Paper sludge as a feasible soil amendment for the immobilization of Pb^(2+)

The possibility of amending Pb 2＋ contaminated soil （S） with paper sludge （P） was investigated through adsorption and desorption experiments. The adsorption process of Pb 2＋ in soil containing paper sludge （SP） could be well described by pseudo second-order kinetic model and the Langmuir isotherm model. After P addition, the equilibrium time decreased greatly （from 28 to 8 hr） and the Pb 2＋ maximum adsorbed amount （Q max ） increased by a factor of more than three to 102.04 mg/g. Q max reached its maximum as S：P was 9：1 （m/m） after 10 days contact between S and P. Moreover, Pb 2＋ adsorbed amount increased with the rise of pH during the adsorption process. Desorption experiments indicated that Pb 2＋ adsorption in SP was irreversible. The metal ion fraction was analyzed with Energy Dispersive Spectrometer and Environmental Scan Electron Microscope. As a result, the addition of P to soil was found to induce a decrease in the mobile forms. The Pb 2＋ complexes formation in the presence of carbonates was the main adsorption mechanism. Overall, the paper sludge could be one of the promising soil amendments for the remediation of soil with Pb 2＋ contamination.

Material conversion from paper sludge ash in NaOH solution to synthesize adsorbent for removal of Pb^(2+),NH_4^+and PO_4^(3-) from aqueous solution

Material conversion from paper sludge ash （PSA） in NaOH solution was attempted to synthesize the adsorbent for removal of inorganic pollutants, such as Pb^2＋, NH^4＋ and PO4^3- from aqueous solution. PSA of 0.5 g was added into 10 mL of 3 mol/L NaOH solution, and then heated at 80, 120, and 160℃ for 6-48 hr to obtain the product. PSA mainly composed of two crystalline phases, gehlenite （Ca2Al2SiO7） and anorthite （CaAl2Si2O8）, and amorphous phase. Hydroxysodalite （Na6Al6Si6O24-8H2O） was formed at 80℃, and anorthite dissolved, whereas gehlenite remained unaffected. Katoite （Ca3Al2SiO4（OH）8） was formed over 120℃, and hydroxycancrinite （Nas（OH）2Al6Si6O24·2H2O） was formed at 160℃, due to the dissolution of both gehlenite and anorthite. Specific surface areas of the products were almost same and were higher than that of raw ash. Cation exchange capacities （CECs） of the products were also higher than that of raw ash, and CEC obtained at lower temperature was higher. Removal abilities of products for Pb^2＋, NH4＋, and PO4^3- were higher than that of raw ash. With increasing reaction temperature, the removal efficiencies of Pb^2＋ and NH4＋ decreased due to the decrease of CEC of the product, while removal efficiency for PO4^3- was almost same. The concentrations of Si and AI in the solution and the crystalline phases in the solid during the reaction explain the formation of the product phases at each temperature.

Photodegradation of Orange Ⅱ using waste paper sludge-derived heterogeneous catalyst in the presence of oxalate under ultraviolet light emitting diode irradiation

A waste paper sludge-derived heterogeneous catalyst（WPS-Fe-350） was synthesized via a facile method and successfully applied for the degradation of Orange Ⅱ in the presence of oxalic acid under the illumination of ultraviolet light emitting diode（UV-LED） Powder X-ray diffraction,Fourier-transform infrared spectroscopy,scanning electronic microscopy and N2 sorption isotherm analysis indicated the formation of α-Fe2O3 in the mesoporous nanocomposite.The degradation test showed that WPS-Fe-350 exhibited rapid Orange Ⅱ（OⅡ） degradation and mineralization in the presence of oxalic acid under the illumination of UV-LED.The effects of p H,oxalic acid concentration and dosage of the catalyst on the degradation of OⅡ were evaluated,respectively.Under the optimal conditions（1 g/L catalyst dosage,2 mmol/L oxalic acid and p H 3.0）,the degradation percentage for a solution containing 30 mg/L OⅡ reached 83.4% under illumination by UV-LED for 80 min.Moreover,five cyclic tests for OⅡ degradation suggested that WPS-Fe-350 exhibited excellent stability of catalytic activity.Hence,this study provides an alternative environmentally friendly way to reuse waste paper sludge and an effective and economically viable method for degradation of azo dyes and other refractory organic pollutants in water.

Effects of Paper Mill Sludge on Potassium, Sodium, Calcium, and Magnesium Concentrations in Different Soybean Cultivars

A field experiment was conducted on a sandy loam soil at an Experimental Farm in Taejon, South Korea, to determine the effects of paper mill sludge compost application rates on K, Na, Ca and Mg concentrations of soybean (Glycine max (L.) Merr.) aboveground tissues and the genotypic effects on the concentrations of these elements. Sludge compost treatments of 0, 75, and 150 t ha-1 were applied to 30 diverse soybean cultivars. Concentrations of K, Na, Ca, and Mg in aboveground tissues harvested 69 days after …

Properties of paper mill sludge–wood fiber–HDPE composites after exposure to xenon-arc weathering

We used paper mill sludge（PMS） to substitute for part of the wood fibers（WF） used to reinforce high density polyethylene（HDPE）.The resulting composites were subjected to xenon-arc weathering.The composite filled with limited PMS（under 10 %） had mechanical properties and aging resistance similar to those without PMS.The composites containing more PMS faded and cracked more readily than those without PMS.Based on the carbonyl index,crystallinity,and wood index,PMS appeared to accelerate the degradation of composites during weathering.Adding PMS to WF–HDPE composites reduced the weathering resistance,and this reduction was not significant if the PMS content did not exceed 20 % of the wood fibers.Therefore,PMS could be used as a reinforcement in wood-plastic composites at levels less than20 % of the wood fiber content.

Aerobic composting of paper mill sludge and the reuse of compost in agriculture

Paper mill sludge （PMS） is a kind of bio-solid waste. The technology of aerobic composting of PMS was investigated. The ratio of the material components was as follows, sludge：chicken dung：spill=6kg：2kg：4kg, which could attain 55% moisture content （MC） and 25 the ration of carbon to nitrogen （C/N）. The aeration rule of fan was controlled by single chip microcomputer （SCM）. During composting, the system temperature more than 55℃ lasted for 3 days, pH changed in the range of 6.5-8.5 and MC changed between 53% to 60%. PMS became mature on the 20th day. The germination index （GI） of compost attained 95% or so and coliform was 23/100 ml volatile solid （VS） and organic carbon （OC） were stable at the content of 60% and 30%, respectively. The result showed that this technology could make the sludge stable and innocuous. A pot experiment with latosolic red soil mixed with paper mill sludge compost （PMSC） was carried on. The result showed that PMSC could increase the crop biomass, the soil nutrients and the physical characteristics of the soil, such as OC, total nitrogen （TN）, total phosphorus （TP）. The total amount of heavy metals in the soil was measured to be lower than the Environmental standard for soil in China （GB15618-1995）. So PMSC was a good and safe soil amendment.

Effects of amendments of paper mill sludge and nutrients on soil surface CO2 flux in northern hardwood forests

Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs） in northern hardwood forests and to quantify the relationship among Rs, soil temperature, and moisture in these stands. The experiment was a randomized complete block design that included sludge-amended, fertilized, and control treatments in sugar maple （Acer saccharum Marsh） dominated hardwood forests in the Upper Peninsula of Michigan, USA. Results showed that Rs was positively correlated to soil temperature （R^2 = 0.80, p 〈 0.001）, but was poorly correlated to soil moisture. Soil moisture positively affected the Rs only in the sludge-amended treatment. The Rs was significantly greater in the sludge-amended treatment than in the fertilized （p = 0.033） and the control （p = 0.048） treatments. The maximum Rs in the sludge-amended treatment was 8.8 μmol CO2 · m^ 2. s^-1, 91% and 126% greater than those in the fertilized （4.6 μmol CO2 · m^-2· s^-1） and control （3.9 μmol CO2· m^- 2· s^-1） treatments, respectively. The Rs did not differ significantly between the fertilized and control treatments. The difference in Rs between sludge-amended and the other treatments decreased with time following treatment.

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.

Fenton-like degradation of Methylene Blue using paper mill sludge-derived magnetically separable heterogeneous catalyst:Characterization and mechanism

For the paper industry, the disposal and management of the yielded sludge are a considerable challenge. In our work, the paper mill sludge-derived magnetically separable heterogeneous catalyst（PMS-Fe-380） was prepared easily through a facile synthesis method. The morphology and structure of PMS-Fe-380 were fully characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmet–Teller analysis. The catalytic activity of PMS-Fe-380 was evaluated by degradation of Methylene Blue（MB）. The reusability and stability of PMS-Fe-380 were evaluated in five repeated runs, which suggested that PMS-Fe-380 manifested excellent stability of catalytic activity. Moreover,leaching tests indicated that the leached iron is negligible（〈0.5 mg/L）. This study provides an alternative environmentally friendly reuse method for paper mill sludge and a novel catalyst PMS-Fe-380 that can be considered as a promising heterogeneous Fenton-like catalyst.

Emission and drying kinetics of paper mill sludge during contact drying process

The emission and contact drying kinetics of the paper mill sludge (PMS) were studied through experiments carried out in a paddle dryer. To get a better understanding of its drying mechanism, a penetration model developed by Tsotsas and Schlünder (1986) was used to simulate the drying kinetics of the PMS. The result indicated that this kinetics could be divided into three phases: pasty, lumpy and granular phases, and could be successfully simulated by the penetration model as the related sludge parameters were integrated into the model. The emission rate curves of the volatile compounds (VCs) were interrelated to the drying rate curve of the PMS, especially for volatile fatty acids (VFAs) and ammonia in this study.