Sewage Sludge Analysis — EN 16179 / 86/278/EEC / Agricultural Use

What Is Sludge?

Sewage sludge analysis determines the pollutant content of sludge produced at wastewater treatment plants and its suitability for agricultural use. Heavy metals, organic pollutants, nutrients, dry matter, organic matter and pathogen indicators are measured.

Purpose of Sludge

The purpose is to determine whether the sludge can be used in agriculture or which disposal method is suitable. Agricultural use requires meeting limits both in the sludge and in the soil it will be applied to.

Which Products Is Sludge Applied To?

Domestic wastewater treatment sludge
Industrial treatment sludge
Stabilised and dried sludge
Composted sludge products
Water treatment plant sludge

In Which Sectors Is Sludge Used?

EnvironmentPublic SectorChemistryAgriculturePublic Sector

Standards Related to Sludge

TS EN 16179 (sludge, treated biowaste and soil — pretreatment of samples)
TS EN 16170 (determination of elements by ICP-OES)
TS EN 15934 (dry matter and water content)
TS EN 15935 (loss on ignition)
TS EN 16181 (determination of PAHs)
TS EN ISO 21528-2 / ISO 6579-1 (microbiological indicators)

Sludge Conditions

Dry matter: All results are reported on a dry-matter basis
Sampling: Taking a representative specimen from a sludge pile requires special care
Stabilisation: The stabilisation method applied (aerobic, anaerobic, lime) must be provided

Equipment for Sludge

ICP-OES / ICP-MS and microwave digestion
GC-MS
Oven and muffle furnace
Microbiology laboratory
Kjeldahl / Dumas nitrogen analyser

Sample Requirements for Sludge

Sampling is the largest component of total uncertainty in environmental analysis. The specimen container, preservation (acidification, cooling, storage in the dark), fill method and time to reach the laboratory are all defined in the standard; if any one is not met, the result loses its validity. Sampling must be carried out by authorised personnel per a written plan.
A representative specimen combined from different points of the pile
The dry matter ratio must be provided
The stabilisation method and the sludge's source must be stated

Duration of Sludge

Dry matter and metal analyses take several working days. Microbiological parameters require their own incubation times; organic pollutant screens take longer.

Sludge Procedure

1A representative specimen is taken from the sludge pile.
2Dry matter and organic matter are determined.
3The specimen is prepared per EN 16179.
4Digestion and ICP measurement are performed for metals.
5Extraction and GC-MS measurement are performed for organic pollutants.
6Microbiological indicators are analysed.

Sludge Acceptance Criteria

86/278/EEC defines heavy metal limit values for sewage sludge used in agriculture and permitted levels in soil; national legislation can add further parameters and pathogen requirements. Applicable values are confirmed from current legislation.

Evaluation of Results

Results are assessed on a dry-matter basis; a value given on a wet-specimen basis is not suitable for comparison. For agricultural use, the sludge being compliant is also not enough — the soil it will be applied to must have a metal load below the limits.

Sludge Report

Sludge source, stabilisation method and sampling information
Dry matter and organic matter ratio
Heavy metal results (on a dry-matter basis)
Organic pollutant and microbiological results
Regulatory limit values compared against

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

86/278/EEC Sewage Sludge Directive
2008/98/EC Waste Framework Directive
1999/31/EC Landfill Directive

Environmental Analysis — What Does This Testing Field Cover?

The section below describes the field that the Sludge test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Environmental analysis determines the presence and concentration of pollutants in water, soil, waste, air and flue gas samples. The output of this family is usually part of a permit, a declaration or an inspection file; the result has direct legal consequences.

In this family SAMPLING is half the result, and this is the feature that most sets the field apart. A sample taken at the wrong time, in the wrong container, under the wrong preservation or from the wrong point gives an invalid result no matter how well it is analysed in the laboratory. In waste water a grab sample and a composite sample give different information; in soil, surface and depth produce different results. Sampling therefore has its own standards and its own accreditation scope.

On the water side, physico-chemical parameters (pH, conductivity, turbidity, COD, BOD, suspended solids), ions, heavy metals, organic pollutants and microbiological parameters are measured. Drinking water and waste water carry different parameter sets and different limits; the same laboratory method leads to a different decision under the two regimes.

In soil and waste, heavy metals, hydrocarbons, PAH and PCB compounds and LEACHING BEHAVIOUR are determined. The leaching test carries a logic peculiar to this field: it is not the total amount of a pollutant in soil but the fraction that can pass into water that determines the environmental risk. Waste classification and the disposal decision rest largely on this test.

On the emissions side, dust, sulphur dioxide, nitrogen oxides, carbon monoxide, oxygen, moisture and total organic carbon are monitored in flue gas. Measurement is made on site under operating conditions and must represent the plant's actual operating regime; a measurement taken at low load does not show the emissions at full capacity.

Continuous measurement systems are a separate body of work. In large plants emissions are monitored continuously and the accuracy of these systems is verified periodically by comparison with independent measurements; the quality assurance framework governs this.

Noise and vibration measurements complete the environmental impact side of the field: environmental noise mapping, workplace noise exposure and vibration exposure measurements produce evidence for both environmental and occupational health legislation.

Method groups in this field

Sampling
Separate sampling standards for water, waste water, soil, waste, flue gas and ambient air; grab, composite and continuous sampling techniques.
Water physico-chemical
pH, conductivity, turbidity, colour, suspended solids, COD, BOD, TOC, alkalinity, nitrogen and phosphorus species.
Elemental analysis
Determination of heavy metals and trace elements in water, soil and waste by ICP-OES and ICP-MS.
Organic pollutants
Volatile organic compounds, PAH, PCB and organochlorine pesticides by GC-MS; hydrocarbon oil index.
Flue gas
Measurement of dust, SO2, NOx, CO, O2, moisture and total gaseous organic carbon; quality assurance of automated measuring systems.
Leaching and waste characterisation
Leaching tests and waste classification parameters; the basis for the disposal decision.

Commonly confused in this field

An analytical result cannot be used on its own without the sampling record; the time, point, conditions and chain of custody are part of the report.
Total content and leachable amount give different information; in waste classification, leaching behaviour is what counts.
Emission measurement must be made under representative operating conditions of the plant; a result taken at partial load is misleading.
Drinking water and waste water limits are defined in different legislation; the same parameter carries a different threshold under the two regimes.
A sample from a single point does not represent the whole area; assessment of a contaminated site requires a grid-based sampling plan.

Which decisions these results support

Compliance with environmental permits and discharge limits
Quality assurance of continuous emission measurement systems
Contaminated site assessment and the remediation decision
Waste classification and selection of the disposal method
Workplace exposure measurements and occupational health obligations

Related Tests

Frequently Asked Questions About Sludge

Our sludge came out compliant — can we use it in agriculture?

The sludge's compliance is only one of the conditions. The application soil's metal content, application dose, crop type and waiting periods are also defined in legislation, and all must be met.