Frontiers in Water and Environment

Biodegradation of Pyrene by Using Earthworm in Soil

Rubiyatno — 2024-11-27

Pyrene, a toxic four benzene ring Polycyclic Aromatic Hydrocarbons (PAHs) that persists in the environment, is highly resistant to degradation. Therefore, this study aims are to investigate the mechanism and optimum pyrene degradation rate with minimum toxic by-products by using earthworms. The earthworms were collected randomly from soil at Universiti Teknologi Malaysia (Malaysia) as pyrene degrader to eliminate pyrene in soil. Several factor such as soil to earthworm ratio, soil moisture content, effect of soil sterilization and comparison of pyrene degradation using different experimental approaches on pyrene degradation efficiency were examined. In this study was found by using earthworms, 25% of pyrene was removed by earthworms from 200 g of soil containing 100 mg L^-1 of pyrene after 14 days treatment, suggesting that wild earthworms were able to degrade the pyrene with higher efficiency in the natural soil without sterilization. However, no metabolite was detected during the pyrene removal process. The pyrene might be fully degraded or accumulated in fatty tissue in earthworms. Nevertheless, in the treatment using wild earthworms are suitable to be used as pyrene degrader.

Potential Use of Rise Husk as Filler in Poly Lactic Acid Bio-composite: Mechanical Properties, Morphology and Biodegradability

Martin Hii Chun Yeong — 2024-11-27

About 408,000 metric tonnes of rice husk are produced annually yet not utilised fully. In agriculture, biodegradable plastics are desirable alternative to the current black low densities poly(ethylene) plastic. Therefore, a research on bio-polybag is needed to be investigated their properties of obtained polybag in terms of mechanical properties, surface structure, and biodegradability. The biomasses studied in this research are rice husk (RH) due to their abundance in Malaysia, and polylactic acid were used to mix with the biomasses in different compositions (10%, 30%, 50%, 70% and 90%). Three main tests including tensile strength test, aging test and Scanning Election Microscopy (SEM) were taken place to study the properties. As a result, 30% rice husk: 70% PLA is the best among the ratio, in terms of lower tensile strength, higher elasticity, and shows bigger void and gap. At ratio of 30% rice husk and 70% PLA has the tensile strength of 11.3 MPa, tensile modulus at 322.12 MPa, elongation at break at 3.508%, decomposition rate of 3.3% and SEM analysis showed many gaps yet with maximum used of biomass material. Hence, ratio of 30% rice husk and 70% PLA is the most suitable biomass to use as biodegradable polybag.

Potential Co-Culture of Fungi in Degradation of 1,4-Dioxane

Ajeng Arum Sari — 2024-11-27

Biodegradation using fungi become a concern for a decade to remove pollutants, it is due to cost-effectiveness, inherent eco-friendly properties, and potential for complete decomposition of harmful compounds. A single strain of fungi was studied to degrade various pollutants has been commonly investigated. However, the degradation of 1,4-Dioxane by co-culture white-rot fungi has not been investigated. Dioxane contamination is known as public health due to its adverse health effect, including carcinogens and persistence in the natural water system. Therefore, this study has aimed to investigate the degradation of 1,4-Dioxane and compared it with the addition of inducer. Co-culture of fungi (Trametes versicolor F200 and Pestalotiopsis sp. NG007) can improve degradation of 1,4-Dioxane after the addition of inducers. It degraded dioxane 71% at 50 ppm and 47% at 500 ppm for 60 days. MnSO₄ as an inducer was capable to enhance the activity of enzymes and degradation rate.

Possible Impacts of Exogenous Pollutants Occurring in Waste Activated Sludge during Anaerobic Digestion

Wei Sheng Choong — 2024-11-27

Anaerobic digestion is considered as a biological procedure as the metabolisms included in the digestion process of waste activated sludge are easily affected by distinct operating conditions. This study investgates the impact of regularly distinguishable pollutants with high concentrations in waste activated sludge such as nanoparticles, pharmaceutical products and heavy metals on the execution of waste activated sludge digestion. Different types of exogenous pollutants showed different effects on the sludge methanogenesis and acidification processes, hydrolysis and solubilization as well as the correlating concentrations. It was also observed that the majority of the pollutants observed in the waste activated sludge would normally react towards anaerobic digestion at low levels but exhibit obvious negative impacts at high dosages.

Overview of Clinical Waste Management in Malaysia

Thien Choi Yi — 2024-11-27

Clinical waste management system in Malaysia was established in 1980 after the emergence of HIV. Ministry of Health of Malaysia and the Department of Environment Malaysia have revised the current policies and guidelines to control infectious disease and handling clinical waste. The clinical waste management services are managed by private consortiums under the supervision of the government according to the Scheduled Waste Regulation 2005. The disposal method through incineration process turns the clinical waste into ash and disposed of at the approved landfill site. Malaysia also practicing recycling and recovery of non-infectious clinical waste to reduce the cost and minimize waste generation. However, clinical waste management became an issue due to the outbreak of COVID-19 in December 2019 posing a serious impact on all parts of society. The waste generated sharply increased with the quantity demanded disposal gloves, face masks, etc in the hospital. Incinerate clinical waste destroys the pathogen effectively, reduces the chance of transmission disease and yet potentially releasing secondary pollutants of gas emission and required landfill site for final disposal. Landfilling is not a sustainable and long-term solution because of the toxic leachate and greenhouse gas emission as well as the limited land in the future.