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BACKGROUND: Deinking is an important part of paper recycling that involves the removal of ink particles from the paper fibres. This industrial process is important so that the fibres can be recirculated back into paper production, which enables better sustainability as fewer fresh fibres are needed. In this study, we examined five different alternative fibre materials from different agricultural residues and industrial processes for the pilot production of papers. Papers containing fibres from invasive plants (Japanese knotweed), dedicated crops (miscanthus, acacia), agricultural residues (tomato stems), and industrial waste (jute - fibres from coffee bags) were printed with water-based flexo inks and deinked with two separate processes (chemical and enzymes). Mechanical (break and tensile index, breaking length) and optical properties (ISO whiteness, brightness and CIE L*a*b* values) were measured and ink elimination IR700 and deinking efficiency was calculated for the two deinking processes. RESULTS: Enzymatic treatment improved the mechanical properties of deinked pulp in comparison with the classic chemical treatment. Mechanical strength for almost all papers increased slightly (breaking length up to 20% in tomato and jute), and the optical result (brightness) increased similarly for both processes due to the bleaching action of the colour-shaded samples, whereas the deinking efficiency showed mixed results between chemical- and enzyme-type deinking (with chemical achieving better elimination measured at 700 nm) in the typical range of ink elimination values (15-35%) for flexographic inks. This indicates further optimization of the deinking with enzymes is needed due to different alternative fibre compositions and variations of residues in the delignification processes. CONCLUSION: Using a combination of adjusted enzymatic treatment as a precursor for deinking of paper-based packaging materials sourced from alternative fibres showed promising results regarding mechanical properties, whereas the optical properties need to be improved with cellulase optimization or by using mixes of different enzymes. These kinds of paper materials printed with flexo inks were found to be successfully deinkable with the chemical ISO-based deinking protocol. [ABSTRACT FROM AUTHOR]

Frequent oceanic oil spill incidents and the discharge of industrial oily wastewaters have caused serious threats to environments, food chains and human beings. Lignin wastes with many reactive groups exist as the byproducts from bioethanol and pulping processing industries, and they are either discarded as wastes or directly consumed as a fuel. To make full use of lignin wastes and simultaneously deal with oily wastewaters, porous lignin-based composites have been rationally designed and prepared. In this review, recent advances in the preparation of porous lignin-based composites are summarized in terms of aerogels, sponges, foams, papers, and membranes, respectively. Then, the mechanisms and the application of porous lignin-based adsorbents and filtration materials for oil/water separation are discussed. Finally, the challenges and perspectives of porous lignin-based composites are proposed in the field of oil/water separation. The utilization of abundant lignin wastes can replace fossil resources, and meanwhile porous lignin-based composites can be used to efficiently treat with oily wastewaters. The above utilization strategy opens an avenue to the rational design and preparation of lignin wastes with high-added value, and gives a possible solution to use lignin wastes in a sustainable and environmentally friendly way. [ABSTRACT FROM AUTHOR]

Electrocoagulation and chemical coagulation are treatment methods based on the same removal mechanism.In this study, it was investigated the effectiveness of coagulation methods using Al electrodes and Al2(SO4)3.18H2O on the wastewaters from cardboard production.In the electrocoagulation experiments, the optimum current and pH where the highest COD removal efficiency by 54% was achieved were determined respectively as 10A and 6.62.The study also it was seen that 58%COD removal was reached for the KCl concentration of 0.5 mg/L that was applied.In the chemical coagulation study, the highest removal efficiencies were obtained as 36%, 95% and 97% for respectively COD, color and turbidity.The results show that higher efficiency could be achieved by electrocoagulation as a pre-treatment step. [ABSTRACT FROM AUTHOR]

The sludge generated in the paper recycling industries presents characteristics of a fibrous mass of brown color, being classified as residue II A - no inert. Previously, most of the industries have had the landfill as the final form of disposal of this kind of waste. However, nowadays, the companies are looking for better usable alternatives for those residues, as the treatment for using the residues as inputs in other processes and products, with the intention to avoid or to reduce environmental liabilities. In this context, the aim of the present work was the study of a biological treatment for the paper recycling sludge, through the construction, operation and monitoring of windrow composting. Due to the intrinsic characteristics of the sludge, as low C/N ratio and high content of nitrogen, it had been necessary to add residue of pruning and weeding and sugarcane bagasse in the experiments to reach appropriate values for the composting. At the end of the experiment, the residue of pruning and weeding with sludge composting, generated an organic compost, potentially usable as a fertilizer, which complies to the established values for the Ministry of Agriculture, instituted by the Instruction Normative n° 25 of 23/07/2009. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this research was to develop an alkali pretreatment process prior to anaerobic digestion (AD) of pulp and paper sludge (PPS) to improve the methane productivity. Different concentrations of sodium hydroxide solution were used to pretreat PPS, and then followed by AD of PPS and monosodium glutamate waste liquor (MGWL). Laboratory-scale experiments were carried out in completely mixed bioreactors, 1L capacity with 700mL worked. Optimal amount of sodium hydroxide for organics solubilization in the step of pretreatment was 8g NaOH/100g TSsludge. Under this condition, the PPS flocs structure was well disrupted resulting in the void rate and fiber size decreased after pretreatment, and SCOD increased up to 83% as well as the peak value of VFA concentration attained 1040mgaceticacid/L during AD. The AD efficiency of PPS with and without pretreatment was evaluated. The highest methane yield under optimal pretreatment condition was 0.32m3 CH4/kgVSremoval, 183.5% of the control. The results indicated that alkali/NaOH pretreatment could be an effective method for improving methane yield with PPS. [Copyright &y& Elsevier]

Since the early 1980s, anaerobic treatment of industrial effluents has found widespread application in the pulp and paper industry. Over 200 installations are treating a large variety of different pulp and paper mill effluents. Amongst various anaerobic systems the UASB and IC are the most applied anaerobic reactor systems. Anaerobic treatment is well feasible for effluents originated from recycle paper mills, mechanical pulping (peroxide bleached), semi-chemical pulping and sulphite and kraft evaporator condensates. The advantages of anaerobic pre-treatment are (1) net production of renewable energy (biogas), (2) minimized bio-solids production, (3) minimal footprint and (4) reduced emission of greenhouse gases. Via in-line application of anaerobic treatment in closed circuits (paper kidney technology) further savings on cost of fresh water intake and effluent discharge levies are generated. [ABSTRACT FROM AUTHOR]

Purification of wastewater from paper factory was attempted by superconducting high gradient magnetic separation (HGMS) both in laboratory scale and pilot-plant scale experiments. Magnetite and some kinds of iron hydroxide particles were used as scavenging materials for suspended substances (SS) and organic dye molecules included in wastewater. The chemical oxygen demand (COD value) was used as a measure of purification of the wastewater. Optimum dosage of the scavenger was examined. Model wastewater was also prepared and tested in order to elucidate the mechanism of adsorption of the organic materials onto the scavenging particles. The obtained results showed that the wastewater was successfully purified by HGMS both in a laboratory scale and a pilot-plant scale. The apparatus modifications of magnetic filters and flow path were also made to accomplish the purification system for the practical use. The results can allow us to promote a scale-up design for greater capacity of the treatment of wastewater. [ABSTRACT FROM AUTHOR]