Study On Preparation Of Marine Oil Spill Repair Agent Using Shell Powder As Carrier

Bioremediation is widely used in marine oil spill accidents due to no secondary pollution to the environment.Addition of nutrient salts(biostimulation)and petroleum hydrocarbon degrading bacteria(bioaugmentation)can promote the degradation of marine oil spills.However,the natural marine environment is an open system.Nutrients and degrading bacteria can easily be diluted and lost,making it difficult to achieve the desired degradation effect.However,attaching nutrients and degrading bacteria to the carrier helps to improve the degradation efficiency.As a kind of natural biological calcium carbonate material,shell powder has large porosity and specific surface area and good adsorption ability.It can disperse the oil film into oil droplets and is not easy to be degraded.It is an ideal material for bioremediation.Therefore,the purpose of this paper is to develop a new type of oil spill repair agent with shell powder as a carrier,and to provide a new idea for the recycling of marine waste resources.The conclusions of the dissertation are as follows:The petroleum hydrocarbon-degrading bacteria were screened from the natural seawater and sediments taken from a nearshore beach in Jingmen Wharf in Tianjin,near the National Marine Museum and Yongding Island Park by stepwise domestication,and the optimum cultivation conditions for the degrading bacteria(N,O)was disscussed.The results of shaking flask experiments showed that the low nitrogen(C(NH4+-N)= 0.13 mg/L),median nitrogen(C(NH4+-N)= 10.7 mg/L)and the high nitrogen(C(NH4+-N)= 21.3 mg/L),the degradation rates of petroleum hydrocarbons after 7 days were 6.44%,5.88%and 2.85%,respectively.The effect of dissolved oxygen on degradation was explored by means of non-aeration and aeration.It was found that the degradation rate of aerated bacteria group(21.19%)was significantly higher than that of aerated bacteria group(7.84%)at the end of experiment(34 days)Oxygen promotes the degradation of petroleum hydrocarbons.Therefore,when the concentration of NH4+-N was 0.13 mg/L,the degradation rate of degrading bacteria was the highest in short time(7 days)under aeration.The shake flask experiment was used to investigate the interaction between the shell powder and the oil.The changes of artificial seawater(salinity 25),fresh water,shaking and standing were observed,respectively.It was found that when the seawater and oscillation were simultaneously applied,There will be polymer production,so salinity and disturbance energy is an important factor affecting the role of shell powder and oil.Then the mixed system was composed of 0.1%(m/v)oil and 0.05%,0.1%and 0.2%(m/v)of shell powder,respectively.The morphology of the oil droplet-particle aggregates(OPAs)was observed and the amount of OPAs was determined.The morphology of OPAs was found to be the most common shape that was multiple droplets and when the quality ratio of shell powder and oil was 1:1,the amount of OPAs produced was the largest,reaching 71.3%.The bacterial liquid was added into 6%inoculum in different concentrations of shell powder solution.The viable count method was used to calculate the number of bacteria adsorbed by the shell powder,and the amount of bacteria adsorbed by the shell powder was 1.8 × 1010CFU/g.In NH4+-N concentration of 10.7 mg/L and the proportion of shell powder and oil added and continued to inflate,the oil spill repair effect after additing shellfish powder was discussed.The results showed that the biodegradation rates of the bacteria group,bacteria nitrogen and phosphorus group,bacteria shell powder group and bacteria shell powder nitrogen and phosphorus group were 3.11%,13.47%,30.44%and 42.51%,respectively.The degradation rate of petroleum hydrocarbon in shell powder group was higher than that without shell powder group.Therefore,the addition of nitrogen and phosphorus nutrient-rich shell powder greatly promoted the degradation of oil spills.