Preparation Of Dopamine Composite Membrane And Its Application In Aquaculture Wastewater Treatment

In recent years, with the rapid development of aquaculture, marine aquaculture has increaseddramatically in both size and number.If marine aquaculture wastewater discharge without effectivetreatment, it will leads to the pollution on the adjacent waters. At present, processing methods ofdisposing marine aquaculture wastewater include physical method, chemical method andbiological method.Those methods mainly remove the solids in the wastewater (SS), ammonianitrogen, chemical oxygen demand (COD), biological oxygen demand (BOD), in order to makethe Water Quality achieve the recycling or discharge requirements. According to thecharacteristics of marine aquaculture wastewater, these methods above have some shortcomings.Compared with the traditional water treatment of aquaculture wastewater, membrane technologyhas the advantages of convenient operation, high efficiency, it can make up for the deficiencies ofthe traditional process for the treatment of aquaculture wastewater. But the membrane pollutionproblems block the application of membrane technology. In order to reduce the membranepollution, study on preparation of meet the aquaculture wastewater treatment anti foulingultrafiltration membrane and its application in aquaculture wastewater treatment have broadapplication prospects.L-3,4-two hydroxyl phenylalanine (L-DOPA) is a special kind of crustaceansmussels in thesea of secretions, spontaneous polymerization under certain conditions, it has a strong attachmentto the material surface. The marineanimal extracts not only has a large number of hydrophilicgroups, also has thecharacteristic of anti biofouling in seawater, the dense cortical membranes canbe prepared, strong hydrophilicity and anti fouling of high performancecomposite membrane.In this paper, polysulfone ultrafiltration membrane is support membrane, coating thedopamine system to get dopamine composite polysulfone membrane.And also evaluating thecharacterization and performance of it. After the composite membrane preparing, we use it to separate aquaculture wastewater, the main conclusions are as follows:（1） Preparation of dopamine composite membranesThe polysulfone membrane with deionized water rinse well, after soaking,immerse,oscillation cleaning isopropanol. The cleaned polysulfone membranein membrane tank, dopaminesolution50mL is added into2g/L, adding a certain amount of oxidant function layer thickness,quickly closed the reaction pool in shaking culture box,37℃oscillation for12h, then fullyoscillation cleaning and ultrasonic cleaning, preparing the dopamine composite membrane.The sodium periodate as oxidant, addition of oxidant molecules to dopamine selfpolymerization, thus affecting the composite membrane layer thickness. This paper chose to jointhe sodium periodate were0g,0.005g,0.01g,0.02g, our gradient, with sea water as solvent is afour film, Lp values were1476.20、1015.65、811.30、169.03L·m-2·h-1·Mpa-1. The four film on theinterception rate of HA were78%,84%,86%,92%. Fluxes of the four membranes for HA were87.19、70.67、60.83、21.59L·m-2·h-1.（2） Dopamine composite membrane characterizationThe polysulfone membrane, the composite membrane prepared water as solvent and usingseawater as adding sodium periodate oxidant solvent(0g,0.005g,0.01g,0.02g,four gradient)measurement of four kinds ofcomposite membrane prepared respectively by infrared scanning,scanning electron microscopy, film thickness and contact angle. The results showed,infraredscanning spectrum analysis of the S=O stretching vibration peak at1250cm-1, at1600cm-1and1510cm-1overlap peaks of C=C resonancepeaks of aromatic rings and bending vibration, theseare the characteristic peaks of polysulfone membrane. In the3500~3600cm-1stretching vibrationpeak appeared in N-H/O-H,1519cm-1appeared N-H shear vibration peaks of amino group,1394cm-1appeared vibration peaks of C-O-H, are thecharacteristic peak of dopamine, dopamineis that surface polymerization onthe polysulfone membrane. Scanning electron microscopyshowed that, withoutthe oxidant molecule polymerization will on the surface of polysulfonemembrane, but less in quantity, with the added oxidant capacity increases,more and moredopamine molecule polymerization on the surface of the membrane, as oxidizing agent to join0.02g, the surface pore was completelydopamine molecules covering, film formed on the surfaceis a dopaminecomposite layer a dense, homogeneous. Polysulfone membrane, thecompositemembrane prepared by water as solvent and using seawater asmembrane solvent adding sodium periodate oxidation agent0.005g,0.01g,0.02g,0.05g of the prepared thick respectively is:209.89μ m,210.67μ m,213.56μ m,229.44μ m,237.22μ m,239.11μ m contact angle, respectively is:79°,63°,57°,52°,49°,42°, with oxidant increased more dopaminemolecule polymerized onthe surface of the membrane, the hydrophilicity of the membrane with oxidant demand increase.(3) Treatment of aquaculture wastewater by dopamine composite membraneExperiments with polysulfone membrane and dopamine composite membranesolvent addingsodium periodate0g,0.005g,0.01g using seawater as theshrimp aquaculture wastewater treatmentexperiment, processing pressure0.15MPa. Four kinds of aquaculture wastewater membranetreatment, total suspended solids are removed, the removal rate of COD were:72.2%,83.3%,83.8%,90.8%; aquaculture wastewater into the dopamine0.01g composite membraneprocess sodium periodate prepared after the COD, pH, ammonia nitrogen, and dissolved oxygenconcentrations were2.19mg/L,3.55mg/L,8.13and5.62mg/L. Except for ammonia and nitrogen,are up to second class of sea water quality standard, a small amount of residual ammonia canbetreated by ozone oxidation standard of sewage reuse.