Landfill wastewater

Photo: Landfill wastewater

Leachate treatment processes are thus designed specifically according to concrete landfill types. In most cases, these treatment processes represent a combination of several processes guaranteeing purification of leachate water outgoing from a landfill. The process design respects the wastewater purification to a level meeting all requirements of local sewer regulations or, as applicable, all requirements for discharging it to water streams. 

An example of contamination indicators monitored in leachate water:

pH, temperature, DS (dissolved substances), SS (suspended solids), CODCr (chemical oxygen demand), N-NH4+, Ba, Mo, Cu, Cd, As, Co, Ni, Pb, Hg, V, Ag, Zn, SO42-, CN-, Cl- and AOX (absorbable organic halides)

Landfill leachate treatment processes

According to the above-shown indicators, treatment processes for leachate from landfills are designed as follows:

• Accumulated wastewater is intensively aerated, pH adjusted and, if necessary, its temperature is increased for the purposes of subsequent ammonia from water stripping,
• The process of ammonia reduction in leachate runs partially in the accumulation sump but  mostly in the aerated (stripping) tower, in strongly alkaline environment and, as the case may be, under elevated temperatures,
• Before the inlet to the sedimentation reactor, there is a tubular mixer, into which all service chemicals are dosed (i.e. for precipitation of metals, coagulation flocculation),
• In the sedimentation reactor, chemical sludge is separated from cleaned water,
• The cleaned water stream is then brought to the filter for additional purification, from which the water stream flows off to the outlet (final) reservoir. At the same time, the terminal reservoir is the checking place for water sampling before discharging to a sanitary sewerage system;
• From the sedimentation reactor, the chemical sludge is continuously transferred into an agitated sludge tank and consequently to a chamber filter press for the sludge volume minimisation,
• The landfill leachate treatment process is situated in a moderately heated service building.