Phaik Eong Poh

Extraction agents for the removal of polycyclic aromatic hydrocarbons (PAHs) from soil in soil washing technologies.

Polycyclic aromatic hydrocarbons (PAHs) in soil have been recognised as a serious health and environmental issue due to their carcinogenic, mutagenic and teratogenic properties. One of the commonly employed soil remediation techniques to clean up such contamination is soil washing or solvent extraction. The main factor which governs the efficiency of this process is the solubility of PAHs in the extraction agent. Past field-scale soil washing treatments for PAH-contaminated soil have mainly employed organic solvents or water which is either toxic and costly or inefficient in removing higher molecular weight PAHs. Thus, the present article aims to provide a review and discussion of the alternative extraction agents that have been studied, including surfactants, biosurfactants, microemulsions, natural surfactants, cyclodextrins, vegetable oil and solution with solid phase particles. These extraction agents have been found to remove PAHs from soil at percentages ranging from 47 to 100% for various PAHs.

A comprehensive guide of remediation technologies for oil contaminated soil — Present works and future directions

UNLABELLED Oil spills result in negative impacts on the environment, economy and society. Due to tidal and waves actions, the oil spillage affects the shorelines by adhering to the soil, making it difficult for immediate cleaning of the soil. As shoreline clean-up is the most costly component of a response operation, there is a need for effective oil remediation technologies. This paper provides a review on the remediation technologies for soil contaminated with various types of oil, including diesel, crude oil, petroleum, lubricating oil, bitumen and bunker oil. The methods discussed include solvent extraction, bioremediation, phytoremediation, chemical oxidation, electrokinetic remediation, thermal technologies, ultrasonication, flotation and integrated remediation technologies. Each of these technologies was discussed, and associated with their advantages, disadvantages, advancements and future work in detail. Nonetheless, it is important to note that no single remediation technology is considered the best solution for the remediation of oil contaminated soil. CAPSULE This review provides a comprehensive literature on the various remediation technologies studied in the removal of different oil types from soil.

Bathroom greywater recycling using polyelectrolyte-complex bilayer membrane: Advanced study of membrane structure and treatment efficiency.

Polyelectrolyte-complex bilayer membrane (PCBM) was fabricated using biodegradable chitosan and alginate polymers for subsequent application in the treatment of bathroom greywater. In this study, the properties of PCBMs were studied and it was found that the formation of polyelectrolyte network reduced the molecular weight cut-off (MWCO) from 242kDa in chitosan membrane to 2.71kDa in PCBM. The decrease in MWCO of PCBM results in better greywater treatment efficiency, subsequently demonstrated in a greywater filtration study where treated greywater effluent met the household reclaimed water standard of <2 NTU turbidity and <30ppm total suspended solids (TSS). In addition, a further 20% improvement in chemical oxygen demand (COD) removal was achieved as compared to a single layer chitosan membrane. Results from this study show that the biodegradable PCBM is a potential membrane material in producing clean treated greywater for non-potable applications.

Current Advances of Biogas Production via Anaerobic Digestion of Industrial Wastewater

Following the increasing energy demand due to rapid industrialization and anthropogenic carbon dioxide (CO2) emission from fossil fuel consumption, there is a need to identify a replacement of non-renewable sources for power generation to control the CO2 emission to the atmosphere. Though there are many renewable energy options available, these renewable sources have their limitations. Biogas production from anaerobic digestion (AD) can be a viable source of renewable energy especially when the feedstock for anaerobic digestion is taken from wastes generated by various industries. Treatment of these wastes not only reduces the environmental impact but also continuously generate renewable energy that could reduce the reliance of power consumption of an industry from the grid. This chapter provides an overview of AD process, current practices of AD of industrial wastewater and methods that could further improve biogas production from AD.

Optimization of Wastewater Anaerobic Digestion Using Mechanistic and Meta-heuristic Methods: Current Limitations and Future Opportunities

Anaerobic digestion is widely used to treat high-strength wastewater and produces methane as a by-product for power generation. Treatment and reuse of industrial effluent also contribute to water conservation efforts. Nevertheless, the sensitivity of anaerobic digestion system proves to be a challenge in ensuring consistent quality of treated wastewater and biogas production. Hence, it is essential to devise an effective model and control system that accurately represent the dynamics of anaerobic digestion and can respond to changes in process parameters with proper fault detection and output prediction. This article provides a comprehensive review on (1) the anaerobic digester technology and parameters governing its efficiency, (2) mechanistic and meta-heuristic models used to describe this process, and (3) the process control strategies. In this study, adaptive controller was found to be able to provide wider options in terms of controlled and manipulated variables. Nevertheless, an in-depth study is essential to determine the best controller to be applied for a particular system where further optimization can be done to achieve the best performance.

Fuzzy logic modelling for thermophilic anaerobic digestion of palm oil mill effluent (POME) treatment

Treatment of POME has become more challenging with stringent effluent discharge standards and difficulty of current treatment processes to meet the standards due to the complex nature of POME. Utilization of high-rate anaerobic reactor operated under thermophilic condition is proposed for primary POME treatment due to low energy requirements and biogas production that could generate revenue to the industry. However, successful implementation of such system is dependent on the availability of a well-defined model. Hence, fuzzy inference method was employed to model the thermophilic anaerobic digestion of POME. Fuzzy Inference Model (FIM) which utilizes historical data of the reactor condition and digestion performance showed worthy estimation, with an average error and standard deviation of 2.81% and 2.10%; 10.35% and 8.67%; 12.22% and 10.40% for pH, COD and TSS correspondingly.