BS EN ISO 14853:2017 pdf download

BS EN ISO 14853:2017 pdf download.Plastics — Determination of the ultimate anaerobic biodegradation of plastic materials in an aqueous system — Method by measurement of biogas production
1 Scope
This International Standard specifies a method for the determination of the ultimate anaerobic biodegradability of plastics by anaerobic microorganisms. The conditions described in this International Standard do not necessarily correspond to the optimum conditions for the maximum degree of biodegradation to occur. The test calls for exposure of the test material to sludge for a period of up to 90 d, which is longer than the normal sludge retention time (25 to 30 d) in anaerobic digesters,although digesters at industrial sites can have much longer retention times.
The method applies to the following materials:
— natural and/or synthetic polymers, copolymers or mixtures thereof;
— plastic materials which contain additives such as plasticizers, colorants or other compounds;
— water-soluble polymers;
— materialswhich,underthetestconditions,donotinhibitthemicroorganismspresentintheinoculum.
Inhibitory effects can be determined using an inhibition control or by another appropriate method (see e.g. ISO 13641). If the test material is inhibitory to the inoculum, a lower test concentration,another inoculum or a pre-exposed inoculum can be used.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 ultimate anaerobic biodegradation
breakdown of an organic compound by microorganisms in the absence of oxygen to carbon dioxide,methane, water and mineral salts of any other elements present (mineralization) plus new biomass
3.2 primary anaerobic biodegradation
structural change (transformation) of a chemical compound by microorganisms, resulting in the loss of a specific property
4 Principle
The biodegradability of a plastic material is determined using anaerobic conditions in an aqueous system. Test material with a concentration of 20 mg/l to 200 mg/l organic carbon (OC) is incubated at (35 ± 2) °C in sealed vessels together with digested sludge for a period normally not exceeding 90 d. Before use, the digested sludge is washed so that it contains very low amounts of inorganic carbon (IC) and diluted to 1 g/l to 3 g/l total solids concentration. The increase in headspace pressure or the volumetric increase (depending on the method used for measuring biogas evolution) in the test vessels resulting from the production of carbon dioxide (CO 2 ) and methane (CH 4 ) is measured. A considerable amount of CO 2 will be dissolved in water or transformed to bicarbonate or carbonate under the conditions of the test. This inorganic carbon (IC) is measured at the end of the test. The amount of microbiologically produced biogas carbon is calculated from the net biogas production and the net IC formation in excess of blank values. The percentage biodegradation is calculated from the total amount of carbon transformed to biogas and IC and the measured or calculated amount of carbon added as test material. The course of biodegradation can be followed by making intermediate measurements of biogas production. As additional information, the primary biodegradability can be determined by specific analyses at the beginning and end of the test. This test method is designed to determine the biodegradability of plastic materials under anaerobic conditions. Optionally, the assessment of the recovery rate may also be of interest (see Annex G).