An Overview of Recent Developments in Hetero-Catalytic Conversion of Cellulosic Biomass

In recent years, research activities involved in the production of nanocellulosic materials have grown substantially, rapidly stimulating the development of innovative production techniques. These materials are chemically extracted by acid-catalyzed Hydrolysis of the renewable and widely available cellulosic biomass. In this regard, sulfuric acid-catalyzed Hydrolysis of cellulosic biomass is a commonly known method for the production of nanostructured cellulose. However, this method may result in many disadvantages, including short catalyst-lifetime, corrosive to the reactor materials and managing the spent sulfuric acid resulted from the production process. This dictates the implementation of an eco-industrial alternative for the catalytic production of nanocrystalline cellulose (NCC). A viable and practical alternative is the application of heterogeneous (solid acids) catalysts, which can be more conducive in providing favorable platforms for efficient cellulose hydrolysis. This review highlights the current production methods of nanocrystalline cellulose. Further, recent literature on the heterogeneous-catalytic conversion of cellulosic biomass is briefly discussed. The limitations and disadvantages of these techniques are also described.

Establishment of Biological Nitrogen Removal Process for Drinking Water Treatment in Malaysia

Eutrophication arises from human activities has been recognized globally as an environmental issue. Human activities have greatly increased the input of phosphorus and nitrogen into the water bodies which place a heavy pressure on clean water resources. There are limitations in the conventional water treatment processes, where phosphorus and nitrogen could not be removed efficiently. For nitrogen removal, biological method emerges as a sustainable and economically feasible alternative in recent years. Though the biological nitrogen removal (BNR) method is widely recognized in developed countries with temperate climate, knowledge and expertise on the application of this treatment process is relatively limited in developing countries, so as Malaysia in tropical region. Thus, this research aims to provide a preliminary view on the establishment of the BNR process for drinking water treatment in the local context. A lab scale sequencing batch reactor (SBR) seeded with fish pond sludge and activated sludge in the volume ratio of 1:1 was operated for the BNR process. After four weeks of sludge cultivation, the characteristic of simultaneous nitrification-denitrification was observed. The removal of total nitrogen (TN) was found exceeding 60% and little nitrate-nitrogen (NO3̄-N) concentration was observed at the end of the process. Besides, the reduction in orthophosphate (PO43--P) concentration in a BNR system has indicated the process was able to perform nitrogen and phosphorus removal simultaneously. These findings suggest that the establishment of BNR is feasible in Malaysia.

A methodology for identifying cleaner production options to reduce carbon emission in the manufacturing industry

While industries are familiar with environmental management systems for continuous improvement of production processes and products, there are various green-concept-oriented methods that can address environmental concerns significantly. This work focused on adaptation of cleaner production strategy for enhancing environmental management systems. Specifically, this work developed self-implementable methodology that systematically leads to identification of cleaner production options to improve environmental performance and efficiency of manufacturing industry. The developed methodology aims at preventing or reducing carbon emission from production processes and activities. The proposed methodology comprises three steps. In step 1, the sources of carbon emission from the manufacturing industry are identified through materials and energy consumption and waste generation. In step 2, the fate of the sources of carbon emission is determined. The sources are to be prevented or reduced. In step 3, cleaner production options are generated. Cleaner production options include modification of key operating parameters in manufacturing processes, such as temperature, pressure and time; implementation of housekeeping practices; modification of production process; substitution of greener materials; adaptation of new technologies; training to workers and 3R (reuse, recover, recycle). The options are generated with investigative questions. A food manufacturing industry was selected as a case study to demonstrate the practicality of using the developed methodology to generate cleaner production options. A total of 15 specific cleaner production options were identified for the studied premise using the methodology proposed demonstrating the practicality of the developed methodology.

Potential Recovery of a Textile Wastewater Treatment Plant Sludge Into Clay Bricks

As the country started to become an export oriented country since the early 1970s, the growth of Malaysia’s textile industry has increased greatly. In 2011 alone, the country has provided a total of RM10.8 billion of exports of textile products and RM 6.6 billion of imports. This valuable improvement has lead to several environmental impacts involving land and water pollution. The current trend in waste management is to examine the feasibility of using textile sludge generated in wastewater treatment plants of textile industry as a partial replacement for clay as building materials. The chemical and physical properties of clay and textile have been analyzed. The effects of sludge proportion (0%-10%), and firing temperature (950oC and 1180oC) on the quality of the clay bricks were examined. The tests were conducted as per British Standard (BS) codes to investigate the potential of the textile sludge to be incorporate into clay for use as engineering blocks and load bearing bricks. According to the results, sludge addition and firing temperature are the important factors to determine the quality of clay bricks. All clay samples satisfied the requirement of British Standard norms in term of compressive strength and water absorption. It is seen that all bulk density of clay samples did not comply with good quality of clay brick but they can be categorized as lightweight building materials. Textile sludge was also tested for substitution into cement bricks. Cement samples with 10% textile sludge substitution comply with the requirement of British Standard norm for load bearing class 3. In summary, this study provides a preliminary research output that will contribute to expand a new area of research in recycling of textile sludge.

Rambutan (Nephelium lappaceum) seeds for the treatment of Palm Oil Mill Effluent (POME) and its Feedforward Artificial Neural Network (FANN) modeling

In the present research, local rambutan seed extract was used as a bio-coagulant for the treatment of palm oil mill effluent (POME). Jar test experiments were conducted to find the optimal operating conditions for the removal of turbidity and total suspended solids from POME. At an optimal pH of 3, bio-coagulant dosage of 600 mg/L and room temperature of 28⁰C, an impressive removal of 65% of total suspended solids and 79% of turbidity was achieved. Along with this, a Feedforward Artificial Neural Network (FANN) was used to model the coagulation mechanism. Three different training algorithms were tested on the FANN, namely the Lavenberg-Marquardt, Bayesian Regularization and Scaled Conjugate Gradient methods. The best training algorithm was found to be Bayesian Regularization, based on the fact that it was in closer agreement with the experiment results and gave very low error percentage. The results of this study suggest that rambutan seeds have potential in being used as a bio-coagulant for POME treatment. Treatment efficiencies were reasonably high, and less sludge was produced using this natural treatment method, thus deemed to be more economical and environmentally friendly.

Physico-mechanical properties of bio-composites fabricated from polylactic acid and rice husk treated with alkali and ionic liquid

In the present work, chemically treated rice husk (TRH) and untreated rice husk (UTRH) reinforced polylactic acid (PLA) bio-composites were produced using Haake rheomixer and compression moulding processes. Alkali (NaOH) and ionic liquid (IL: 1-ethyl-3-methylimidazolium acetate) treated rice husk samples are TRHN4 and TRHILN4 respectively. Using UTRH, TRHN4 and TRHILN4 the fabricated bio-composites are UTRH-PLA, TRHN4-PLA and TRHILN4-PLA respectively. The tensile strength (TS), tensile modulus (TM), impact strength (IS) and hardness values of TRHN4-PLA and TRHILN4-PLA were found to be much higher than the corresponding values of the UTRH-PLA bio-composites. The tensile fracture surface morphological features of TRHN4-PLA and TRHILN4-PLA composites, observed by scanning electron microscopy (SEM), revealed less micro voids and fibre agglomerates, which indicates that better filler-matrix interfacial adhesion occurred in the case of chemical treated RH compared to UTRH when blended with PLA. However, composites TRHN4-PLA and TRHILN4-PLA showed lower water uptake capacity compared to UTRH-PLA. From the FTIR spectra of UTRH, TRHN4 and TRHILN4 together with water absorption behaviour of the composite specimens, it appeared that chemical modifications significantly reduced the hydrophilic nature of RH, resulting in improved fibre-matrix interfacial adhesion. The overall physico-mechanical properties of fabricated bio-composites were found to follow this order: TRHILN4-PLA>TRHN4-PLA>UTRH-PLA.

Effect of Drum Pressure on Flow Accelerated Corrosion in Gas Fired Combined Cycle Power Plant: A Case Study and Literature Review

The dissolution of ferrous ions from the protective oxide layer and/or base metal by corrosion with the assistance of turbulent flow is called flow accelerated corrosion (FAC). Flow accelerated corrosion is the most common and continuous corrosion reaction in combined cycle power plants (CCPP). Heat recovery steam generator (HRSG) drum pressure fluctuation and/or turbulent drum water greatly influences the FAC of drum and economizer. This kind of FAC was investigated in the low-pressure drum (LPD) and low-pressure economizer (LPE) of a 210 MW gas-fired combined cycle power plant (Four-unit HRSG & GT) with an air-cooled condenser (ACC). Severe FAC was observed due to the fluctuation of pressure in the LPD with respect to time. As a result, huge amounts of soluble iron (Fe2+) and insoluble (Fe3+) was found in all running HRSG’s LPD water. Due to pressure fluctuations in the LPD, a protective oxide layer (mostly magnetite), as well as the base metal, were corroded from the LPD and LPE even after carefully maintaining recently developed water cycle chemistry in this CCPP. Severe leakage was found in the LPE due to corrosion. The actual reason for the problem was found to be a malfunctioning steam-control valve in the turbine unit’s LP system. This valve was malfunctioning by suddenly opening to 100% and then closing to around 10% continuously. This malfunction creates enormous pressure drops in both the LPD and LPE units. It is understood that water turbulence is the main cause of FAC affecting the LDP and LPE. This assessment is based on chemical laboratory analysis and physical inspection. There was no non-destructive testing (NDT) performed in this study. The severe FAC happened in four days and for this reason, HRSG and steam turbines were shut down. Maintenance work on the control valve and flushing of the LPD and LPE successfully resolved the FAC problem. One week later, LPE leakage was found on the unit-3 HRSG and as reported in this study this was also found to be the result of FAC. From this case study, it is concluded that not only water quality but also water turbulence can create severe FAC problem.

Development of IoT based Heat Exchanger Control Trainer for Undergraduate Process Control Programme

Heat exchanger control trainer is a device that helps to demonstrate process control of process variables and simulates real world industrial plant system whereas the implementation of Internet of things (IoT) technology allows wireless communication. This paper describes a work to develop an IoT based heat exchanger control trainer for undergraduate process control programme with the implement Proportional-Integral-Derivative (PID) controller and fuzzy logic controller into the control trainer system together. The work started up with the development of graphical user interface (GUI) for the control trainer followed by the construction and coding of the control trainer prototype. The work has developed a heat exchanger control trainer GUI with PID and fuzzy logic controller. Information was able to be transmitted wirelessly between the GUI and control trainer prototype using Wi-Fi modules. The tested maximum signal strength was -90 dBm in 50 m when connected to indoor Wi-Fi router. The control trainer was able to achieve simple temperature feedback control of the cold side of the heat exchanger. The user manual included the basic user guide of the developed control trainer user interface. Kp, Ki, Kd of Ziegler-Nichols tuning method obtained in Offline case studies are 90,18, 112.5 whereas 7.2009, 1.1473, and 7.3163 for Cohen-Coon tuning method. The Offline test result shows a better accuracy of control using the fuzzy logic controller with -0.07% of steady-state error. Further improvement could be made to by adding cooling system into the control trainer prototype and apply modern techniques in the GUI control systems.

Estimating Just Suspension Speed for Stirred Reactors Using Power Measurement

A simplified mathematical model was developed to predict the just suspended speed, NJS in a solid-liquid system by analyzing the net impeller power consumption to suspend solid particles. A fully baffled tank with an internal diameter of 400mm equipped with a standard Rushton turbine with a diameter of D=T/3 (133mm) was used in this work. Glass beads were used as the solid phase and distilled water was used as the liquid phase. Solid loadings were varied within the range of 0-27 wt%. Power consumption was measured using the shaft torque method. The predicted NJS values were in a good approximation to the experimental values using the Zwietering’s criterion with a deviation of 2 – 10%. The deviation was lower for higher solid concentrations.