Removal of TOC and Color in Bleaching Effluents from Straw Pulp and Paper Mill by Fe^0-H_2O_2 Process

TOC and color in the bleaching effluent from straw pulp paper process could not reach draining standard after its treatment by a biochemical process. In this study, advanced treatment by integrated micro-electrolysis （Fe^0） method and Fenton-like process was investigated under various conditions, i.e. pH, Fe/C ratio, initial I-I2O2 concentration and carrier gas. Results showed that Fe/C ratio（V/V = 1.5）, larger H2O2 dosage around 50 rag/L, lower pH（pH= 3） turned out to be particularly efficient. Temperature was a key parameter, remarkably increasing reaction rates. Carrier air not only improved reaction efficiency, but also saved H2O2 dosage. Chlorinated organic compounds could be reductive dechlorinated by Fe^0 reaction and oxidated by OH produced from Fenton process. The combination of Fe^0 and H2O2 reactions had been proved to be highly effective for the advanced treatment of such a type of wastewaters, and important advantages concerning the application in the study.

Pulp and Paper from Sugarcane:Properties of Rind and Core Fractions

Two distinct lignocellulosic fractions(rind and core)can be obtained through a physical separation of sugarcane stalks.Although presenting differences in morphology,both fractions can be employed to produce pulps and papers.The pulps and paper sheets produced from the core and rind fractions were characterized by their chemical composition,physical properties and mechanical properties.The pulps obtained from the core presented a higher amount of fines,lower drainage ability and rendered denser and stiffer sheets.The pulps from the rind,which have a higher content of fibers and higher degree of polymerization,produced sheets with higher air permeability and water absorption.Both paper sheets presented mechanical and physical properties comparable to commercial papers and papers from different cellulosic sources.The different properties exhibited by the papers produced from each fraction allow their use for distinct purposes,and expands the opportunities in the context of sugarcane biorefinery.

Evaluating the effectiveness of using ClO_2 bleaching as substitution of traditional Cl_2 on PCDD/F reduction in a non-wood pulp and paper mill using reeds as raw materials

The effectiveness of ClO_2 bleaching as a replacement for conventional Cl_2 bleaching,which is intensively practiced in developing countries,to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in non-wood pulp and paper mills has not been field tested.The first field study was performed to investigate PCDD/F variations when ClO_2 bleaching was used as a substitute for conventional Cl_2 bleaching in a non-wood pulp and paper mill.It was found that the PCDD/F toxic equivalents(TEQs)in solid and effluent samples were approximately 1.3–14.9 times lower when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.2,3,7,8-Substituted tetrachlorinated dibenzofurans(2,3,7,8-TCDF)were the dominant contributors to total PCDD/F TEQs in samples from the investigated mill when using conventional Cl_2 bleaching.The formation amounts of 2,3,7,8-TCDF were reduced from 1.56–2.76 pg TEQ/g to 0.02–0.32 pg TEQ/g in solid samples when ClO_2 bleaching was used instead of the conventional Cl_2 bleaching.The replacement of Cl_2 with ClO_2 might decrease the chlorination reactions of dibenzofuran as potential precursors,and thus reduce the formation amounts of 2,3,7,8-TCDF.The results could provide important knowledge for suggesting the best available technique for PCDD/F reduction for non-wood pulp and paper mills in developing countries.

Enzymatic Method for Rapid Determination of Oxalic Acid in Bleaching Filtrates from the Pulp and Paper Industry

Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry. Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method. Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching fiRrates from the pulp and paper industry, The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.

Utilization of pulp and paper industrial wastewater for production of polyhydroxybutyrate by Bacillus sonorensis NAM5

Given the environmental pollution caused by petroleum-based plastics,finding alternative substitutes for sustainability has become critical.Polyhydroxybutyrate(PHB),a storage food material that is accumulated by several bacteria,is biodegrad-able,safe,environment friendly and comparable to conventional plastics.However,scale-up is an issue due to high produc-tion cost.Substrate replacement using renewable,plentiful,sustainable and low-cost carbon sources derived from industrial waste facilitates waste reduction,while also enabling the synthesis of value-added products.In this context,inexpensive pulp and paper industrial waste as carbon source was exploited for production of PHB by using previously isolated(Source:hot springs of Manikarn,Himachal Pradesh,India)thermophilic bacteria Bacillus sonorensis NAM5 under optimized conditions in a fermenter.Production was done in a fermenter under optimized conditions(72 h of incubation at 50℃temperature and 7 pH)to enhance the accumulation of PHB.The bacterial strain was able to produce 5.28±0.11 gL^(-1)after 72 h of growth without any carbon and nitrogen source supplementation to the industrial effluent.The culture accumulated 66%PHB of cell dry weight(CDW).The produced polymer was characterized through FTIR,NMR and TGA.Additionally,bacteria-treated industrial wastewater was used for phytotoxicity assay on agriculturally important crops such as wheat,maize and mung,which exhibited considerable difference in growth parameters.

Advanced lignin-acrylamide water treatment agent by pulp and paper industrial sludge: Synthesis, properties and application

A novel flocculant LA （lignin-acrylamide polymer）, which was used as aid for aluminum sulfate and polyaluminum chloride in this study, was prepared by grafting acrylamide onto lignin that deriving from pulp and papermaking sludge. Physicochemical properties of LA were measured by X-ray photoelectron spectroscopy and scanning electron microscopy. The experimental outcome indicated acrylamide was grafted onto the lignin backbone successfully. The effects of LA addition were evaluated on coagulation performance and floc characteristics as a function of aluminum （Al） dosage, such as floc size, growth rate, strength and recoverability. Effects of different dosing sequences, Al dosed first and LA dosed first, were also investigated. LA used as coagulant aid markedly enhanced the removal efficiency of turbidity and dissolved organic carbon, especially at low Al dosages. The dissolved organic carbon removal efficiencies of aluminum sulfate and polyaluminum chloride at the Al dosage range selected in this study were improved more than 30% and 5% by LA, respectively. LA dramatically enlarged floc size and it was in the order： Al dosed first 〉 LA dosed first 〉 Al. Floc strength and recoverability were also improved by LA. LA played a significant role in charge neutralization, adsorption and bridging in floc formation.

Pentachlorophenol degradation by Pseudomonas stutzeri CL7 in the secondary sludge of pulp and paper mill

A pentachlorophenol （PCP） mineralizing bacterium was isolated from the secondary sludge of pulp and paper mill and identified as Pseudomonas stutzeri strain CL7. This isolate used PCP as its sole source of carbon and energy and was capable of degrading this compound as indicated by stoichiometric release of chloride and biomass formation. P. stutzeri （CL7） was able to mineralize a high concentration of PCP （600 mg/L） than any previously reported Pseudomonad with PCP as sole carbon source. As the concentration of PCP increased from 50 to 600 mg/L, the reduction in the cell growth was observed and the PCP degradation was more than 90% in all studied concentrations. This isolate was able to remove 66.8% of PCP from the secondary sludge of pulp and paper mill when supplemented with 100 mg/L of PCP and grown for two weeks. This study showed that the removal efficiency of PCP by CL7 was found to be very effective and can be used in PCP remediation of pulp paper mill waste in the environment.

Handicraft Technique for Making Liansi Paper

Liansi paper is a kind of traditional handmade bamboo paper produced in Yanshan County,Jiangxi Province,whose handicraft technique is listed as a national intangible cultural heritage protection project.This study conducted a field survey in Shangrao,and the main survey areas included Guangxin District and the Hekou,Goose Lake,Gexian Mountain,Tianzhu Mountain,Chenfang,and Shitang townships.Field investigators communicated with a group of intangible cultural heritage inheritors,and with their assistance,clarified the steps and processes involved in the production of Liansi paper.The handicraft technique of Liansi paper consists of five steps:chopping bamboo to make bamboo filaments,steaming bamboo filaments to make bamboo pulp,interweaving fibers into wet paper,drying wet paper,and package processing.A total of 13 processes are involved:chopping bamboo,fermentation,making bamboo filaments,soaking bamboo filaments,steaming bamboo filaments,natural bleaching,pounding bamboo filaments to make bamboo pulp,stirring pulp,adding plant mucilage,interweaving bamboo fibers into wet paper,pressing paper,drying wet paper,and package processing.

Research on Carbon Peak and Carbon Neutrality Technological Pathways in the Chinese Papermaking Industry

Against the backdrop of the dual carbon goals,the papermaking industry in China faces significant pressure to reduce emissions and lower carbon intensity.Based on historical data of energy consumption in the pulp and paper industry in China from 2000 to 2020,this study analyzed the current status of paper production and energy consumption in China.Two methods were employed to predict the growth trend of paper production in China,and three carbon dioxide emission accounting methods were compared.The study used an accounting method based on the industry’s overall energy consumption and predicted the carbon dioxide(CO_(2))emissions of the Chinese papermaking industry from 2021 to 2060 under three scenarios.The study identified the timing for achieving carbon peak and proposed the measures for carbon neutrality.The results indicated that:(1)the CO_(2)emissions of the Chinese papermaking industry in 2020 were 111.98 million tons.(2)Under low-demand,high-demand,and baseline scenarios,the papermaking industry is expected to achieve carbon peak during the“14th Five-Year Plan”period.(3)In 2060,under the three scenarios,CO_(2)emissions from the papermaking industry will decrease by 11%-31%compared to the baseline year.However,there will still be emissions of 72-93 million tons,requiring reductions in fossil energy consumption at the source,increasing forestry carbon sequestration and utilization of Carbon Capture,Utilization and Storage(CCUS)technology,and taking measures such as carbon trading to achieve carbon neutrality.

Impact of shock loading with mid-stage pulping wastewater on a magnetic micro-aerobic activated sludge system

The effect of mid-stage pulping wastewater(as shock load)on micro-aerobic magnetic activated sludge system was studied.Micro-aerobic activated sludge systems with and without magnetic particles were shocked with mid-stage wastewater for 16 days.“Recovery”experiments were conducted by using simulated wastewater for 12 days.Upon the addition of mid-stage wastewater,CODCr removal pertaining to the use of magnetic particles reached 71.57%and remained above 80%in the“recovery”experiment.However,the efficiency of the reactor in the absence of magnetic particles was only 37.29%,and reached about 40%in the“recovery”experiment.After the micro-aerobic activated sludge was shocked,the flocculation performance and surface properties of the sludge were analyzed,and the results showed that all indicators of the reactors in the presence of magnetic particles were superior to those of reactors without magnetic particles.After 12 days of“recovery”,the indicators of the sludge pertaining to the reactors containing magnetic particles“recovered”completely.