Papers by Keyword: Paper Mill Sludge

Abstract: Paper industry produces large amounts of sludge with about 65wt% moisture content. Due to its complex composition, the charge of traditional disposal method is high and easy to bring about secondary pollution. In this paper, the influences of temperature, oxidation coefficient and residence time on the performance of supercritical water oxidation (SCWO) of paper mill sludge were investigated. The results show that SCWO can almost completely eliminate organics in sludge and obtain transparent liquid products meeting relative national standards at 550°C, 5min with an oxidation coefficient of 3.0. However, during this process, TN changes to NH₃-N, so NH₃-N in liquid products increases with operation parameters, indicating the recalcitrant nature of NH₃-N, and which needs further treatment.

Abstract: There are high organic matter and cation exchange capacity (CEC) in paper mill sludge, which can be used efficiently to amend soil properties and promote the growth of crops. The batch method was used to investigate effects of paper sludge on adsorption and desorption of Cd (II) and Pb (II) in two types paddy soil (red soil, purple soil), through adding paper sludge to red soil and purple soil. The results showed that isothermal sorption process of Cd (II) and Pb (II) by soils and paper sludge could be well described by Langmuir equation and Freundlich equation, and all coefficients (r) were higher than 0.9. The purple soil had a higher sorption capacity of Cd (II) and Pb (II) than red soil. The sorption capacities of Cd (II) and Pb (II) in soils increased after added paper sludge, and they reached adsorption equilibrium as the percentages of paper sludge were 10%, 1% in red soil and purple soil, respectively. The desorption capacities of Cd (II) and Pb (II) in soils decreased after added paper sludge, and they reached minimum as the percentages of paper sludge were 5%, 2% in red soil and purple soil, respectively. It was better to immobilize Cd (II) and Pb (II) after added paper sludge, thus paper mill sludge can relieve the migration of heavy metals in soil-crop systems. It can provide a new way for safe using of heavy metal contaminated soil and resource utilization of paper sludge.

Abstract: The combustion of paper mill sludge and bituminous coal in air was analyzed using a thermogravimetric instrument. TG and DTG curves for the blends lies between that of the individual fuels, and the main combustion characteristics of blends depended on individual fuels and followed the weighted average. As the blending ratio of paper mill sludge was increased from 10% to 90%, the ignite temperature (T_i) decreased from 529.6°C. to 275.6°C., and residual weight increased from 19.28% to 47.39%. The TG profiles of sample were almost the same at different heating rates, however there was a big difference between the DTG profiles. The maximum weight loss rate of sample increased obviously with the increment of heating rate. This work contributes to the comprehensive understanding of paper mill sludge and bituminous coal combustion and development of co-combustion technology.

Abstract: The combustion characteristics of the mixtures, which are made from different proportions of paper mill sludge and coal, were studied by the thermogravimetric analysis (TG-DTG) at different heating rates. The results showed that there were obviously three temperature zones in the paper mill sludge combustion curves, which is respectively corresponding to two devolatilization stages and a fixed carbon combustion stage. In these stages, the weight of sludge was lost promptly. When the proportions of sludge – coal blends were rather different, ignition point obviously shifted to the larger proportions, and DTG curve was more closed to the larger proportions. During the combustion process of the mixture, the paper mill sludge and the coal had basically maintained their own devolatilisation characteristics. And the comprehensive combustion characteristic index S of sludge-coal blend declined, demonstrating that higher volatility had better combustion characteristics. As the heating rate and the proportions of coal increasing, total weight loss rate increased, while burnout index C_b raised.

Abstract: The present paper reports on the results of some experiments on the progress of a previous research and describes the production, in single fast firing, of tiles containing 30 wt% of a natural red clay and a mixture of 42 wt% of paper mill sludge and 28 wt% of glass cullet which were coated with a commercial “matt white” glaze. Fired materials were characterized as a function of the top temperature (1090 or 1140 °C) reached during the fast sintering process made in an industrial roller kiln. It is observed that tiles fired at 1090 °C display the best overall performances since the matt glaze well covers the substrate concurring to maintain in line with the official standard for production the mechanical and physical properties of the tiles.

Abstract: The sintering behaviour of several ceramics prepared using a previously selected mixture of incinerated paper mill sludge and glass cullet which was blended with 10, 20, 30 and 40 wt% of some natural clayey materials has been studied. Three natural commercial product were used: a red clay, a yellow clay and a kaolin. Mixtures were blended by wet attrition milling, dried, sieved, pressed into specimens and then fired for 1 h at temperatures ranging from 1040 to 1140 °C. The resulting materials were characterized by water absorption, shrinkage and crystallographic composition. It was observed that materials containing kaolin display the best overall behaviour independently of the quantity of kaolin introduced. Conversely the optimal sintering temperature, and consequently the best properties of materials prepared using red or yellow clay was found above 1080 °C and depends of their specific composition being affected by the amount of clay added.