Research On Simple And Fast Microfluidic Assessors For Effective Disinfection And For The Quality Of Ships Ballast Water

In compliance with the Regulation D-2 standard of the International Convention for the Control and Management of Ships' Ballast Water and Sediment,the ballast water is treated by chemical,physical,mechanical or electrical methods.Existing treatment methods face many technical challenges.On one hand,the effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples,which involves time-consuming,laborious,and complex operations.On the other hand,the ballast water will be sampled and analyzed if the crew intends to discharge it into the sea.Historically,the analysis of ballast water quality has relied heavily on land-based laboratory microscopy and other labor intensive methods.If the result of laboratory analyses does not detect any dangerous microorganisms,all the expenses would be paid by the inspector.There is a clear need for a cheaper and faster analytical modality.Ship owners and port authorities need a more efficient system of inspection.New technologies could help to find better way for that all.The advantage of microfluidic sophisticated technology is that it can provide a solution of this problem.A new method to assess the efficiency of disinfection and ships ballast water quality is proposed in this dissertation.Firstly this paper introduces a microfluidic device for evaluating the efficiency and the parameters for ballast water treatment systems,particularly in chemical disinfection.The performance of this platform device was evaluated by detecting the disinfection of Dunaliella salina(D.salina)algae in natural sea water treated by sodium hypochlorite(NaCIO)solution.The combination of electroosmotic and electrophoretic method controlled sample flow as a microvalve in the microchannel.Laser-induced chlorophyll fluorescence(LICF)method was used to determine the viability of algae cells in the system,which can be automatically operated with the dimension of the detector as small as submillimeter size.Disinfection was shown in terms of amount of chlorophyll fluorescence intensity signals which were fast-response on the display screen.The 40 ?l volume of sample solution was used for each treatment condition test.There were included two main sets for tests.The first set compared the microalgae activity results under different reagent concentrations.The second set checked the viability of microalgae under different treatment times in a certain chemical reagent concentration.The results show that the viability of microalgae cells under different treatment conditions can be determined accurately.Secondly,this dissertation examined the organism detection options applicable to the indicator microbes identified in the D-2 standard.To evaluate the bacteriological quality of ship's ballast water and the risk of invasion of non-indigenous species both onboard ship and in Port,the jet-design channels microfluidic resistive pulse sensor(MRPS)was applied.Channel design led more efficient in flowing bacteria in the main channel and avoided aggregation.Escherichia coli(E.coli)and Enterococci were addressed in this article as bacterial indicators to determine of their quantities.The system provided the individual particle-by-particle readout in rather large 20?m ×10?m×8?m(length × width × height)horizontal rectangular microchannel duct.The average volume flow rate was 4.5 ?l/min.The real-time results for 30 ?l sample volume were returned during 15 min as a complete detection.This was because of the effect of using a sheath well instead external pump.The detected bacterium size was illustrated by the transient pulse signal height due to increase in resistance in electrolyte solution.The chip's structural design was increased to a hydrodynamic range and signal-to-noise ratio reached about 5 for detecting bacteria.Targeted bacteria needed neither labelling nor extracting DNA.The system was low maintenance,good accuracy and reliable.Also there are two more descriptions for IMO standard sizes that could be further measured by the viable unit.Also the analysis is to assess viability in microorganisms less than 10 ?m which are not covered in D-2 standard shall be addressed.Because of there may be other organisms and debris below 10 micron in minimum dimension that may be relevant,including invasive species that are present in much higher concentrations.The efficacy of ballast water management system to treat such organism should also be checked to evaluate how ballast water treatment will reduce the risk to spread these species.Finally,therefore,this article was aimed at simultaneous multisized detection and analyzing different taxa in sea water to present the ballast water quality.The device was framed as a ballast water compliance tool by means of a changeable microfluidic chip detector.The system was designed through the integration of microfluidic chip,the impedance pulse sensing and LED light induced chlorophyll fluorescence(LED-LICF)method.This system can measure the number,size,shape and volume of targeted microorganisms and it can also determine the chlorophyll fluorescence intensity which is an important factor in analysing the viable of phytoplankton.The targeted samples are Chlorella volutis,Dunaliella salina,Platymonas subcordiformis,Chrysophytes,Escherichia coli and Enterococci.A complete detection for each test can be accomplished in a few minutes with using micron volume of the sample solution.The valid data output results are simultaneously displayed in terms of both impedance pulse amplitudes representing the sizes of microalgae and fluorescent intensity signals representing the amount of chlorophyll in microalgae.The dimension of detection zone provided to choose limitation size of detection samples.The right choice will cause high sensitivity and avoid clogging.Three optimal dimensions for detecting zones were proposed here:150 ?m(L)× 80 ?m(B)x 80 ?m(H)for detecting between 20?50?m size of microalgae;80 ?m(L)× 40?m(B)× 40 ?m(H)for between 3?20 ?m size of microalgae;20 ?m(L)×10 ?m(B)× 8 ?m(H)for bacteria to until 2 ?m size;according to the results from several experiments.Regarding to it can successfully detect the label-free microorganisms,the system can be applicable to in-situ detections with other modifications.