Effects of thermally pretreated temperature on bio-hydrogen production from sewage sludge

Hydrogen can be obtained by anaerobic fermentation of sewage sludge. Therefore, in this paper the effects of thermally pretreated temperatures on hydrogen production from sewage sludge were investigated under different pre-treatment conditions. In the thermal pretreatment, some microbial matters of sludge were converted into soluble matters from insoluble ones. As a result, the suspended solid（SS） and volatile suspended solid（VSS） of sludge decreased and the concentration of soluble COD（SCOD） increased, including soluble carbohydrates and proteins. The experimental results showed that all of those pretreated sludge could produce hydrogen by anaerobic fermentation and the hydrogen yields under the temperatures of 121℃ and 50℃ were 12.23 ml/g VS（most） and 1.17 ml/g VS （least）, respectively. It illuminated that the hydrogen yield of sludge was affected by the thermally pretreated temperatures. Additionally, the endurance of high hydrogen yield depended on the translation of microbial matters and inhibition of methanogens in the sludge. The temperatures of 100℃ and 121℃ （treated time, 30 min） could kill or inhibit completely the methanogens while the others could not. To produce hydrogen and save energy, 100℃ was chosen as the optimal temperature for thermal pretrcatment. The composition changes in liquid phase in the fermentation process were also discussed. The SCOD of sludge increased, which was affected by the pretreatment temperature. The production of volatile fatty acids in the anaerobic fermentation increased with the pretreatment temperature.

Etherification of Alkali-pretreated Sugarcane Bagasse Cellulose in Tetrahydrofuran

Sugarcane bagasse(SCB)is an important by-product in the sugar industry.It is a source of cellulose fibers or cellulose for paper mills and textiles factories.In this study,SCB was ethyl etherified in tetrahydrofuran(THF)after alkali pretreatment.The alkali concentration for the pretreatment,the ratio of ethyl bromide(EtBr)to dried SCB in the reaction,reaction time,and temperature were investigated for the etherification of SCB.The ethoxyl content and characterization of the product were determined using headspace gas chromatography(HS-GC),Fourier Transform Infrared(FT-IR)and 13C-NMR spectroscopy,respectively.It was found that SCB was well-etherified with EtBr in alkali-THF.Upon ethylation of SCB,the ethoxyl content of the product was high when the alkali concentration and the ratio of EtBr to dried SCB were controlled from 50%to 75%and 4:1(V/w)to 6:1(V/w),respectively.The reaction occurred optimally when the temperature was controlled below 110℃;above this temperature,the degree of etherification decreased.The thermal stability of ethylated SCB was higher than that of SCB but slightly lower than that of commercial ethyl cellulose.Ethylated SCB has the potential to form composites with many materials because it is soluble in a wide variety of solvents.

Characterization of wet microalgal cells pretreated with steam for lipid extraction

Steam pretreatment was employed to disrupt Microalgal cells for lipids extraction.Effects of steam pretreatment on microstructure of microalgal cells were investigated through scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Effect of treatment on lipid extraction was also studied.Microalgal cell walls were distorted after steam pretreatment due to the hydrolysis of organic macromolecules contained in cell wall.Maximum curvature was increased from 1.88×10^(-6) m^(-1) to 1.43×10^(-7) m^(-1) after treatment with the steam at 130℃.The fractal dimension of microalgal cells increased from 1.25 to 1.30 after pretreatment for 15 min,and further increased to 1.47 when the pretreatment time was increased to 60 min.Increased steam pretreatment temperature and time enhanced the hydrolysis of organic macromolecules,and finally destroyed microalgal cell walls at pretreatment temperature of 130℃and pretreatment time of 60 min.Lipid extracted from wet microalgal was significantly increased(2.1-fold)after pretreatment.

Production of Fermentable Sugars from Organosolv Pretreated Cassava Peels

Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study was designed to investigate lignocellulolytic organisms that would effectively support the bioconversion of organosolv pretreated cassava peels to fermentable sugars. Decaying cassava peels were collected into sterile bottles and microorganisms isolated, characterized and screened for lignocellulolytic enzymes production. Optimum temperature, pH and nutrient sources for enzyme production were determined. Organosolv pretreatment was carried out using methanol with varied concentration of catalyst (0.01 - 3 M), reaction time (15 - 60 min) and substrate size. Crude enzymes (cellulase and xylanase) from the isolates were added to the pretreated peels and bioconversion was monitored by measuring the concentration of reducing sugar and calculating the percentage peel hydrolysis. The fermentable sugars produced were quantified using gas chromatography. Pseudomonas fluorescens and Aspergillus terreus were isolated. P. fluorescens produces 2.8 u/mL of crude enzymes optimally at 50°C and pH 8 while A. terreus produces 3.4 u/mL optimally at 40°C, pH 6. Both isolates utilizes CarboxyMethylCellulose (CMC) and yeast extract as their best carbon and nitrogen sources. Highest percentage of peel hydrolysis was 67% for P. fluorescens at 0.01 M and 0.05 M for A. terreus (94%). Highest concentration of fermentable sugar was produced by A. terreus crude enzyme (331.79 mg/L glucose, 45.3 mg/L rhamnose and 46.52 mg/L xylose). P. fluorescens and A. terreus effectively supported the bioconversion of organosolv pretreated cassava peels to fermentable sugars.

Thermal Decomposition of Bamboo Phyllostachys Edulis Pretreated with Ionic Liquids-Water Mixtures

The ionic liquid (IL)-water mixture pretreated bamboo (Phyllostachys edulis) samples were applied in the research of thermal decomposition. [BMIM]Cl (1-Butyl-3-methylimidazolium chloride)- water and [BMIM]BF4 (1-Butyl-3-methylimidazolium tetrafluoroborate)-water were used in pretreatment process. Compositions of the untreated bamboo and pretreated bamboo were compared. The results of X-ray diffraction analysis (XRD) were analyzed to explain the effect of ILs mixture on cellulose crystalline structure. The pretreated cellulose with [BMIM]Cl&#45 water mixture was tend to produce the more gaseous products, which were associated with the decomposition rate. The behavior of more CO and CH4 gaseous products and less tar in the thermal decomposition products could be attributed to ILs-water mixture pretreatment process. The potential and some problems of ILs-water mixture pretreatment method applied in thermal chemical conversion methods were also discussed.

Multi-Scale Structural Studies of Sequential Ionic Liquids and Alkali Pretreated Corn Stover and Sugarcane Bagasse

The complexity of plant cell walls impedes the conversion of cellulosic biomass to sugars. Pretreatment becomes a necessity to increase the digestibility of biomass. An in-depth understanding of the structure and underlying mechanisms governing deconstruction process is important. In the present study, the comprehensive investigation of morphological and structural changes in corn stover and sugarcane bagasse following ionic liquids dissolution and alkaline extraction was done using Fourier transform infrared spectroscopy, Thermogravimetric analysis, Confocal scanning laser microscopy, Atomic force microscopy and Dynamic light scattering studies. Both the substrates were pretreated with ILs 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate followed by alkaline extraction. The pronounced changes such as lignin, hemicelluloses removal and decreased cellulose crystallinity after the pretreatments lead to the structural transformation of matrix polymers. The enzymatic hydrolysis showed 90% theoretical sugar yield in case of sugarcane bagasse and 80% in corn stover following synergistically combined pretreatments.

Study on cationic dye adsorption of bio-chars prepared from thermal-alkaline-pretreated sludge

Sludge bio-char(SC)and thermal-alkaline treated sludge bio-char(TSC)were prepared from municipal sewage sludge(RS)and thermal-alkaline treated sludge sediments(STAS)through fast pyrolysis under nitrogen existence condition to remove cationic red X-GRL(A)and cationic yellow X-6G(B)from aqueous solutions.Results of adsorption experiment show that the adsorption capacities of TSC are better than the adsorption capacities of SC.The highest adsorption capacity of 47.65 mg/g for A and 45.41mg/g for B are obtained by TSC in an isotherm experiment at 2.0 g/L dosage and 25°C temperature.TSC adsorption for the two kinds of cationic dyes can be well fitted by pseudo-second-order kinetics model and Langmuir isotherm model.

Effect of Water Content on Crystalline Structure of Ionic Liquids Mixture Pretreated Microcrystalline Cellulose (MCC)

Microcrystalline cellulose (MCC) was pretreated by using ionic liquids (ILs)-water mixtures solvent with solid acid catalysts. Different amount of water was considerate as the main variable. The peak shift of pretreated sample was determined by FT-IR related to the water content. The XRD was applied to characterize the change in MCC crystalline structure. Thermal decomposition technique was applied to investigate the thermal stability of pretreated MCC. The result indicated that three state of samples were occurred in pretreated MCC sample which was related the amount of water in ILs mixture system. XRD result suggested that the raw sample was distorted and transformed into a less ordered intermediate structure and the smaller crystallite size in lump state sample was obtained which could lead to lower thermal stability. This study revealed the physical chemicals properties, characteristic of molecular structures in MCC using ILs-water mixtures.

Tribological properties of low-temperature time-dependent pretreated graphite for mechanical seal pairs in high-speed turbopump

The friction coefficient and wear rate of pretreated graphite with liquid nitrogen were obtained by using a ball-on-disk tester,and the wear of GCr15–graphite seal pairs with the low-temperature time-dependent pretreatment was discussed by comparing the wear morphology.The results show that liquid nitrogen pretreatment can affect the hardness and interlayer spacing of graphite.The range of the friction coefficients of pretreated graphite changes from 0.17 to 0.22.With the increase of liquid nitrogen pretreatment time,the wear mechanism of graphite would change from dominated three-body wear to adhesion wear.The experimental results of the mechanical seal with liquid nitrogen pretreatment show that the wear rate of stator is less than 0.00165 mm^(3)·N^(−1)·m^(−1),and the graphite shows a good low-temperature compatibility.

Comparison of mesophilic and thermophilic anaerobic digestions of thermal hydrolysis pretreated swine manure: Process performance,microbial communities and energy balance

Anaerobic digestion (AD) of swine manure (SM) commonly shows low biogas output and unsatisfactory economic performance. In this study, thermophilic AD (TAD, 50±1℃) was combined with thermal hydrolysis pretreatment (THP, 170℃/10 bar), to investigate its potential for maximizing biogas yield, securing successful digestion and microbial diversity, as well as improving energy balance. Four lab-scale continuously stirred tank reactors were operated for 300 days and compared with each other, i.e., reactor 1 (raw SM fed in mesophilic AD:RSM-MAD), reactor 2 (THP-treated SM fed in MAD:TSM-MAD), reactor 3 (RSM-TAD),and reactor 4 (TSM-TAD). The results showed that THP was efficient to increase methane production of SM, TSM-TAD mode led to the highest methane yield (129.8±40.5 mL-CH_(4)/gVS/day) among the tests (p <0.05). Although TAD was more likely to induce free ammonia (> 700 mg/L) or volatile fatty acids (> 6000 mg/L) accumulation compared with MAD in start-up phase, TSM-TAD treatment mode behaved a sustainable digestion process in a long-term operation. For TSM-TAD scenario, higher Shannon–Weaver (3.873) and lower Simpson index (0.061) indicated this mode ensured and enlarged the diversity of bacteria communities. Phylum Bathyarchaeota was dominant (59.3%-90.0%) in archaea community,followed by Euryarchaeota in the four reactors. RSM-MAD treatment mode achieved the highest energy output (4.65 GJ/day), TSM-TAD was less effective (-17.38 GJ/day) due to increased energy demands. Thus improving the energetic efficiency of THP units is recommended for the development of TSM-TAD treatment mode.

Anaerobic co-digestion of thermo-alkaline pretreated microalgae and sewage sludge: Methane potential and microbial community

To improve methane production from sewage sludge(SS),co-digestion of SS and microalgae(MA)was studied and the application of thermo-alkaline pretreatment to MA was evaluated.The results showed that thermo-alkaline pretreatment at 90℃ for 120 min on MA was the optimum pretreatment condition.Furthermore,when the volatile solids(VS)ratio of SS and MA was 1:2,the methane yield reached maximum(368.94 mL/g VS).Fourier transform infrared(FT-IR)and thermogravimetric analysis confirmed the synergetic effects of thermoalkaline pretreated MA on its co-digestion with SS.The analyses of microbial community indicated that Methanobacterium and Methanosarcina were the dominant methanogens during the co-digestion process.However,the relative abundance of Methanosarcina in thermoalkaline pretreated groups was higher compared to unpretreated groups.The microbial community structure might be affected by thermo-alkaline pretreatment rather than by the MA dosage in the co-digestion.

Advanced treatment of biologically pretreated coal gasification wastewater by a novel heterogeneous Fenton oxidation process

Sewage sludge from a biological wastewater treatment plant was converted into sewage sludge based activated carbon（SBAC） with Zn Cl2 as activation agent, which was used as a support for ferric oxides to form a catalyst（Fe Ox/SBAC） by a simple impregnation method.The new material was then used to improve the performance of Fenton oxidation of real biologically pretreated coal gasification wastewater（CGW）. The results indicated that the prepared Fe Ox/SBAC significantly enhanced the pollutant removal performance in the Fenton process, so that the treated wastewater was more biodegradable and less toxic. The best performance was obtained over a wide p H range from 2 to 7, temperature 30°C, 15 mg/L of H2O2 and 1 g/L of catalyst, and the treated effluent concentrations of COD, total phenols,BOD5 and TOC all met the discharge limits in China. Meanwhile, on the basis of significant inhibition by a radical scavenger in the heterogeneous Fenton process as well as the evolution of FT-IR spectra of pollutant-saturated Fe Ox/BAC with and without H2O2, it was deduced that the catalytic activity was responsible for generating hydroxyl radicals, and a possible reaction pathway and interface mechanism were proposed. Moreover, Fe Ox/SBAC showed superior stability over five successive oxidation runs. Thus, heterogeneous Fenton oxidation of biologically pretreated CGW by Fe Ox/SBAC, with the advantages of being economical, efficient and sustainable, holds promise for engineering application.

Role of tannin pretreatment in flotation separation of magnesite and dolomite

Flotation separation of magnesite and its calcium-containing carbonate minerals is a difficult problem.Recently,new regulat-ors have been proposed for magnesite flotation decalcification,although traditional regulators such as tannin,water glass,sodium carbon-ate,and sodium hexametaphosphate are more widely used in industry.However,they are rarely used as the main regulators in research because they perform poorly in magnesite and dolomite single-mineral flotation tests.Inspired by the limonite presedimentation method and the addition of a regulator to magnesite slurry mixing,we used a tannin pretreatment method for separating magnesite and dolomite.Microflotation experiments confirmed that the tannin pretreatment method selectively and largely reduces the flotation recovery rate of dolomite without affecting the flotation recovery rate of magnesite.Moreover,the contact angles of the tannin-pretreated magnesite and dolomite increased and decreased,respectively,in the presence of NaOl.Zeta potential and Fourier transform infrared analyses showed that the tannin pretreatment method efficiently hinders NaOl adsorption on the dolomite surface but does not affect NaOl adsorption on the magnesite surface.X-ray photoelectron spectroscopy and density functional theory calculations confirmed that tannin interacts more strongly with dolomite than with magnesite.

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 plas-tics 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 50μm 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 pri-marily 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 pro-duced at a rate of 741.11-33124.22billion MP partices 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.Furthemore,depack-aging biogenic waste at the source is recommended to substantially alleviate the negative effect of pre-treatment on MPs formation.

Synergetic Bioproduction of Short-Chain Fatty Acids from Waste Activated Sludge Intensified by the Combined Use of Potassium Ferrate and Biosurfactants

The synergetic effect and underlying mechanism of potassium ferrate(PF)with tea saponin(TS,a biosurfactant)in producing short chain fatty acids(SCFAs)from anaerobic fermentation of waste activated sludge(WAS)were explored in this work.Experimental results showed that 0.2 g PF(g TSS)^(-1)(total suspended solid)combined with 0.02 g TS(g TSS)^(-1) could further improve SCFAs’production,and the maximum SCFAs content reached 2008.7 mg COD L^(-1),which is 1.2 and 4.5 times higher than those with PF and TS individually added,respectively,and 5.3 times higher than that of blank WAS on Day 12.In the model substrates experiments,the degradation rates of bovine serum albumin and dextran with combination of PF and TS were 41.3%±0.1% and 48.5%±0.06%,respectively,on Day 3,which are lower than those in blank WAS(with degradation rates of 72.3%±0.5%and 90.3%±0.3%).It was revealed that the oxidative effect of PF and the solubilization of TS caused more organic matters to be dissolved out from WAS,providing a large number of biodegradable substances for subsequent SCFAs production.While WAS pretreated with the combination of PF and TS,the relative abundances of Firmicutes increased from 6.4%(blank)to 38.6%,and that of Proteobacteria decreased from 41.8%(blank)to 21.8%.The combination of PF and TS promoted the hydrolysis process of WAS by enriching Firmicutes,and then increased acetic acid production by inhibiting Proteobacteria that consumed SCFAs.Meanwhile,at the genus level,acidogenesis bacteria(e.g.,Proteiniclasticum and Petrimonas)were enriched whereas SCFAs consuming bacteria(e.g.,Dokdonella)were inhibited.

An efficient method for constructing a random insertional mutant library for forward genetics in Nannochloropsis oceanica

Insertional mutation,phenotypic evaluation,and mutated gene cloning are widely used to clone genes from scratch.Exogenous genes can be integrated into the genome during non-homologous end joining(NHEJ)of the double-strand breaks of DNA,causing insertional mutation.The random insertional mutant library constructed using this method has become a method of forward genetics for gene cloning.However,the establishment of a random insertional mutant library requires a high transformation efficiency of exogenous genes.Many microalgal species show a low transformation efficiency,making constructing random insertional mutant libraries difficult.In this study,we established a highly efficient transformation method for constructing a random insertional mutant library of Nannochloropsis oceanica,and tentatively tried to isolate its genes to prove the feasibility of the method.A gene that may control the growth rate and cell size was identified.This method will facilitate the genetic studies of N.oceanica,which should also be a reference for other microalgal species.

Multiple pretreatments can effectively improve the functionality of mesenchymal stem cells

In this editorial,we offer our perspective on the groundbreaking study entitled“Hypoxia and inflammatory factor preconditioning enhances the immunosup-pressive properties of human umbilical cord mesenchymal stem cells”,recently published in World Journal of Stem Cells.Despite over three decades of research on the clinical application of mesenchymal stem cells(MSCs),only a few therapeutic products have made it to clinical use,due to multiple preclinical and clinical challenges yet to be addressed.The study proved the hypoxia and inflammatory factor preconditioning led to higher immunosuppressive effects of MSCs without damaging their biological characteristics,which revealed the combination of inflammatory factors and hypoxic preconditioning offers a promising approach to enhance the function of MSCs.As we delve deeper into the intricacies of pretreat-ment methodologies,we anticipate a transformative shift in the landscape of MSC-based therapies,ultimately contributing to improved patient outcomes and advancing the field as a whole.

Pretreated methods on loess-palaeosol samples granulometry

Twenty representative samples were collected from the Chinese loess plateau and each sample was prepared in 6 different ways respectively in order to test the influences of pretreated methods on grain size measurement. The results show that (ⅰ) different pretreated methods can make a big difference for the samples granulometry; (ⅱ) soaking in distilled water for one day, and then treating with an ultrasonic machine for 10 min can make the sample dispersed.

Change Point Analysis to Detect the Effect of Pruning Severity on Tree Growth

The effect of pruning severity on tree growth was analyzed by change point detection using segmented regression. The present study applied this analysis to a well-known published data set including diameter growth response, tree age, pruning severity and pretreatment crown size. First, multiple regression analysis was performed to assess the effect of tree age, pruning severity and pretreatment crown size on diameter growth response. Next, segmented regression analysis was performed to assess the effect of pruning severity on diameter growth response. The results of the multiple regression showed that diameter growth response was significantly influenced by pruning severity and pretreatment crown size. The results of the segmented regression showed that in the whole data set, an abrupt change toward a decrease in diameter growth response was detected at 25% of the live crown removed. However, in the group of fully crowned and open-grown, diameter growth response continuously decreased with increasing pruning severity with no significant abrupt change, whereas in the group of 70% - 90% live crown, diameter growth response did not significantly decrease up to the break point (53% crown removed) and then abruptly decreased. This may be the first study to show the numerical evaluation of the effect of pruning severity on tree growth by change point analysis.

Biogas production from microbial-alkali pretreated corn stover by solid-state anaerobic digestion

Corn stover pretreated by Ceriporiopsis subvermispora was used as substrate to enhance biogas production via solid state anaerobic digestion(SS-AD).Effects of temperature,inoculum volume and alkaline concentration on the biogas production profermance were investigated.The results showed that pretreatment of corn stover by C.subvermispora benefited the biogas production.The optimal conditions were temperature 35°C,inoculum 10:1(w/w)and adding 5.0%of alkali,under which the maximum productions were obtained for daily and cumulative biogas of 14.07 L/kg VS and 211.09 L/kg VS.During the SS-AD process,the total solids(TS)and volatile solid(VS)were significantly degraded.The volatile fatty acids(VFA)concentration increased to 106 mmol/L and alkalinity decreased by about 23%.The results collectively suggested that microbial-alkali pretreatment of corn stove combining mesophilic condition could be a promising way to produce biogas in SS-AD.