Alkaline Additives Research Articles

Effect of oxalic acid and sodium hydroxide on the desulfurization of coal using UV–H2O2 oxidation system

To research the efficient and economical desulfurization of Lingshi high sulfur coal (LS), the influence of acid and alkaline additives on an ultraviolet (UV) light oxidation desulfurization system was assessed. Sodium hydroxide (NaOH) and oxalic acid (OA) were selected as the alkaline and acid additives, respectively, to investigate whether acid and alkaline additives could promote oxidative desulfurization in the UV–H2O2 system. The coal samples were investigated via scanning electron microscopy (SEM), Brannuer–Emmett–Teller analysis (BET), contact angle analysis (CA), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, the desulfurization mechanism, including sulfur removal, sulfur conversion, and change of coal surface morphology on the reaction, was investigated. The results demonstrated that the surface morphology and the pore structure in coal improved; the wettability and oxygen-containing functional groups increased after the action of NaOH and OA, which indicated that the oxidation was enhanced during the reaction. This study proved that strong oxidation promoted the efficient removal of sulfur from coal samples, where NaOH reacted strongly with pyrite, and OA influenced the removal of organic sulfur, which played a directional desulfurization effect.

Effects of climate change on metabolite accumulation in freshwater and marine cyanobacteria

Global climate change and anthropogenic nutrient inputs are responsible for increased frequency of cyanobacterial blooms that potentially contain 55 classes of bioactive metabolites. This study investigated the effects of CO2 availability and concomittant pH levels on two cyanobacteria that produce microcystins: a marine cf. Synechocystis sp. and a freshwater Microcystis aeruginosa. Cyanobacterial strains were semi-continuously cultured in mesotrophic growth media at pH 7.5, 7.8, 8.2, and 8.5 via a combination of CO2 addition and control of alkalinity. The cell concentration between treatments was not significantly different and nutrient availability was not limited. Concentration of most known cyanobacterial bioactive metabolites in both cyanobacterial strains increased as CO2 increased. At pH 7.8, bioactive metabolite intracellular concentration in M. aeruginosa and Synechocystis was 1.5 and 1.2 times greater than the other three treatments, respectively. Intracellular concentration of microginin in M. aeruginosa at pH 7.5 was reduced by 90% compared to the other three treatments. Intracellular concentration of microcyclamide-bistratamide B was lower in M. aeruginosa and higher in Synechocystis at elevated CO2 concentration. M. aeruginosa products were more diverse metabolites than Synechocystis. The diversity of accumulated metabolites in M. aeruginosa increased as CO2 increased, whereas the metabolite diversity in Synechocystis decreased as pH decreased. Overall, intracellular concentration of bioactive metabolites was higher at greater CO2 concentrations; marine and freshwater cyanobacteria had different allocation products when exposed to differing CO2 environments.

Ordered Macroporous Carbonous Frameworks Implanted with CdS Quantum Dots for Efficient Photocatalytic CO2 Reduction.

Solar-driven photocatalytic CO2 reduction is regarded as a promising way to simultaneously mitigate the energy crisis and CO2 pollution. However, achieving high efficiency of photocatalytic CO2 reduction, especially without the assistance of sacrifice reagents or extra alkaline additives, remains a critical issue. Herein, a photocatalyst of 3D ordered macroporous N-doped carbon (NC) supported CdS quantum dots (3DOM CdSQD/NC) is successfully fabricated toward photocatalytic CO2 reduction via an in situ transformation strategy. Additionally, an amines oxidation reaction is introduced to replace the H2 O oxidation process to further boost the photocatalytic CO2 reduction efficiency. Impressively, 3DOM CdSQD/NC exhibits superior activity and selectivity in photocatalytic CO2 reduction coupled with amines oxidation, affording a CO production rate as high as 5210 µmol g-1 h-1 in the absence of any sacrificial agents and alkaline additives. Moreover, 3DOM CdSQD/NC achieves an apparent quantum efficiency of 2.9% at 450 nm. Mechanism studies indicate that the 3D ordered macropores in the NC matrix are beneficial to the transfer of photogenerated carriers. Furthermore, the highly dispersed CdS QDs on the NC skeleton are able to significantly promote the adsorption of both CO2 and amine molecules and depress the CO2 activation energy barriers by stabilizing the *COOH intermediate, directly contributing to the high activity.

The benefits of autotrophic nitrogen removal from high concentration of urea wastewater through a process of urea hydrolysis and partial nitritation in sequencing batch reactor

For the sake of high efficiency and saving operational cost for high-concentration urea wastewater treatment, a novel two-stage partial nitritation (PN)-anammox process containing simultaneous urea hydrolysis and PN in sequencing batch reactor (SBR) was investigated. Although the influent urea concentration increased from 500 to 1200 mg/L, the SBR simultaneously achieved urea removal efficiency higher than 98% and stable PN with effluent NO2−-N/NH4+-N ratio of 1.0–1.3 without any extra alkalinity addition. The intracellular hydrolysis was the dominant mechanism for urea removal and persistent free ammonia inhibition on nitrite-oxidizing bacteria was the main reason for nitrite accumulation of 97.92% in SBR. The subsequent anammox reactor showed efficient nitrogen removal performance with average ammonium removal efficiency, nitrogen removal efficiency and maximum nitrogen removal loading rate of 98.08%, 81.45% and 1.05 kg N·m−3·d−1 respectively. High-throughput sequencing results indicated Gemmatimonadetes became the most abundant bacterial phylum related to potential intracellular urea hydrolysis and displayed obvious ammonium-oxidizing bacteria enrichment and nitrite-oxidizing bacteria inhibition in SBR, and the dominant anammox bacteria (Candidatus_Kuenenia) in anammox reactor. The proposed process was proven to be promising for high-concentration urea wastewater treatment, facilitating the sustainable development of the urea industry in the future.

Visual study of TiO2 nanofluid stabilization methods on inhibition of asphaltene precipitation in porous media

In situ recovery involves injection of lixiviant into an ore formation to extract a target metal. Applicability of in situ recovery is confined to deposits where adequate permeability exists. A key challenge is establishing uniform contact between the fluid and the formation in fractured environments, particularly if fractures become blocked by gypsum and other precipitates during leaching, which restricts solution flow. The degree of contact between the lixiviant and the ore is most often the critical rate-limiting factor. Prevention of asphaltene precipitation in reservoir rocks has been shown to resolve such issues in petroleum production. This research explores the potential effect of titanium dioxide (TiO2) nanoparticles in destabilizing asphaltene deposition in porous media in the presence of heptol, with a view to extend the understanding gained in this study to an in situ recovery environment. The effect of TiO2 nanofluid on incremental oil recovery was investigated using three different nanofluid stabilization methods: stabilization by ultrasound; alkaline solution addition to the nanofluid; and the application of ultraviolet radiation. The results show that the ultrasonic system is not suitable for TiO2 nanoparticle stabilization in the fluid. Alkaline addition stabilizes TiO2 nanoparticles but decrease acidic sites on the surface of the nanoparticles, which leads to lower asphaltene adsorption on TiO2 nanoparticles and a lower nanoparticle surface charge, and results in nanoparticle flocculation and instability. Ultraviolet radiation was found to be the best method for stabilizing TiO2 nanoparticles. Asphaltene adsorption did not occur at concentrations below 3000 ppm TiO2 and thus, the recovery increase using these concentrations was attributed to an increased viscosity of the injected fluid and a reduction of its interfacial tension with the host oil.

Role of oxygen and superoxide radicals in promoting H2O2 production during VUV/UV radiation of water

As a green and effective water treatment technology, vacuum UV (VUV) radiation could generate reactive species such as hydroxyl radicals (OH) and H2O2 via the homolysis and ionization of water. The formation mechanism of H2O2 in pure water was studied under irradiation of VUV/UV lamp emitting at 185 and 254 nm. The influence of dissolved oxygen was investigated. The production and the formation rate of H2O2 were promoted with enough dissolved oxygen, which demonstrated that the oxygen played an important role in H2O2 evolution. The UV254 radiation could induce the decomposing of H2O2 and had little effect on the synthesis of H2O2. Additionally, the alkaline condition and addition of some anions were unfavorable to the production of H2O2. Besides, 4-chloro-7-nitrobenzo-2-oxa-1,3-dizole (NBD-Cl) was used as the molecular probe to confirm the role of superoxide radicals (O2−/HO2) in the oxygen-containing condition. The possible formation mechanism of H2O2 was proposed. The H2O2 was produced only by the recombination of OH in the oxygen-free system, while related to O2−/HO2 besides the recombination of OH in the oxygen-containing system. This study brought new insights into the process that utilizing the in-situ generated H2O2 in VUV/UV water treatment for organic contaminants.

Designing enzyme cocktails from Penicillium and Aspergillus species for the enhanced saccharification of agro-industrial wastes

The aim of this study was to develop optimized enzyme cocktails, containing native and recombinant purified enzymes from five fungal species, for the saccharification of alkali- and acid-pretreated sugarcane bagasse (SCB), soybean hulls (SBH) and oil palm empty fruit bunches (EFB). Basic cellulases were represented by cellobiohydrolase I (CBH) and endo-glucanase II (EG) from Penicillium verruculosum and β-glucosidase (BG) from Aspergillus niger. Auxiliary enzymes were represented by endo-xylanase A (Xyl), pectin lyase (PNL) and arabinoxylanhydrolase (AXH) from Penicillium canescens, β-xylosidase (BX) from Aspergillus japonicus, endo-arabinase (ABN) from A. niger and arabinofuranosidase (Abf) from Aspergillus foetidus. Enzyme loads were 5 mg protein/g dry substrate (basic cellulases) and 1 mg/g (each auxiliary enzyme). The best choice for SCB and EFB saccharification was alkaline pretreatment and addition of Xyl + BX, AXH + BX or ABN + BX + Abf to basic cellulases. For SBH, acid pretreatment and basic cellulases combined with ABN + BX + Abf or Xyl + BX performed better than other enzyme preparations.

Features of the Electrochemical Deposition of Films from a Triple System of CoNiFe

The nature of phenomena that occurs in the electrolyte during the electrochemical deposition of CoNiFe films and the mechanism leading to the difference in the relative content of elements in the electrolyte and film was clarified. This clarification was obtained with the help of a spectrophotometric study of chloride electrolytes and the electrochemical deposition of CoNiFe films at 70 °C. An experimental study of the absorption spectra and the pH values of the FeCl2, NiCl2 and CoCl2 salt solutions at concentrations of 0.005 to 1 mol/l showed the complex nature of the ion-formation balance in single-component and mixed solutions and the dependence of ion formation on acidic and alkaline additives. The deposited CoNiFe film was made from a chloride electrolyte with a component content ratio of 1:1:1 at both high (0.5 mol/l) and low (0.006 mol\l) concentrations of each component. The content of each component in the film after the electrochemical deposition of the three component solution (FeCl2, CoCl2, and NiCl2 at equal concentrations) did not correspond to the composition of the electrolyte. The mechanism for the abnormal deposition of Co, Fe, Ni occurred due to the incomplete ionization of atoms and the differences in the mobility of ions. The magnetic susceptibility of the films formed in the triple CoNiFe system was higher than that of a permalloy. Therefore, the triple system shows promise for use in magnetic field converters.

Features of the Electrochemical Deposition of Films from a Triple System of CoNiFe

The nature of phenomena that occurs in the electrolyte during the electrochemical deposition of CoNiFe films and the mechanism leading to the difference in the relative content of elements in the electrolyte and film was clarified. This clarification was obtained with the help of a spectrophotometric study of chloride electrolytes and the electrochemical deposition of CoNiFe films at 70 °C. An experimental study of the absorption spectra and the pH values of the FeCl2, NiCl2 and CoCl2 salt solutions at concentrations of 0.005 to 1 mol/l showed the complex nature of the ion-formation balance in single-component and mixed solutions and the dependence of ion formation on acidic and alkaline additives. The deposited CoNiFe film was made from a chloride electrolyte with a component content ratio of 1:1:1 at both high (0.5 mol/l) and low (0.006 mol\l) concentrations of each component. The content of each component in the film after the electrochemical deposition of the three component solution (FeCl2, CoCl2, and NiCl2 at equal concentrations) did not correspond to the composition of the electrolyte. The mechanism for the abnormal deposition of Co, Fe, Ni occurred due to the incomplete ionization of atoms and the differences in the mobility of ions. The magnetic susceptibility of the films formed in the triple CoNiFe system was higher than that of a permalloy. Therefore, the triple system shows promise for use in magnetic field converters.

Robust Nitritation of Anaerobic Digester Centrate Using Dual Stressors and Timed Alkali Additions.

Nitrogen is commonly removed from wastewater by nitrification to nitrate followed by nitrate reduction to N2. Shortcut N removal saves energy by limiting ammonia oxidation to nitrite, but nitrite accumulation can be unstable. We hypothesized that repeated short-term exposures of ammonia-oxidizing communities to free ammonia (FA) and free nitrous acid (FNA) would stabilize nitritation by selecting against nitrite-oxidizing bacteria (NOB). Accordingly, we evaluated ammonium oxidation of anaerobic digester centrate in two bench-scale sequencing batch reactors (SBRs), seeded with the same inoculum and operated identically but with differing pH-control strategies. A single stressor SBR (SS/SBR) using pH set-point control produced HNO3, while a dual stressor SBR (DS/SBR) using timed alkalinity addition (TAA) produced HNO2 (ammonium removal efficiency of 97 ± 2%; nitrite accumulation ratio of 98 ± 1%). The TAA protocol was developed during an adaptation period with continuous pH monitoring. After adaptation, automated TAA enabled stable nitritation without set-point control. In the SS/SBR, repeatedly exposing the community to FA (8-10 h/exposure, one exposure/cycle) selected for FA-tolerant ammonia-oxidizing bacteria (Nitrosomonas sp. NM107) and NOB (Nitrobacter sp.). In the DS/SBR, repeatedly exposing the community to FA (2-4 h/exposure, three exposures/cycle) and FNA (4-6 h/exposure, two exposures/cycle) selected for FA- and FNA-resistant AOB (Nitrosomonas IWT514) and against NOB, stabilizing nitritation.

Oxidative esterification of renewable furfural on cobalt dispersed on ordered porous nitrogen-doped carbon.

A series of highly dispersed cobalt-based catalysts on N-doped ordered porous carbon (Co-NOPC) were synthesized using the sacrificial-template method. MCM-41, ZSM-5 and SBA-15 were employed as hard templates with 2,2′-bipyridine as the ligand. The physical and chemical properties of the Co-NOPC catalyst were characterized by Raman, XRD, SEM, TEM, EDX, ICP, BET, XPS. Co-NOPC had been proven to be a highly efficient catalyst for oxidative esterification of furfural (FUR) to methyl 2-furoate without alkaline additives. Catalytic performance was correlated to the dispersed cobalt, porous structure and specific surface area. The relationship between oxygen activation and the strong interaction of cobalt and pyridine nitrogen were confirmed by XPS. Catalytic performance enhancement mechanisms were correlated with the redistribution of electrons at the interface between carbon material and cobalt atoms through the molecular dynamics method and a reaction mechanism was also proposed. The optimized catalysts showed outstanding catalytic activity and stability and no obvious decrease in activity was found after 6 cycles with 99.6% FUR conversion and 96% methyl 2-furoate selectivity.

Defluidization Investigation into Bubbling Fluidized Bed Particles with Alkaline Addition during Pyrolysis

Some unwanted inorganic materials, such as alkaline compounds contained in biomass, have the potential to create slagging formations with oxide compounds from either inside or outside the bubbling fluidized bed (BFB). The process involved 88-125 µm silica sand and clay (bentonite) as bed particles during pyrolysis with KCl addition at 700°C to represent biomass under superficialN2-velocity operation. Agglomeration formation was confirmed by the decrease in the average ΔP of the experiment, which theoretically should take place during the addition of KCl, while the defluidization condition was confirmed by a consistent average ΔP particle deviation, even after further KCl additions. Investigation of 0.005 and 1 g encapsulated KCl periodical addition showed that the silica sand has a tendency to form agglomeration faster than bentonite, specifically after 0.0211 g of KCl addition (0.0032% of total silica sand mass). Meanwhile, the bentonite has a tendency to achieve defluidization formation more easily than silica sand according to deviation analysis. The ability of silica sand to maintain fluidization longer than bentonite indicates that silica sand is the better particle for this process.

Parametric investigation and optimization of passive direct ethanol alkaline fuel cells

This paper focused on the parametric investigation and optimization of passive direct ethanol alkaline fuel cells (DEAFCs). A mathematical model was developed to simulate cell performance behaviour with variations in the ethanol feed concentration, the alkaline feed concentration and the operating temperature. In addition, the crossover ethanol behaviour was examined for different operating temperatures and ethanol feed concentrations. The mathematical model was solved in Matlab Environment. The simulation results showed that the ethanol and alkaline feed concentration ratio was the key parameter affecting the cell performance. Although higher alkaline addition yielded better performance, it was not favourable for prolonged applications due to practical limitations, such as corrosion, electrode destruction and catalyst decomposition. The ethanol crossover effect was greatly affected by the operating temperature and the ethanol concentration. Higher operating temperatures and ethanol concentrations significantly increased the crossover rate and reduced the cell performance. Thus, with all of the limitations and constraints, the suggested conditions for adequate performance of passive DEAFCs systems are 4 M ethanol and 4 M OH – at T = 30 °C.

Respiração basal do solo sob três diferentes coberturas vegetais no Paraná

This study evaluated the soil basal respiration (SBR) of three forest types and seasons and their correlation with pedological attributes in the 0-5 cm land layer. Therefore, we selected two areas of commercial tree species in the central-southern Paraná region: one plot of Pinus taeda and one of Eucalyptus dunnii; and a control, a patch of native forest (Mixed Ombrophyllous Forest). We determined the SBR by the alkaline addition method, incubating the samples for seven days. We collected samples in the cool dry season (winter) and in the hot humid season (summer). Soil attributes were determined by a routine analysis (pH, K+, Ca2+, Mg2+, Al3+, P, Matéria Orgânica, areia grossa e areia fina, silte, argila e V%). We observed significant SBR differences only about summer and winter. SBR correlated significantly with organic matter. These results are similar to most of the literature. There was no difference between the forest types about the SBR, showing that even monoculture forests can present carbon fluxes statistically equal to those of an intermediate successional stage native forest. The specific edaphic fauna adapted to each ecosystem may explain the absence of this difference in relation to SBR.

Evaluation of multiple reactions in dilute benzoyl peroxide concentrations with additives using calorimetric technology

Benzoyl peroxide (BPO) is a typical organic peroxide widely used in food processing, particularly flour bleaching. Due to the unstable nature of the oxygen-oxygen bond in BPO, it readily reacts under even mid-low-temperature conditions. Lower concentrations of BPO are also potentially explosive, even when combined with acid or alkaline additives. Given the history of both potential and documented industrial accidents, this study investigates the thermal stability of various BPO concentrations when mixed with acid or alkaline solutions. In addition, differential and integral kinetic models were applied to verify that the apparent activation energy data from the differential scanning calorimetry experiments were valid. The results of autocatalysis reactions and nth-order reaction simulations presented characteristics consistent with the experimental findings. The findings in this paper can be used as a reference for BPO products that are mediated with either an acid or an alkaline solution during production, storage, transportation, or use.

High-Efficiency Reversible Hydroxide Exchange Membrane Fuel Cells

Reversible fuel cells have advantages over rechargeable batteries due to their high energy density, minimal self-discharge, and low cost. Reversible hydroxide exchange membrane fuel cells (HEMFCs) are attractive due to their ability to work with platinum-group-metal (PGM)-free catalysts. HEMFCs and hydroxide exchange membrane electrolyzers (HEMELs) have been separately studied. However, it remains a challenge to integrate the two into a single reversible cell. The major factors that limit the development of unitized reversible HEMFCs are low performance of bifunctional oxygen catalysts, hydroxide membrane stability, hydroxide ion conductivity and water management. Previous research has been focusing on electrolyte-fed HEMELs 1. However, the corrosive alkaline solution presents material compatibility problems and increases the system and balance of plant (BOP) complexity. For example, the presence of alkaline solutions can increase the complexity of the unitized reversible fuel cell system due to adding extra water purging steps during the transition between electrolyzer mode and fuel cell mode.In this study, we have developed a pure water-fed reversible HEMFC which makes it possible to use stainless steel to replace the titanium current collectors commonly used in proton exchange membrane electrolyzers (PEMELs) to reduce the manufacturing cost. We have made tremendously progress to make the HEMFC reversible without the addition of alkaline or bicarbonate electrolyte. This is the first reported reversible HEMFC with the highest round trip efficiency (RTE) at an appreciable current density (48% @ 0.5 A/cm2). The reversible test result is shown in Figure 1. In addition to the initial RTE evaluation, we also achieved promising MEA stability. However, a voltage increase was also observed in the initial stage of the durability test which is presumptively attributed to the ionomer wash-out and catalyst layer restructuring. These challenges have been addressed by innovative electrode design. Acknowledgement: The project is finacially supported by the Department of Energy's HFTO under the Grant DE-EE0008438. Reference: Abbasi, R., Setzler, B. P., Lin, S., Wang, J., Zhao, Y., Xu, H., Pivovar, B., Tian, B., Chen, X., Wu, G., Yan, Y., A Roadmap to Low‐Cost Hydrogen with Hydroxide Exchange Membrane Electrolyzers. Mater.2019, 31, 1805876 Figure 1

One-pot synthesis of azo compounds in the absence of acidic or alkaline additives

A one-pot method for the synthesis of azo compounds by the reaction of β-naphthol with aryl amines using t-BuONO as the nitrosonium source in DCM at room temperature was developed. This method features mild reaction conditions, a simple experimental procedure, and is free of acidic or alkaline additives.

Long-term operation of the pilot scale two-stage anaerobic digestion of municipal biowaste in Ho Chi Minh City

A pilot-scale two-stage anaerobic digestion system, which includes a feed tank (0.4 m3), a hydrolysis reactor (1.2 m3) followed by a methane fermenter (4.0 m3) was set up and run at the municipal solid waste landfill located in Ho Chi Minh City (HCMC), Vietnam. The feed that was separated from urban organic solid waste was collected at households and restaurants in District 1, HCMC. This study aimed to investigate the resource recovery performance of the pilot two-stage anaerobic digestion system, in terms of carbon recovery via biogas production and nutrient recovery from digestate. The average organic loading rate (OLR) of the system was step increased from 1.6 kg volatile solids (VS)·m−3·d−1, 2.5 kg VS·m−3·d−1 and 3.8 kg VS·m−3·d−1 during 400 days of operation. During the long-term operation at three OLRs, pH values and alkalinity were stable at both hydrolysis and methanogenesis stages without any addition of alkalinity for the methanogenesis phase. High buildup of propanoic acid and total volatile fatty acid concentrations in the fermenter did not drop pH values and inhibit the methanogenic process at high OLRs (2.5–3.8 kg VS m−3·d−1). The obtained total chemical oxygen demand (tCOD) removal performance was 83–87% at the OLRs ranging from 2.5 kg VS·m−3·d−1 and 3.8 kg VS·m−3·d−1, respectively. The highest biogas yield of 263 ± 64 L·kg−1 tCOD removed obtained at OLR of 2.5 kg VS·m−3·d−1. It is expected that a full scale 2S-AD plant with capacity of 5200 tons day−1 of biowaste collected currently from municipal solid waste in HCMC may create daily electricity of 552 MWh, thermal energy of 630 MWh, and recovery of 16.1 tons of NH4+-N, 11.4 tons of organic-N, and 2.1 tons of TP as both organic liquid and solid fertilizers.

Effects of high ammonia loading and in-situ short-cut nitrification in low carbon‑nitrogen ratio wastewater treatment by biocathode microbial electrochemical system

The microbial electrochemical system (MES) has great advantages in wastewater treatment for rapid chemical oxygen demand (COD) removal and low sludge yield rate. Herein, biocathode MES was proposed to remove COD from high-ammonia wastewater with low carbon‑nitrogen ratio and regulate the nitrogen forms in effluent for ANAMMOX process. The biocathode was more sensitive to ammonia nitrogen (NH4+-N) than anode and determined the power generation of MES. With COD of 500–550 mg L−1 in influent, increasing NH4+-N from 50 to 150 mg L−1 improved maximum power output (Pmax) from 3.0 ± 0.2 to 3.4 ± 0.1 W m−3, which was then reduced with further increase of NH4+-N from 300 to 600 mg L−1. However, for the cathodic reductive current, the negative effects of ammonia only revealed with NH4+-N ≥ 450 mg L−1. The cathodic equilibrium potential drop determined the power degradation, because the increased reductive compounds (NH4+ and COD) in catholyte. The high NH4+-N reduced the abundance of denitrifiers, exoelectrogens and organic-degrading bacteria on electrodes, while that of nitrogen-fixing bacteria increased. External alkalinity addition achieved in-situ short-cut nitrification and nitrite accumulation. With comparable NH4+ and NO2−, limited NO3− and low COD, the biocathode MES effluent was then suitable for subsequence ANAMMOX process.

Experimental studies of hydrothermal liquefaction of kitchen waste with H+, OH- and Fe3+ additives for bio-oil upgrading.

Kitchen waste (KW) has gradually become a prominent problem in municipal solid waste treatment. Hydrothermal liquefaction (HTL) is a promising method used to make fuel oil from food and KW. However, the upgrading of bio-oil is particularly important for the sake of industrial reuse. In this study, the KW from university restaurants was subjected to HTL experiments in order to study theoretical feasibility. With the change of conversion temperature and residence time, the optimal conversion working conditions in this study were determined according to the quality and yield of the bio-oil. Moreover, the bio-oil upgrading effects of different additives (hydrogen chloride, sodium hydroxide, and iron(III) chloride) on the HTL of KW were studied. Alkaline additives have an inhibitory effect on the bio-oil yield and positive effect on coke yield. Acidic additives and iron (Fe)-containing additives can promote bio-oil yield. As an important aspect of upgrading, the effect on the nitrogen content of bio-oil with additives was revealed. The alkaline and Fe-containing additives have little effect on reducing the viscosity of the bio-oil while with the appropriate ratio (2.5 mol•kg-1) of acidic additives to the raw material, the static and dynamic fluidity of the oil phase products are reduced to about 0.1 Pa•s.