Reduction of Colour from effluents of Pulp and Paper Industry by Ozonation: A Review

Pulp and paper making is the major old process industry in India which is water intensive and generates heavy water pollution. Pulp and paper industries are the fifth largest contributor to industrial water pollution. Waste water is generated from each and every section of paper making process and depends upon the type of pulping and bleaching process. Presently, primary and secondary (Biological) treatment systems based on activated sludge process are widely used by paper industry for effluent treatment. The process requires high energy and chemical inputs and involves high operational costs. One of the novel processes for treating effluent is its oxidation through ozonation which is a greener way of degrading pollutants. Ozonation of intermediate stage effluents having high colour load is more effective for industrial application and re-utilization.

Evaluation of pulp and paper making properties of Caesalpinia decapetela

The world demand for paper has been increased due to the increasing population Therefore, to cop up the limited wood fiber resources introducing raw material in pulp and paper industries is necessary. The aims of this study to evaluate the pulp and paper-making properties of Caesalpinia decapetela based on proximate chemical composition, fiber morphology, pulping, bleaching, and physical test of the final product. The results proximate chemical analysis showed that C. decapetela has holocellulose content of 78.14±0.1 % and lignin content 18.0±0.04 %. Fiber morphology revealed that the fibers were 0.708 mm long, 18.63 μm width, and have 5.1 μm cell wall thicknesses. Kraft pulping of C. decapetale, was performed at different active alkali (5 %, 10 %, 15 %, 20 % and 25 %) and temperature (150, 160 and 170 °C), keeping the sulphidity 25 % constant. The pulp maximum yield 44.1 % was obtained at active alkali content of 15 %, temperature 160 °C, and cooking time 90 minutes. The effect of pulping on fiber morphology was studied using scanning electron microscopy which showed the surface of fiber before pulping was tight, orderly arranged and the texture was relatively hard. After pulping, there was the removal of lignin, hemicellulose, and cellulose. Due to this fiber become soft loosened and contain micro-pores. Pulp produced was bleached, sheet preparation and testing were performed. The prepared paper sheets have a tensile index of 28.19 Nm/gm, burst index of 1.359 kPa m 2 / gm 1.359\hspace{0.1667em}\text{kPa}\hspace{0.1667em}{\text{m}^{2}}/\text{gm} , and tear indices of 4.2 mN m 2 / gm 4.2\hspace{0.1667em}\text{mN}\hspace{0.1667em}{\text{m}^{2}}/\text{gm} . This study concluded C. decapetale can be the new raw material for pulp and paper making industries. However, pilot plant studies are required to check this raw material for the full recommendation of the pulp and paper industries.

Chemical content and fiber dimension of agarwood branches (Aquilaria malaccensis Lamk)

Potential utilization of agarwood residues from twigs and branches is supported by its chemical content and fiber quality. This study aimed to analyze the chemical content and fiber quality of agarwood branches (Aquilaria malaccensis Lamk). Parameters measured in this study were the chemical contents including extractives, holocellulose, alpha cellulose and lignin based on Technical Association of Pulp and Paper Industries (TAPPI) standard. Fibers were obtained after pulping and bleaching to determine its quality. Chemical analysis of the primary branch of agarwood revealed the composition of extractives which were soluble in cold water (2.71%), hot water (3.31%), ethanol benzene (3.81%), and 1% NaOH (10.03%). The proportion of holocellulose, alpha cellulose and lignin in the primary branch was 78.17%, 52.70% and 26.68%, respectively. In addition, the chemical analysis of the secondary branch of agarwood also revealed the soluble extractives in cold water (2.96%), hot water (3.49%), ethanol benzene (4.14%), and 1% NaOH (14.42%). The proportion of holocellulose, alpha cellulose and lignin in the secondary branch was 75.61%, 50.65% and 26.77%. Hence, the fiber quality of agarwood branches was categorized into class II.

Added-Value Chemicals from Lignin Oxidation

Lignin is the second most abundant component, next to cellulose, in lignocellulosic biomass. Large amounts of this polymer are produced annually in the pulp and paper industries as a coproduct from the cooking process—most of it burned as fuel for energy. Strategies regarding lignin valorization have attracted significant attention over the recent decades due to lignin’s aromatic structure. Oxidative depolymerization allows converting lignin into added-value compounds, as phenolic monomers and/or dicarboxylic acids, which could be an excellent alternative to aromatic petrochemicals. However, the major challenge is to enhance the reactivity and selectivity of the lignin structure towards depolymerization and prevent condensation reactions. This review includes a comprehensive overview of the main contributions of lignin valorization through oxidative depolymerization to produce added-value compounds (vanillin and syringaldehyde) that have been developed over the recent decades in the LSRE group. An evaluation of the valuable products obtained from oxidation in an alkaline medium with oxygen of lignins and liquors from different sources and delignification processes is also provided. A review of C4 dicarboxylic acids obtained from lignin oxidation is also included, emphasizing catalytic conversion by O2 or H2O2 oxidation.

Utilization of Organic Mixed Biosludge from Pulp and Paper Industries and Green Waste as Carbon Sources in Blast Furnace Hot Metal Production

A six day industrial trial using hydrochar as part of the carbon source for hot metal production was performed in a production blast furnace (BF). The hydrochar came from two types of feedstocks, namely an organic mixed biosludge generated from pulp and paper production and an organic green waste residue. These sludges and residues were upgraded to hydrochar in the form of pellets by using a hydrothermal carbonization (HTC) technology. Then, the hydrochar pellets were pressed into briquettes together with commonly used briquetting material (in-plant fines such as fines from pellets and scraps, dust, etc. generated from the steel plant) and the briquettes were top charged into the blast furnace. In total, 418 tons of hydrochar briquettes were produced. The aim of the trials was to investigate the stability and productivity of the blast furnace during charging of these experimental briquettes. The results show that briquettes containing hydrochar from pulp and paper industries waste and green waste can partially be used for charging in blast furnaces together with conventional briquettes. Most of the technological parameters of the BF process, such as the production rate of hot metal (<1.5% difference between reference days and trial days), amount of dust, fuel rate and amount of injected coal, amount of slag, as well as contents of FeO in slag and %C, %S and %P in the hot metal in the experimental trials were very similar compared to those in the reference periods (two days before and two days after the trials) without using these experimental charge materials. Thus, it was proven that hydrochar derived from various types of organic residues could be used for metallurgical applications. While in this trial campaign only small amounts of hydrochar were used, nevertheless, these positive results support our efforts to perform more in-depth investigations in this direction in the future.

Neutralization of Acidic Wastewater from a Steel Plant by Using CaO-Containing Waste Materials from Pulp and Paper Industries

In this study, CaO-containing wastes from pulp and paper industries such as fly ash (FA) and calcined lime mud (LM) were utilized to neutralize and purify acidic wastewaters from the pickling processes in steel mills. The investigations were conducted by laboratory scale trials using four different batches of wastewaters and additions of two types of CaO-containing waste materials. Primary lime (PL), which is usually used for the neutralization, was also tested in the same experimental set up in the sake of comparison. The results show that these secondary lime sources can effectively increase the pH of the acidic wastewaters as good as the commonly used primary lime. Therefore, these secondary lime sources could be potential candidates for application in neutralization processes of industrial acidic wastewater treatment. Moreover, concentrations of metals (such as Cr, Fe, Ni, Mo and Zn) can decrease dramatically after neutralization by using secondary lime. The LM has a purification effect from the given metals, similar to the PL. Application of fly ash and calcined lime mud as neutralizing agents can reduce the amount of waste from pulp and paper mills sent to landfill and decrease the need for nature lime materials in the steel industry.