Hydrolysis and acidification of activated sludge from a petroleum refinery

The cost-effective treatment of activated sludge that is generated by refining petroleum is a challenging industrial problem.In this study, semi-continuous stirred tank reactors(CSTRs) containing petroleum refinery excess activated sludge(PREAS)were used to comparatively investigate hydrolysis and acidification rates, after the addition of heneicosane(C_(21)H_(44))(R1)and 1-phenylnaphthalene(C16 H12)(R2) to different and individual reactors. Operation of the reactors using a sludge retention time(SRT) of 6 days and a pH of 5.0, resulted in the maintenance of stable biological activity as determined by soluble chemical oxygen demand(SCOD), volatile fatty acids(VFAs) production and oil removal efficiency. The optimum conditions for hydrogen production include a SRT of 8 days, at pH 6.5. Under these conditions, hydrogen production rates in the control containing only PREAS were 1567 mL/L(R0), compared with 1365 mL/L in Rl and 1454 mL/L-PREAS in R2.Coprothermobacter, Fervidobacterium, Caldisericum and Tepidiphilus were the dominant bacterial genera that have the potential to degrade petroleum compounds and generate VFAs. This study has shown that high concentrations of heneicosane and 1-phenylnaphthalene did not inhibit the hydrolytic acidification of PREAS.

The role and potential of attapulgite in catalytic pyrolysis of refinery waste activated sludge

Pyrolysis is a promising technology for the treatment of refinery waste activated sludge(rWAS).In this study,attapulgite as a natural clay was used to enhance the pyrolysis of rWAS.The yields,characteristics of pyrolytic products,pyrolytic kinetics and mechanisms were investigated.The attapulgite improved the conversion of rWAS into non-condensable gases and pyrolytic liquids.The bio-oil quality improved and the biochar yield reduced.The average activation energy of Stage Ⅰ(230-400℃)and Stage Ⅱ(400-500℃)decreased by 36.5%and 49.7%,respectively,compared to rWAS alone.Al_(2)O_(3)and Fe_(2)O_(3)in attapulgite enhanced the dealkylation reaction and cracking of C-C bonds.The content of the gasoline(<C_(13))fraction of bio-oil doubled relative to rWAS alone.Attapulgite promoted the deoxygenation,dehydroxylation and dehydrogenation reactions of O-containing compounds,and the content of CO and CO_(2) in non-condensable gases increased.Addition of attapulgite(rWAS:attapulgite ratio of 1:1)decreased the O mobility from 14.6%to 12.8%relative to rWAS alone.Also,the content of saturates in bio-oil increased from 38.5 wt%to 47.2 wt%and the lower heating value(LHV)increased from 6.8 kcal/kg to 8.4 kcal/kg.The heavy metals originally in rWAS were fixed into the pyrolytic residue and the environmental risks are low.This study demonstrates the role and potential of attapulgite in catalytic pyrolysis of rWAS with an added advantage of increased cost-effectiveness.

Electron transfer to direct oxidation of aqueous organics by perovskites

The residual of oxidant chemicals in advanced oxidation processes(AOPs)resulted in both economic cost and secondary pollution.Herein,we report a direct oxidation of phenolic pollutants induced by Ca-Mn-O perovskites without using an oxidant.Governed by one-electron transfer process(ETP)from the phenolics to the Ca-Mn-O perovskites,this direct oxidation proceeds in fast reaction kinetics with activation energy of 51.4 kJ/mol,which was comparable with those AOPs-based catalytic systems.Additionally,mineralization and polymerization reactions occurred on the Ca-Mn-O surface and ensured the complete removal of phenolics.The high spin state Mn(III)within Ca-Mn-O structure was the dominant active site for this ETP.The elongated axial Mn(III)–O bonds within the[MnO_(6)]octahedron facilitated the acceptance of the electrons from the phenolics and thus promoted the initiation of the direct oxidation process.Mn(III)in the high spin state can also activate dissolved O_(2)to produce singlet oxygen(^(1)O_(2))for a fast removal of phenolics.The mixed Mn(III)/Mn(IV)within Ca-Mn-O accelerated the ETP by enhancing the electrical conductivity.This efficient Ca-Mn-O-induced ETP for removal of organic contaminants casts off the dependence on external chemical and energy inputs and provides a sustainable approach for transforming the toxic organic pollutants into value-added polymers.

Biomineralized nanoparticles for the immobilization and degradation of crude oil-contaminated soil

Accidental oil leaks and spills often cause server soil pollution,and in situ remediation is a powerful and economical treatment technology.While during in situ remediation process,unpredicted migration of petroleum hydrocarbon in heterogeneous soil will lead to a long-term source of persistent aquifer contamination.To reduce the migration of petroleum hydrocarbon and effectively improve the in situ remediation efficiency,herein,fungal biomineralization strategy was proposed for the immobilization of petroleum contaminants.A ureolytic fungi strain with crude oil-degradation ability was screened and identified as Chaetomium globosum.When incubated in medium containing Ca2+and crude oil,a mineral corona with spiny nanoparticles was formed at the edge of oil and the interface characters were analyzed using fluorescent pH and dissolved oxygen(DO)sensing films,respectively.Results indicated that biominerals preferred to aggregate around the edge of crude oil,providing favorable microenvironment for fungal growth and then leading to the increase of pH in the microenvironment,eventually accompanied by the formation of mineral corona.The mineral corona with numerous nanoparticles may act as a solid and stable shell,limiting or reducing the mobility of crude oil,and providing enough time for fungal biodegradation.After 28 days incubation,oilcontaminated soil treated with fungal biomineralization showed better immobilization ability for total petroleum hydrocarbon(TPH)under simulated acid-rain condition and higher TPH removal efficiency.This is the first demonstration for the immobilization of oil through fungal biomineralized nanoparticles,thus providing a novel strategy for the in situ remediation of oilcontaminated sites.

Application of Fourier transform ion cyclotron resonance mass spectrometry in molecular characterization of dissolved organic matter

Dissolved organic matter(DOM)plays an important role in the global carbon cycle,and an in-depth analysis of its chemical composition is fundamental to the study of its environmental and biogeochemical behavior and significance.DOM is a complex mixture of organic substances,and determining its molecular composition is a long-standing challenge in the field of analytical chemistry.The development and application of Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)has enabled the identification of the chemical composition of DOM at the molecular level.This paper summarizes progress made in the molecular characterization of DOM based on the FT-ICR MS technique,including DOM sample pretreatment methods,mass spectrometry ionization techniques,data acquisition,data processing and presentation,and molecular structure characterization.Focusing on the work done by the instrument at the State Key Laboratory of Heavy Oil Processing in the China University of Petroleum,Beijing,we introduce applications of FT-ICR MS in the fields of earth science,environmental science and engineering,and look ahead to further research directions in the future.

Local bone metabolism balance regulation via double-adhesive hydrogel for fixing orthopedic implants

The effective osteointegration of orthopedic implants is a key factor for the success of orthopedic surgery.However,local metabolic imbalance around implants under osteoporosis condition could jeopardize the fixation effect.Inspired by the bone structure and the composition around implants under osteoporosis condition,alendronate(A)was grafted onto methacryloyl hyaluronic acid(H)by activating the carboxyl group of methacryloyl hyaluronic acid to be bonded to inorganic calcium phosphate on trabecular bone,which is then integrated with aminated bioactive glass(AB)modified by oxidized dextran(O)for further adhesion to organic collagen on the trabecular bone.The hybrid hydrogel could be solidified on cancellous bone in situ under UV irradiation and exhibits dual adhesion to organic collagen and inorganic apatite,promoting osteointegration of orthopedic implants,resulting in firm stabilization of the implants in cancellous bone areas.In vitro,the hydrogel was evidenced to promote osteogenic differentiation of embryonic mouse osteoblast precursor cells(MC3T3-E1)as well as inhibit the receptor activator of nuclear factor-κB ligand(RANKL)-induced osteoclast differentiation of macrophages,leading to the upregulation of osteogenic-related gene and protein expression.In a rat osteoporosis model,the bone-implant contact(BIC)of the hybrid hydrogel group increased by 2.77,which is directly linked to improved mechanical stability of the orthopedic implants.Overall,this organic-inorganic,dual-adhesive hydrogel could be a promising candidate for enhancing the stability of orthopedic implants under osteoporotic conditions.