Study On Early Warning Model And Emergency Treatment Of Black And Smelly River In Island City

The evaluation and research on the change of water body black and odour are all based on inland city river course,but the research on water body black and odour of island city is less than that of island city,which is the special environment of sea island city.The single factor index method is often used to judge the water quality,and this method is not enough to evaluate all the black and smelly phenomena.In this study,the black-smelly channel of Zhoushan City,the iconic island city,was taken as the research object,and the change of water black-odor was simulated.The main characteristic indexes of the black-smelly process were analyzed.The higher the content of COD,ammonia nitrogen and sulfate,the more significant the black-smelly-smelly.Within 7 days,the threshold value of black smelly was COD>50 mg/L,DO<2 mg/L,ammonia nitrogen>5 mg/L,sulfate>10 mg/L,>10 mg/L,temperature was in the range of 30℃—40℃,and the black smelly was obvious.The variation of microbial diversity before and after the black-smelling process in river water was studied,and the results showed that the key population of black-smelling microorganism Clostridium sensu stricto-1,and the number of key dominant microorganisms in the black-smelly water during the period of black-smelly outbreak was more than 20000/mL.Accounting for 64.09%of the total,the correlation mechanism of the main indexes of the black smelly process was established,and the early warning model of the black odor was constructed by synthesizing the indexes of the influencing factors of the water quality.The multiple linear regression was carried out between each water quality index and the blackness of the water quality.Ammonia nitrogen,sulfides,DO,ORP are negative correlation,COD,ammonia nitrogen,sulfides are positive correlation.The contribution of dissolved oxygen and sulfides to dependent variables was 95%according to the goodness of fit,and the odour model TO=1.6053-0.1367DO-0.00020RP-0.0048COD+0.05808NH3-N+1.18565S2-.The black and smelly index I=(0.672COL+0.328TO)*1.084(T-10)/10,and the model is used to predict the observed results in accordance with the actual river course,and the accuracy is 90%.It can be used as a prediction model for the black and smelly water quality of Zhoushan River,and the combination of environmental friendly hydrogen peroxide and bleach is used as a chemical inhibitor to carry out the small-scale experiment of emergency treatment of the black and smelly water body.When hydrogen peroxide was combined with bleach powder,the dosage of hydrogen peroxide and bleach powder were 5 mL/m3 and 10 g/m3,respectively,and the interval between them was 45 min.After the small-scale experiment of emergency treatment of black smelly and adding chemical agents,the black and smelly of water body was effectively restrained,and the water quality indexes returned to normal.The water quality monitoring and management of the 200 m section of the Lincheng River near the Qiandao Street in Zhoushan is carried out for a period of three months.The water quality prediction model is used to judge the black and odorous grade,and three times of water quality early warning need to be dealt with urgently.Chemical inhibitors need to be sprayed once to deal with the situation of black and smelly.After spraying chemical inhibitors,the effect is remarkable,and the water quality is effectively prevented from further deterioration,so that the water body is restored to a odorless state.