What is a sustainable landfill design?

A landfill, a system of waste disposal, is hardly connected with enchanting terminology. Landfill expansion is not an ideal option for the community. We still have to live with it since our garbage is produced daily. The gatekeeper is how we manage the landfill in an environmental-friendly way.

SENT landfill is one of the landfills operating under sustainable design (https://www.epd.gov.hk/epd/english/environmentinhk/waste/prob_solutions/msw_sent.html)

First, the Bottom Liner System is applied to avoid underground water contamination. The wanted liner material is polyethylene (HDPE), which has high density, is strong, resistant to most chemicals, and impervious to water.

The lining system is multi-layered. In the SENT landfill of HKSAR, which collects construction waste only, the layers consist of a non-woven geotextile cushion layer, textured HDPE primary liner, composite bentonite matting, textured HDPE secondary liner, and geocomposite groundwater drainage layer. The system will also collect landfill gas and leachate from obstructing the transfer from landfills to the environment.

Second, it is the leachate collection system. Leachate is the contaminated liquid caused by rainfall or surface water blending with waste and its decomposition products. The pipe network at the sump gathers leachate, which will be pumped to the biological treatment plant for treatment. Without the leachate collection system, leachate will seep underground. Leachate gathering is a critical step to avoid waste polluting the ground.

The biological treatment plant will initially release the ammonia content in the leachate. Pollutants in the leachate will be further cleared through bacteria consumption. The legal discharge depends on the chemical oxygen demand (COD) and biological oxygen demand (BOD).

Why are COD and BOD important to the discharge standards? They are vital measurements for the amount of oxygen that is required to break down pollutants in water. A good BOD and COD levels mean not much organic waste and oxidisable organic material presenting in the water. If the levels are high, the reduction of dissolved oxygen levels will eventually lead to anaerobic situations, which is harmful to higher aquatic life forms.

By: ANewR Consulting Limited, a digital environmental consultant headquartered in Hong Kong since 2008. Our expertise has grown into the context of air and water qualities, noise, green building, waste management, and remediation. With extensive know-how in environmental planning and assessment, feasibility study and policy review, ecological design, monitoring, and audit (EM&A), ANewR has matured to be a leading management consultancy. Standing in the digital transformation reign, ANewR has participated in various environmental digital projects – interactive 3D visualisation, immersive automation virtual environment, Virtual reality, automation system, and monitoring platforms.
(Website: https://anewr.com, LinkedIn: ANewR Consulting Group, Twitter: ANewR – Everyday Newer,
YouTube: https://www.youtube.com/channel/UCnpvmxnR9hbNxytSfBdfV8Q/videos)