Method for rapid assessment of the ecotoxicity
of sewage sludge on earthworms
Sewage sludge is the by-product collected during the various stages of wastewater treatment.
The quantity of sludge is measured by its dryness, i.e. by the proportion of dry matter it contains.
More than one million tons of dry matter are produced each year by wastewater treatment plants in France.
Source : IDEA du Coeur du Hainaut
This sludge can be recovered or disposed of.
The most commonly used recycling methods are agricultural spreading or composting. Between 2009 and 2011, 70-75% of the sludge from wastewater treatment plants was applied largely to agricultural land.
While sewage sludge is rich in nutrients and organic matter useful for amending agricultural soils, it can also contain more harmful components, depending on their concentration: TMEs (trace metals), organic micropollutants, pathogenic micro-organisms or medicinal substances.
Legally, the spreading of sewage sludge is governed by - in France - the modified Order of January 8, 1998 setting the technical requirements applicable to the spreading of sludge on agricultural land taken in application of the decree n° 97-1133 of December 8, 1997 relating to the spreading of sludge from wastewater treatment.Consult the Order
In order to preserve a good quality of soils, the French regulation foresees soon the the implementation of new measures. . These are additional controls on sewage sludge, prior to its recovery by composting or agricultural spreading in particular.
Among the possible tests is the evaluation of the ecotoxicity of sludge on earthworm reproduction. However, these tests require long lead times, in the order of a month, while water managers have storage capacity limited to a few days
In addition, some communities have embarked on a policy of increasing sludge recovery, making for a delicate context.
Our solution: GreenSludge
ViewPoint has developed a fast assessment method for earthworms.
From its automated behavioral analysis, GreenSludge provides the ecotoxicity score of the sample within 24 to 48 hours after receipt at the laboratory.