Anions in sewage effluent - Determination of Anions in Natural and Treated Waters - page 576

Table 9.2 Nitrate analysis of effluents of sewage treatment plants a

Sample no. Potentiometric NO 3 − N, mg L −1

Spectrophotometric b NO 3 − N, mg L −1

1 28 28

2 43 44

3 52 41

4 43 37

5 34 39

a The data represent a single analysis
b As measured independently
Source: Reproduced with permission from the Water Research Centre, UK [11]

purposes. Only chloride and, to a lesser extent, nitrite and bicarbonate interfere in these
measurements of nitrate.
Table 9.2 gives a survey of results obtained by both methods on sewage effluents with
a high nitrate content.

9.5.3 Miscellaneous

See section 14.12.6.1.

9.6 Nitrite

9.6.1 Miscellaneous

See section 14.12.6.1.

9.7 Nitrite and nitrate

9.7.1 Spectrophotometric method
Workers at the Water Research Centre UK [11] have described detailed procedures based
on the use of the Technicon Autoanalyser AA11 for the determination of nitrate and
nitrite in sewage and sewage effluents. Measurements of nitrate in sewage at the 10-
50mg L −1 level were made with a within batch standard deviation of 0.1mg L −1 nitrate.
Nitrate recoveries at the 12mg L −1 level were in the range 100-100.7%. Standard
deviations of nitrite determinations were in the range 0.003 (at 0.2mg L −1 nitrite) to 0.010
(at 1mg L −1 nitrite). Nitrite recoveries in the 0.4mg L −1 region were between 98 and
102%. Nitrate recoveries in the 12mg L −1 region were between 100 and 100.7%.