Study On The Cause,inactivation Method And Removal Technology Of Chironomus Larva And Tubificid In Reclaimed Water

The pollution control of aquatic animals in water treatment process has always been a problem that needs to be paid attention to,among which the problem of Chironomus Larva pollution is a key problem at home and abroad in 2000,which has been well contained and solved through continuous research.However,in 2018,the thermal power plant in Qinghai reappeared the problem of Chironomus Larva pollution.Through preliminary tests,it was found that the early methods could still achieve good treatment effect,but the dosage of chemicals increased significantly.The dosage to achieve good killing effect has far exceeded the range of conventional requirements in the water treatment process,which shows that the current Chironomus Larva resistance is stronger.In this paper,the chemical oxidants such as sodium NaClO,KMnO₄,H₂O₂and ClO₂ were used to inactivate the fourth Chironomus Larva and the red thread worm in the water.The effects of dosage,pH value,contact time,insect density and coexisting organic matter on the inactivation were discussed respectively.Among them,the research on insect density is of great significance to improve the economic feasibility of high dosage.?1?The results showed that the killing rate of conventional chemical oxidants on the Chironomus Larva was low,the killing effect of chlorine dioxide was better under the condition of long-term contact and high dose.Under the condition of pH<4,NaClO can obviously improve the killing effect on red insects,but the dosage still needs to reach 200mg/L,which is difficult to be applied in practice.?2?Under the experimental conditions,when the dosage of NaClO,KMnO₄ and H₂O₂ is 20-200mg/L,the killing effect of the three reagents is poor,and the highest inactivation rate of the three reagents is only 11.1%when they are exposed for 60min.The mortality of larva increased with the extension of contact time,but the highest inactivation rate could only reach 50%when it was extended to 6h,even after 24 hours of contact,it could not reach 100%inactivation rate.?3?Chlorine dioxide has a good killing effect on the Chironomus Larva,but it needs a higher dosage and a longer contact time.For example,when the dosage reaches 52mg/L after 60 minutes of contact,it can reach 100%inactivation;when the dosage is 38-46mg/L,it needs 3-4h of contact to make the Chironomid larvae completely dead.The pH value had little effect on the efficacy of chlorine dioxide in killing Chironomus Larva.Some chlorine dioxide will be consumed by organics in the water,which will reduce the inactivation effect and prolong the inactivation lethal time.?4?The increase of density has little effect on the inactivation of Chironomus Larva,and it can still keep 80%inactivation rate under the ultra-high body density,which greatly improves the economic feasibility of using chlorine dioxide to inactivate Chironomus Larva under the condition of high dosage,and provides a solution for the problem of strong resistance to aquatic biological pollution in the future.?5?H₂O₂ has almost no inactivation effect on the tubificid,while NaClO,ClO₂and KMnO₄ have some killing effect.Under neutral condition,the order of inactivation performance of each agent is:NaClO>ClO₂>KMnO₄>H₂O₂.Prolonging the contact time is helpful to improve the inactivation effect of chemical oxidants.NaClO and chlorine dioxide can effectively kill the tubificid,and the inactivation rate of 2mg/L NaClO can reach 100%under the condition of contact for 60min,while chlorine dioxide needs 8mg/L.The effect of KMnO4 is general.Under the dosage of 10mg/L,the inactivation rate can reach 72%in one hour.To reach 100%inactivation rate,the contact time should be extended to 2h.The order of pH value adaptation of each agent:ClO₂>NaClO>KMnO₄.