China Education Equipment Purchasing Network News: Recently, Belgium Applitek's online toxicity analyzer Ra-TOX was successfully installed in the Guangzhou West District Water Quality Purification Plant for early warning of the toxicity of water intake water quality of water plants. The Guangzhou West District Water Quality Purification Plant is located in the Xiji Industrial Zone of the Guangzhou Economic and Technological Development Zone, covering an area of ​​78,600 square meters. After the expansion, the total treatment scale is 75,000 tons / day. In the first phase, the traditional activated sludge process is used, with a treatment scale of 30,000 tons / day, and in the second phase, the CASS process is used, with a treatment scale of 45,000 tons / day. The online toxicity analyzer was installed in the second phase.
The water purification plant mainly treats chemical wastewater, among which heavy metal wastewater is the main one. Toxic heavy metal wastewater can easily reduce sludge activity and affect the sewage treatment effect. Once the sludge is poisoned, it must be replaced or re- domesticated, which will have a great impact on the normal operation of the sewage treatment plant, and even worse, it may lead to the paralysis of the sewage treatment plant. During the installation of the toxicity analyzer in our company, sludge poisoning occurred in the plant. At that time, the toxic wastewater caused the sludge in 5 of the 6 CASS process tanks to be poisoned, resulting in unstable effluent quality, but fortunately, the sludge in one tank was not affected. Afterwards, the sludge in the pond was mainly distributed to the other 5 poisoned ponds for re-acclimation and cultivation. It took a month to barely restore the activity of the sludge and stabilize the effluent quality. Therefore, the installation of an online toxicity analyzer is highly practical and necessary for early warning of incoming water toxicity.
After the instrument has been running for a period of time, a simulated toxicity test is performed on the online toxicity analyzer. In view of the fact that toxic wastewater is mainly heavy metal wastewater, copper chloride is used to prepare toxic wastewater. Prepare copper chloride solution with concentration of 1g / L, 0.25g / L and 0.25g / L respectively for toxicity experiment. The test found that the sludge respiration rate began to decrease after 5 minutes at these three concentrations, and the inhibition rate began to rise, indicating that the toxicity analyzer can quickly respond to toxicity even under low toxicity conditions; The response of low concentration toxicity is more rapid, the change range is larger, and the downward trend of respiration rate is more obvious. It can be seen from this that the toxicity analyzer has fast response time, low detection limit, stable operation, and can effectively achieve the purpose of early warning of toxicity.
Measuring principle and characteristics of online toxicity analyzer
working principle
The aeration tank is continuously and automatically filled with activated sludge, while adding wastewater to achieve maximum respiration rate. The analyzer continuously sends the mixed sample of sludge and waste water in the aeration tank to the breathing module Ra-3000. In the breathing module, a unique single dissolved oxygen sensor is used to measure the dissolved oxygen concentration of the sample in the breathing module. Each measurement is made in 2 opposite flow directions. Within a fixed time (30 seconds), the flow direction through the breathing module will be reversed once. The difference in dissolved oxygen concentration between these two times is the respiration rate (mgO2 / lh). The aerobic rate and respiration rate of activated sludge in the aeration tank are related to their vitality, and therefore also reflect the magnitude of the toxic effect. If the respiration rate in process conditions is only related to the toxic mixture in the sewage, then the reduction in respiration rate can indicate the effects of toxic substances. The toxicity analyzer can simultaneously measure and display: O2in, O2out, respiration rate Ra, short-term respiration rate average Rashort, long-term respiration rate average Ralong and toxicity inhibition rate%. Toxicity inhibition rate% = (Ra short-Ra long) / Ra long * 100%.
System composition:
Ra-3000 basic respiration measurement module sampling system Modusize
Aeration tank (3 liters)
pH controller (optional)
Nutrient addition system
characteristic
(1) Simulate the aeration and oxygen consumption of activated sludge in the biochemical tank. The real-time sludge of the sewage treatment plant is directly used for measurement, and continuous input is kept to keep it fresh, with the same pH value, temperature, water sample and sludge, and the toxic breathing rate is directly measured.
(2) A unique single dissolved oxygen sensor is used in the breathing module to measure the dissolved oxygen concentration of the sample in the breathing module. The double dissolved oxygen probe is not used to avoid the measurement error caused by the performance difference between the probes.
(3) No reagents are needed, and maintenance is small.
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