Wastewater testing services

We routinely test wastewater samples for process control purposes in wastewater treatment plants and analyse trade waste samples from industrial activities to ensure compliance with discharge permits.

Where environmental licences (e.g. linked to wineries and dairies) require periodic sampling and testing of samples to ensure compliance we can also help.

Our testing includes BOD, COD, Cyanide, Phenol (total), Sulphides, Alkalinity (sludges), Chlorine residuals, UV absorbance and Oil and Grease. Various measurements of solids are available including Total Dissolved (TDS, derived from conductivity but also by evaporation), suspended (SS), volatile suspended (VSS) and total (TS) and volatile solids (VS).

Biochemical Oxygen Demand (BOD)

BOD is usually defined at the amount of oxygen required by bacteria while stabilising the decomposable organic matter under aerobic conditions and so the BOD test is widely used to determine the pollutional strength of domestic and industrial wastes in terms of the oxygen that they will consume if those wastes are discharged into natural watercourses.

Changes in BOD as wastewater passes through a wastewater treatment plant can be used as a guide to that plant's efficiency and to pinpoint potential trouble spots.

Chemical Oxygen Demand (COD)

COD is also used a means of measuring the organic strength of wastewaters.

The test relies on the oxidation of organic matter by a strong oxidising agent under acidic conditions. COD measurements will always be greater than BOD measurements and the difference is linked to the biodegradability of the organic matter present in the sample.

For example, the COD of a wastewater from a wood pulping waste will be significantly higher than the BOD because there is a significant amount of non-biodegradable material present.


There are various types of solids that can be measured and we can guide you on the best method to achieve your goals.

The usual definition of solids refers to material that remains after drying. This material consists of two components; one being dissolved material made up mainly of inorganic salts but also potentially dissolved gases and some organic material and the other, undissolved material is referred to as suspended solids (SS), suspended matter or sometimes non-filterable residue. The filterable residue can also be determined and is known as Total Dissolved Solids by evaporation.

Other useful solids tests are to carry out Total and Volatile Solids analysis on sludge samples to estimate the amount of organic matter present. By first drying a sludge sample and then combusting the sample at 550oC, an estimate of the inorganic (ash) and the organic (volatile) fractions of the total solids can be determined.

We analyse wastewater samples, particularly those sourced from industrial sites for cyanide (from plating baths), phenols and Sulphides.

Oil and Grease

The oil and grease content of wastes is an important consideration in the handling and treatment of these materials for ultimate disposal. Often, the amount of grease that can be disposed of into a sewerage system will be carefully controlled through the use of a trade waste permit.

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