, an initial p H（p Hi） of 12, a4-hr incubation time and a liquid-to-solid ratio of 40 m L/g; these conditions resulted in a fluorine extraction ratio of 99.0%. The effects of p H and the F/Al molar ratio on fluorine recovery and the compositional, mineralogical and morphological characteristics of the cryolite products were investigated. Field-emission scanning electron microscopy of recovered precipitates showed changes in morphology with the F/Al molar ratio. Coupling Fourier transform and infrared spectroscopy, X-ray diffraction indicated that the formation of Al F3-6was restricted as increasing p H. Both the amount of fluorine recovered and the quality of the cryolite were optimized at initial p H = 3 and a F/Al molar ratio 5.75. This study proposed a reliable and environmentally friendly method for the treatment of fluoridecontaining wastes, which could be suitable for industrial applications.

Biosorption of Cr(Ⅲ)from aqueous solution by freeze-dried activated sludge:Equilibrium,kinetic and thermodynamic studies

Batch biosorption experiments were conducted to remove Cr(Ⅲ)from aqueous solutions using activated sludge from a sewage treatment plant.An investigation was conducted on the effects of the initial pH,contact time,temperature,and initial Cr(Ⅲ)concentration in the biosorption process.The results revealed that the activated sludge exhibited the highest Cr(Ⅲ)uptake capacity(120 mg·g^(–1))at 45℃,initial pH of 4,and initial Cr(Ⅲ)concentration of 100 mg·L^(–1).The biosorption results obtained at various temperatures showed that the biosorption pattern accurately followed the Langmuir model.The calculated thermodynamic parameters,ΔGo(–0.8––4.58 kJ·mol^(–1)),ΔHo(15.6–44.4 kJ·mol^(–1)),andΔSo(0.06–0.15 kJ·mol^(–1)·K^(–1))clearly indicated that the biosorption process was feasible,spontaneous,endothermic,and physical.The pseudo first-order and second-order kinetic models were adopted to describe the experimental data,which revealed that the Cr(Ⅲ)biosorption process conformed to the second-order rate expression and the biosorption rate constants decreased with increasing Cr(Ⅲ)concentration.The analysis of the values of biosorption activation energy(Ea=–7 kJ·mol^(–1))and the intraparticle diffusion model demonstrated that Cr(Ⅲ)biosorption was film-diffusion-controlled.

Feasibility of housefly larvae-mediated vermicomposting for recycling food waste added digestate as additive

The development of methods for the efficient treatment and application of food waste digestate is an important research goal.Vermicomposting via housefly larvae is an efficient way to reduce food waste and achieve its valorization,however,studies on the application and performance of digestate in vermicomposting are rarely.The present study aimed to investigate the feasibility of the co-treatment of food waste and digestate as an additive via larvae.Restaurant food waste(RFW)and household food waste(HFW)were selected to assess the effects of waste type on vermicomposting performance and larval quality.Waste reduction rates of 50.9%–57.8%were observed in the vermicomposting of food waste mixed with digestate at a ratio of 25%,which were slightly lower than those for treatments without the addition of digestate(62.8%–65.9%).The addition of digestate increased the germination index,with a maximum value of 82%in the RFW treatments with 25%digestate,and decreased the respiration activity,with a minimum value of 30 mg-O_(2)/g-TS.The larval productivity of 13.9%in the RFW treatment system with a digestate rate of 25%was lower that without digestate(19.5%).Materials balance shows that larval biomass and metabolic equivalent had decreasing trends as the amount of digestate increased and HFW vermicomposting exhibited lower bioconversion efficiency than that of RFW treatment system regardless of the addition of digestate.These results suggest that mixing digestate at a low ratio(25%)during vermicomposting of foodwaste especially RFW could lead to considerable larval biomass and generate relatively stable residues.

Molecular behavior and interactions with microbes during anaerobic degradation of bio-derived DOM in waste leachate

It is the key to control bio-derived dissolved organic matters (DOM) in order to reduce the effluent concentration of wastewater treatment, especially for waste leachate with high organic contaminants. In the present study, the anaerobic degradation of aerobically stabilized DOM was investigated with DOM substrate isolated through electrodialysis. The degradation of bio-derived DOM was confirmed by reduction of 15%of total organic carbon in 100 days.We characterized the molecular behavior of bio-derived DOM by coupling molecular and biological information analysis. Venn based Sankey diagram of mass features showed the transformation of bio-derived DOM mass features. Occurrence frequency analysis divided mass features into six categories so as to distinguish the fates of intermediate metabolites and persistent compounds. Reactivity continuum model and machine learning technologies realized the semi-quantitative determination on the kinetics of DOM mass features in the form of pseudo-first order, and confirmed the reduction of inert mass features. Furthermore, network analysis statistically establish relationship between DOM mass features and microbes to identify the active microbes that are able to utilize bio-derived DOM. This work confirmed the biological technology is still effective in controlling recalcitrant bio-derived DOM during wastewater treatment.

Correction to:Achievements and policy trends of extended producer responsibility for plastic packaging waste in Europe

Correction to:WasteDisposal&SustainableEnergy(2022)4:91-103 https://doi.0rg/10.1007/s42768-022-00098-z The section‘Conflict of Interest'has been amended:‘Pinjing He is the Editorial Board member of Waste Disposal&Sustainable Energy'The revised‘Conflict of Interest'is as follows:Pinjing He is the Editorial Board member of Waste Disposal&Sustainable Energy.

Recovery of phosphorus as struvite from sewage sludge ash

Phosphorus （P） is an element vital for all living organisms, yet the world＇s reserves of phosphate rock are becoming depleted. This study investigated an effective P recovery method from sludge ash via struvite precipitation. Results showed that more than 95% of the total P content was extracted from sludge ash by applying 0.5 mol/L HC1 at a liquid/solid ratio of 50 mL/g. Although heavy metal leaching also occurred during P extraction, cation exchange resin efticiently removed the heavy metals from the P-rich solution. Orthogonal tests showed that the optimal parameters for P precipitation as struvite would be a Mg：N：P molar ratio of 1.6：1.6：1 at pH 10.0. X-ray diffraction analysis validated the formation of struvite. Further investigations revealed that the harvested precipitate had a high struvite content （97%）, high P bioavailability （94%）, and low heavy metal content, which could be considered a high quality fertilizer.

Metal distribution characteristic of MSWI bottom ash in view of metal recovery

Bottom ash is the major by-product of municipal solid waste incineration（MSWI）, and is often reused as an engineering material, such as road-base aggregate. However, some metals（especially aluminum） in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated. The metal concentrations in these bottom ashes were lower than that generated in other developed countries. Specifically, the contents of Al,Fe, Cu and Zn were 18.9–29.2, 25.5–32.3, 0.7–1.0 and 1.6–2.5 g/kg, respectively. Moreover,44.9–57.0 wt.% of Al and 55.6–75.4 wt.% of Fe were distributed in bottom ash particles smaller than 5 mm. Similarly, 46.6–79.7 wt.% of Cu and 42.9–74.2 wt.% of Zn were concentrated in particles smaller than 3 mm. The Fe in the bottom ash mainly existed as hematite, and its chemical speciation was considered to limit the recovery efficiency of magnetic separation.

Enhanced anaerobic digestion and sludge dewaterability by alkaline pretreatment and its mechanism

To investigate the influences of alkaline pretreatment on anaerobic digestion （AD） and sludge dewaterability after AD, waste activated sludge was adjusted to different pH values （8, 9, 10, 1 1, 12） and placed at ambient temperature for 24 hr. The samples were then adjusted to the initial pH and subjected to 25 days of AD. The results showed that, when compared with the control （pH 6.8）, total suspended solids （TSS） and volatile suspended solids （VSS） reduction following pretreatment at pH 9-11 increased by 10.7%-13.1% and 6.5%- 12.8%, respectively, while biogas production improved by 7.2%-15.4%. Additionally, significant enhancement of sludge dewaterability after AD occurred when pretreatment at pH 8-9 was conducted. The proteins and carbohydrates transferred from the pellet and tightly bound extracellular polymeric substances （TB-EPS） fractions to the slime and loosely bound EPS （LB-EPS） fractions after pretreatment and during the AD process, and the concentrations of proteins and carbohydrates in the slime fraction had a good linear relationship with the normalized capillary suction time （CST）. During the AD process, the normalized CST was positively correlated with the organic materials in the loosely bound fraction of the sludge matrix （R2/〉 0.700, p 〈 0.01）, while it was negatively correlated with the organic materials in the tightly bound fraction （R2≥ 0.702, p 〈 0.01）. These results suggest that alkaline pretreatment could break the EPS matrix and release inner organic materials, thus influencing the efficiency of the AD process and dewaterability after AD.

Leaching toxicity characteristics of municipal solid waste incineration bottom ash

The continuously increasing production of municipal solid waste incineration bottom ash （MSWIBA） has promoted its utilization as construction material and raised environmental concern. The physico-chemical properties and leaching behavior of MSWIBA were studied, and ecotoxicological testing using a luminescent bacterium bioassay was performed to assess the ecological pollution risks associated with its leached constituents. The MSWIBA was leached by two types of leachants, H2SO4/HNO3 and HAc solution, at different liquid to solid ratios and contact times. The concentrations of heavy metals and anions in the leachates were analyzed. Multi- variate statistical analyses, including principle component analysis, Pearson＇s correlation analysis and hierarchical cluster analysis, were used to evaluate the contributions of the constituents to the toxicity （ECso） of the MSWIBA leachate. The statistical analyses of the ecotoxicological results showed that the Ba, Cr, Cu, Pb, F and total organic carbon （TOC） concentrations were closely correlated with the ECso value, and these substances were the main contributors to the ecotoxicity of the MSWIBA leachate. In addition, the cluster of these variables indicated similar leaching behaviors. Overall, the research demonstrated that the ecotoxicological risks resulting from MSWIBA leaching could be assessed before its utilization, which provides crucial information for the adaptation of MSWIBA as alternative materials.

Bioaerosolization behavior along sewage sludge biostabilization

Biostabilization is a cost-effective method for the beneficial utilization of sewage sludge.However,during the operation of sludge biostabilization,some microbial species could be released into the atmospheric environment from the solid-phase of sludge easily and present a high risk to human health.This study aimed to evaluate the risk of bioaerosol during sludge biostabilization.We found a total of nine bacterial phyla,one archaeal phylum,and two fungal phyla in the bioaerosol samples.Among them,Proteobacteria,Actinobacteria,Bacteroidetes,and Ascomycota were the dominant phyla.In addition,the bioaerosolization indexes(BI)of prokaryotic phyla and flingal phyla ranged 0-45 and 0-487,respectively.Mass ilia y Pseudarthrobacter,Pseudomonas,Tremellales spp.,and Fusarium were the preferentially aerosolized microbial genera with maximum bioaerosolization indexes of 19962,10360,1802,3055,and 7398.The bioaerosol concentration during the biostabilization ranged from 160 to 1440 cell/m^(3),and we identified species such as Stenotrophomonas rhizophila and Fusarium graminerum with high bioaerosolization indexes that could be threats to human health.Euryachaeota,which belongs to archaeal phyla,had the highest biostabilization index in our study.We also found that Pseudarthrobacter was the easiest to aerosolize during the sludge biostabilization process.

Humification characterization of biochar and its potential as a composting amendment

Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results showed that wood biochar and bamboo biochar samples were 60%-80% more hydrophobic than those of rice husk biochar and rice husk ash. In addition, the acidity was 3.88 mmol/g from the total functional groups and 1.03 mmol/g from the carboxyl groups/lactones/phenols found in the wood biochar sample, which were about 1.5 times greater than those of the bamboo biochar sample. These functional groups could be used to determine the sorptive capacity of biochar for ionic solutes and water content and to increase the degradation of compost organics. The wood biochar sample was found to have the most humification materials （fulvic acid-like material ＋ humic acid-like material） in the water-extractable fraction, which was 3-10 times higher than that in the rice husk biochar and rice husk ash; humified materials were not detected in the bamboo biochar sample. Humification materials in biochar may be involved in increasing the proportion of humic acid-like materials in humic-like substances within the compost product. Wood biochar had better hydrophobic, sorptive, aromatic, and humification properties compared to other biochars, suggesting that it may be used in composting in order to exert its effect as both a bulking agent and a composting amendment during the solid waste composting process.