EXPLORING THE EFFECT OF DIFFERENT DILUENTS AND DILUTION RATIOS ON MICROALGAE GROWTH IN LANDFILL LEACHATE

Meng Di; Azianabiha  A Halip Khalid; Nazlina Haiza  Mohd Yasin; Tao Ding Gong

Meng Di School of Civil Engineering, College of Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
Azianabiha A Halip Khalid School of Civil Engineering, College of Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia https://orcid.org/0000-0003-1598-9424
Nazlina Haiza Mohd Yasin Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. https://orcid.org/0000-0003-0888-8780
Tao Ding Gong China-Malaysia National Joint Laboratory, Biomedical Research Center, Northwest Minzu University, Lanzhou https://orcid.org/0000-0001-7884-4869

Keywords: Landfill leachate, Chlorella sorokiniana, diluent medium, biomass productivity, wastewater treatment

Abstract

The escalating discharge of landfill leachate presents significant environmental challenges, posing serious risks to ecosystems and public health. Leachate is characterised by its complex composition, high toxicity, and significant pollutant load, making its treatment and disposal a persistent issue for waste management systems worldwide. However, its nutrient-rich nature, including high concentrations of nitrogen, phosphorus, and trace elements, suggests it could be repurposed as a resource rather than merely treated as waste. This study explores the use of landfill leachate to culture Chlorella sorokiniana, focusing on its ability to support microalgae growth and enhance biomass productivity. Specifically, the study examines Chlorella sorokiniana growth in media derived from three different leachate treatment ponds (raw pond, Sequencing Batch Reactor Pond, and Dissolved Air Flotation Pond) and also investigates the growth of leachate in various diluents, including tap water, lake water, grey water, and rainwater. The best diluent is selected based on its characteristics and ability to support microalgae growth. It was subsequently used to dilute the leachate at concentrations of 25 %, 50 %, 75 %, and 100 % (v/v). Findings revealed that leachate from the raw pond provides the most suitable conditions for microalgae growth due to its balanced organic content, moderate suspended solids, low colour and suitable pH. Microalgae cultivated in this medium outperformed the other two ponds, achieving the highest specific growth rate (0.52 /day), cell division rate (0.75 divisions/day), and biomass productivity (14.17 mg/L/day). Analysis of diluents showed that tap water was the most favourable medium for microalgae cultivation, and when used to dilute leachate to 25 %, it provided optimal growth by minimising inhibitory effects. These findings underscore the critical role of leachate composition, diluent selection, and dilution in optimising microalgae-based treatment technologies.