| In recent years,algal blooms in the Haihe River have occurred frequently.The treatment of algae blooms in Haihe River should proceed from the final disposal of cyanobacteria to build a strong,efficient and rapid application.The emergency management technology system provides reference and reference for the emergency plan for the outbreak of algae blooms in the mainstream of the Haihe River.(1)In view of the current situation of outbreaks of river blue-green algae,this paper selects catch-swirling-dehydration technology,we have designed and developed mechanical salvage system equipment with a wide collection area,strong processing capacity and stable effects.The emergency fishing demonstration operation test was conducted at two cyanobacterial outbreaks in Haihe,Tianjin.(2)Based on the Stokes law,a hydrocyclone separation device with high separation efficiency and low power consumption was developed.On the basis of comprehensive analysis of cutting particle size and pressure drop,Fluent series software was used to establish a fluid calculation model to simulate the flow field and explain the motion of cyanobacteria in a swirling liquid separator.(3)Three kinds of filter aids,polyaluminum chloride(PAC),montmorillonite and diatomite,were added to the algae to study the effect of filter aids on the filterability of algae.The results show that the three filter aids have a certain improvement effect on the filtration rate,specific resistance,compression index and dehydration efficiency of algae,and the filtration rate of diatomite is relatively faster than that of the other two filter aids.The dehydration performance is relatively good.When the dosage is 10.0g/L,the filtration rate increases from 0.108L/h to 0.504L/h,the compression index decreases from 0.710 to 0.594,and the specific resistance of algae fluid is 7.62×1010s2/g decreased to 2.35×108 s2/g,and the filter cake moisture content decreased from 86.5%to 66.4%.(4)The diatomite as a filter aid,the best dosage is 10.0 g/L,and the cost is relatively high.Therefore,the diatomite is calcined to reduce the amount of diatomaceous earth.The calcined diatomite was used as a filter aid.The filtration rate of calcined diatomaceous earth was significantly increased,and the filter cake compression index was 0.It was an incompressible material with a water content of 57.66%.The dehydration efficiency was comparable to that of raw silicon.The algae soil increased by 8.74%and the dosage was relatively reduced.The experimental results show that calcined diatomite can be added to the dewatering process of algae.The optimum temperature for calcining is 700 ?.When the algae concentration is 1 ×109 cells/mL,the optimal dosage is 2 g/L.The use of calcined diatomaceous earth as a filter aid to dehydrate cyanobacteria can increase the dehydration efficiency of cyanobacteria by 28.83%.It is economical and feasible,and it is harmless to follow-up resource treatment,and it is also an emergency for algal blooms.Disposal and resource utilization are of great significance.(5)The dehydrated cyanobacteria are resource-utilized using aerobic composting.In the 1#container after composting,organic matter decreased by 165.31g/kg,total nitrogen increased by 5.99 g/kg,ammonium nitrogen decreased by 2g/kg,C/N decreased to 14.73,and seed germination index GI was up to 87.41%.In the process of composting,the temperature of the stack in the container changes more rapidly with the set temperature of the tank,indicating that the 1#container has the best composting effect in the cyanobacteria aerobic composting process,and the bottom area of the 1#container volume is larger.The low compost height makes the contact area between the surface of the heap body and the air increase,and the height reduction is conducive to the diffusion of oxygen and heat transfer. |
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