The Rotation System in Landfill Sites.

Landfill is the easiest way of disposing waste. But the major question is: Is it safe? If not managed properly, landfill can create various problems to human health and its surrounding environment. One of the crucial problems is accumulation of leachate which can create an increased risk of seepage from the site, causing a negative effect on the environment. The alternatives of discharging the leacheate are:
• Direct discharge to sewer,
• Treatment followed by discharge to sewer,
• Treatment followed by discharge to watercourse,
• Shipment by tanker to a third party,
• Pre-treatment of leachate in a “facultative” lagoon system, followed by drip irrigation onto short rotation coppice (SRC), maximising SRC growth to produce a biomass products (environmentally-accepted option).

The process of the fifth option uses two pre-treatment steps, undertaken in primary and secondary lagoons. Liquid levels in the primary lagoon are maintained consistently throughout the year, the excess being transferred to the secondary lagoon where it receives further treatment. Liquid levels in the secondary lagoon fluctuate during the year, being reduced during the spring and summer as a consequence of irrigation, and recovering over winter. The secondary lagoon is designed to provide winter storage of treated leachate for use as an irrigation resource for the following growing season.

The facultative leachate treatment process seeks to encourage a self-regulating environment that supports a complex community of aerobic, anaerobic and facultative bacteria (bacteria that can behave as either aerobic or anaerobic) resulting in an increased opportunity to degrade contaminants. The process utilizes three zones:
• An anaerobic (without oxygen) digestion zone at the lagoon base.
• A facultative intermediate zone which prevents the exposure of anaerobic bacteria to the aerobic environment.
• An upper aerobic with oxygen zone.


Compared to the aggresively mixed aerobic treatment processes, this process only requires gentle mixing, which also allows sludge self-digestion by encouraging all solids to settle within the anaerobic zone. With a lesser requirement to mix/provide supplementary dissolved oxygen this process benefits from generating negligible quantities of waste and, at the same time, requires significantly less power and process chemical requirements.

Utilizing the treated leachate as a water and nutrient resource, directly placed via ground water drip irrigation makes use of the plants’ high nutrient and water demands and aims to optimise the crop’s growth potential. However, approval of such schemes is required, as the process is considered to be biological treatment of waste.

Source: Molland, D. (2009) The Rotation System. CIWM. November issue