PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 7, Number 1, 2021
to soluble COD removal close to 50% (totality of the biodegradable portion) in both reactors, but only 32% was achieved at 1.6 h HRT and 45% filling degree. Restrained wastewater-biosolids contact time rather than overload justified that, as the maximum capacity (Kincannon –Stover model, 30.6 kg sCOD/(m3 d)) wa s substantially higher than the apparent removal rates (≤ 14.1 kg sCOD/(m3 d)). The performance at 4.9 h HRT was matched at 3.2 h HRT with threefold filling ratio, which compensated the lower contact time. Higher HRT was also responsible for i) improving nutrients usage (up to 1.72 times higher sCOD/P and 1.47 sCOD/N); ii) superior suspended solids content, corresponding up to 30% of total biomass at 4.9 h, against 8.6% at 1.6 h; and iii) up to 2.45 times greater planktonic maximum specific activity. Nutrients restriction boosted the sCOD/nutrient consumption ratio up to 2.65 times for the limited nutrient and 1.70 for the abundant one, with minimal sCOD:N:P (100:0.70:0.14) at limited N and 4.9 h HRT. “Overview of Wastewater Characteristics of Cardboard Industry”, S. Harif, M.A. Aboulhassan & L. Bammou, Scientific Study & Research Chemistry & Chemical Engineering, Biotechnology, Food Industry , 22(1), 001-011, (2021). The purpose of this study is to characterize wastewater from the corrugated cardboard industry and to highlight the nature and sources of pollution. Wastewaters from the corrugator and printing processes as well as homogenization tank, which collects all effluents from industrial processes, were analysed using standard methods. The results indicate that these effluents had a significant pollution load. The wastewater from the homogenization tank had high concentration of COD (24243 ± 2374.6 mg∙L - 1), BOD5 (413.33 ±17.14 mg∙L -1) and total solids (36.84 ± 10.62 g∙L -1). In addition, the biodegradability indices were less than 0.4, indicating that the effluents from the cardboard industry are not readily biodegradable. The printing process is the main source of liquid pollution in the cardboard industry facilities. The pollution load resulting from this process was much greater than that of the corrugator process wastewater. In accordance with current standards, these industrial effluents require treatment before discharge or re-use. WOOD PANEL “ Development of surrogate predictive models for the nonlinear elasto-plastic response of medium density fibreboard-based sandwich structures ”, Yong Jie Wong, K.B. Mustapha, Yoshihisa Shimizu, Akinori Kamiya & Senthil Kumar Arumugasamy, International Journal of Lightweight Materials and Manufacture , 4(3), September 2021, 302-314. Medium-density fibreboard (MDF) belongs to a class of engineered wood products facilitating efficient use of wood wastes. For this class of materials, the development of predictive models is crucial for the simulation of their responses under mechanical loads. In this study, samples of sandwich structures based on MDF as the skins and a mushroom-based foam as the core are fabricated and tested under edgewise compression tests. Results from the tests support the idea that increasing the thickness of the skins strengthens the response of the sandwich structure against buckling failure, but also revealed that thicker skins are susceptible to complex failure modes. Towards data-driven constitutive modelling of the nonlinear elastic-plastic response of this bio-based structure, predictive models premised on feedforward backpropagation neural network (FFNN), cascade-forward backpropagation neural network (CFNN), and generalized regression neural network (GRNN) were developed. Performance of the models was assessed via error criteria that include the coefficient of determination (R 2 ), root mean squared error (RMSE) and mean absolute error (MAE). Results from the models indicate that CFNN with 15 hidden neurons under the Levenberg- Marquardt backpropagation training algorithm outperformed FFNN and GRNN models, with R 2 = 1.0, RMSE = 0.0030 and MEA = 0.0019.
Technical Abstracts
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