Water quality quick measuring method for indirectly measuring BOD5 (five-day biochemical oxygen demand) in water

Abstract

The invention relates to a water quality quick measuring method for indirectly measuring BOD5 (five-day biochemical oxygen demand) in water. The water quality quick measuring method comprises the following steps of diluting a BOD5 quality control sample or a standard sample into concentration which is the same with the concentration of a blind sample, respectively selecting 2ml of the BOD5 qualitycontrol sample or the standard sample and 2ml of the blind sample, adding into a CODcr (chemical oxygen demand) testing reagent, uniformly mixing, powering on a CODcr tester, and respectively respectively measuring the BOD5 CODcr content in the quality control sample or the standard sample and the BOD5 CODcr in the blind sample; calculating the BOD5. The water quality quick measuring method has the advantages that the limitation by water quality detection conditions is avoided, and the accurate and reliable detection result can be obtained within 2 to 3h; the influence to the measuring resultby various factors in the measuring process of the BOD5 blind sample is eliminated.

Description

technical field [0001] The invention belongs to the technical field of water pollution prevention and control, in particular to water quality five-day biochemical oxygen demand (BOD) 5 Blind samples and emergency monitoring methods for water pollution. Background technique [0002] Biochemical oxygen demand (BOD) refers to the amount of dissolved oxygen consumed by microorganisms in the biochemical process of decomposing certain substances that may be oxidized in water, especially organic matter, under certain conditions, expressed in mg / L . Water quality five-day biochemical oxygen demand (BOD 5 ) is the amount of dissolved oxygen consumed by microorganisms decomposing substances that may be oxidized in water at the most suitable temperature (generally 20°C is used as the standard temperature for measurement). Under the measurement conditions of BOD (sufficient oxygen, no agitation) at 20°C, the oxidative decomposition process of the first stage (99% of the process) can ...

AI Technical Summary

Problems solved by technology

[0003] The traditional five-day biochemical oxygen demand determination methods include the dilution and inoculation method (HJ505-2009) and the WTWBOD automatic measuring instrument differential pressure method (YWEC / ZZ·JF15-2015). The disadvantage of the dilution and inoculation method for assessing blind samples is that : When mixing salt solution, up to 7 kinds of salts need to be weighed and prepared. The temperature of the dilution water should also be controlled at room temperature of 20±1°C and aerated for 1 hour. The dissolved oxygen in the dilution water should be above 8mg / L, and The dissolved oxygen in the dilution water cannot be supersaturated, and the inoculum needs to be added to the dilution water. The inoculum can be prepared with humus soil or water with high microbial content, and can also be purchased

Traditional BOD 5 The blind sample assessment process is cumbersome and the accuracy rate is low

The differential pressure method of WTWBOD automatic measuring instrument also needs to add the inoculum to the blind sample during the measurement, and use the differential pressure generated by the microorganisms to consume oxygen in the water to calculate the BOD 5 The content of this method is much higher than that of the dilution and inoculation method, but the relative deviation of the comparison results of most samples exceeds the specification requirements, that is to say, the two methods are used to assess BOD 5 The blind sample is too small for the former and the latter is too large, it is difficult to put the BOD 5 The determination is within the allowable error range, and both methods have to be cultivated in a constant temperature incubator at 20±1°C for five days to produce results. In addition, when the temperature difference between day and night in the incubator used in HJ50 5-2009 is large, it is difficult to maintain the temperature at 20±1°C. °C range, resulting in BOD 5 The measured value is not accurate enough

In actual testing, since the monitoring results have to be reported within the stipulated time, the testing takes 5 days to measure, and there is no opportunity for reworked testing, which greatly reduces the accuracy of the testing results