Study On Haccp Assessment System Of The O₃-BAC Process Aquatic Biological Risk Assessment

Ozone biological activated carbon technology widely used in southern China,the process may be introduced as well as invertebrates and microorganisms in theprocess of internal proliferation as one of the main safety risks in the process. Thestudy evaluate the safety risks of biology in O₃-BAC process efluent with HACCPevaluation system, prevention and control of the outbreak of large-scale biologicalhazards, and thus protect the public safety of drinking water.The study preliminary evaluates of the penetration of biosafety risk level inO₃-BAC. which held that the O₃-BAC process, the greatest risk of hazardous eventsin source water, carbon filter and clean water tank. Source water due to theintroduction of invertebrates have been confirmed100%will carry the bacteria orpathogenic microorganisms, therefore, determine the possibility of level5, becausethe harm is the most direct source of process safety risk severity rating of Level5,the risk rating of25; calculated the carbon filter effluent microorganisms more than3500CFU/ml, may cause90%invertebrates and microorganism exceeded in thecarbon filter effluent, the hazard events possibile level reached grade5, severityassessment reached Level5, the risk level of25; according to the disinfectant dosagein clean-water reservoir and the the actual monitoring data, there will be almost100%living worm or dead invertebrates, which prove that the water in clean-waterreservoir disinfection is not complete despite disinfection and invertebrates residuesremain in the water, subsequently leaking to the pipe network, so it can bedetermined the possibility of hazardous events rating of Level5, the severity ratingof Level5, risk rating to grade25.Experimental verification, when translating the size of the three types ofbiological hazards posed into the proportion of invertebrates in the carrying amountof bacteria, and ultimately to evaluate the total bacterial penetration, as well as thetypical opportunistic pathogen Pseudomonas aeruginosa, integratedbiological levelof risk assessment can be evaluated by the highest level of risk for various types ofbiological evaluation.As defined the risk assessment, the critical control points can be determinedand develop the critical control limits through lab experiment. It shows that thecritical control points are sedimenanktation tank, sand filter, BAC filter, clean-waterreservoir.Which,shows that addition of ClO₂0.8².0mg/l before sedimenanktation tank will be effective in preventing the outbreak of the worm; at sand filter, sandparticle size should be less than1.35mm, the filtration rate is less than11m/L, andsand filters after dosing of O₃2⁴mg/L can effectively control the risk ofoutbreaks of the worm; addition a physical network to intercept in the activatedcarbon filter outlet （pore diameter≤200mesh （75μm）） or addition of ClO₂0.8².0mg/l/ammonia≥3mg/chlorine≥10mg/l, can effectively controlthe risk ofoutbreaks of vertebrates; in clean-water reservoir outlet to add a physical network tointercept （pore diameter≤200mesh （75μm））, or the dosing of ClO₂0.8².0mg/l to control the aspects of a possible outbreak of invertebrates security risk.