標準號：BS EN 1899-1-1998
中文標準名稱：水質.數天后生化需氧的測定.加入烯丙基硫醇的稀釋和接種法
英文標準名稱：Water quality - Determination of biochemical oxygen demand after n days (BODn) - Dilution and seeding method with allylthiourea addition
標準類型：Z16
發布日期：1998/12/15 12:00:00
實施日期：1998/12/15 12:00:00
中國標準分類號：Z16
國際標準分類號：13.060.50
適用范圍：This European Standard specifies a determination of the biochemical oxygen demand of waters by dilution and seeding with suppression of nitrification. This standard is applicable to all waters having biochemical oxygen demands greater than or equal to the limit of determination 3 mg/l of oxygen and not exceeding 6 000 mg/l of oxygen. For biochemical oxygen demands greater than 6 000 mg of oxygen/l, the method is still applicable, but the errors caused by the necessary dilutions can influence the analytical quality of the test method and the results are to be interpreted with circumspection. In this standard the limit of detection, DL, is defined as DL = t0,95(f)·2·sB·1+1/n (1) where sB is the within series standard deviation,t0,95(f) is the student t-value, with f is the degrees of freedom for the determination of sB and n is the number of analysis for determination of the blank in an analytical series, sB is calculated from determinations of real samples with a BOD content near the estimated DL. In cases where the analytical method does not require any blank correction the term 1+1/n (2) is omitted. The results obtained are the product of a combination of biochemical and chemical reactions. They do not have the rigorous and unambiguous character of those resulting from, for example, a single, well-defined, chemical process. Nevertheless, they provide an indication from which the quality of waters can be estimated. The test can be influenced by the presence of various substances. Those which are toxic to microorganisms, for example bactericides, toxic metals or free chlorine, will inhibit biochemical oxidation. The presence of algae or nitrifying microorganisms can produce artificially high results. It is absolutely essential that tests conducted according to this standard are carried out by suitably qualified staff. Annex A describes alternative incubation periods. Annex B describes multitesting, which can be used to obtain enhanced precision or to demonstrate the presence of substances toxic to microorganisms.