Disinfection efficiency of fine bubbles generated by hydrodynamic cavitation in the water phase (ISO TC281/WG3 New Proposal)

Transcription

1 Disinfection efficiency of fine bubbles generated by hydrodynamic cavitation in the water phase (ISO TC281/WG3 New Proposal) Nicholas Young Cheol PARK New Water Tec Co. Ltd., Rep. of KOREA

2 Background - Hydrodynamic cavitation methods: Important water treatment facilities for water disinfection purposes. - Hydrodynamic cavitation: fine bubble generation method used by physical hydrodynamic structures and pressure

3 Background - Hydrodynamic cavitation acts as a disinfectant => through 1) chemical mechanisms : Generation of OH radicals) and 2) physical mechanisms : Shock waves, Pressure gradients and Share forces).

4 Study Purposes - To establish an IS about methodology to evaluate the disinfection efficiency of fine bubbles, under conditions which are configured by ISO TC281, - To promote the relevant technology development and their industrial applications

5 Method 1 Test facility - Fine bubbles are generated by the test fine bubble cavitation unit in the test facility with the following characteristics: a 100L test tank: PVC with a methacrylate window, 50cm (diameter) ⅹ 70cm (height) a 6kW(220V, 60Hz) centrifugal multistage pump made of stainless steel PVC pipes (diameter: 32mm) and the test fine bubble cavitation unit Water flow rate: maximum 10ton/hr - The control test line is set without fine bubble cavitation to compare with the disinfection efficiency of test fine bubbles.

6 Method 1 - Hydrodynamic Cavitation - The capacity of the pump is appropriately fixed to circulate the bacterial test suspension within the test facility. - Test fine bubble cavitation unit shall be operated to produce fine bubbles.

7 Method 2 Test Bacteria & Bacterial test suspension - The bacterial activity shall be evaluated using following two test organisms: Escherichia coli ATCC ; Staphylococcus aureus ATCC The test tank and test facility should be cleaned by appropriate methods before the test. - Bacterial test suspension(n) : adjust the number of cells in the suspension to 1.5ⅹ10 8 cfu/ml to 5ⅹ10 8 cfu/ml using the diluent, estimating the numbers of units by any suitable means. Maintain this suspension in the water bath at 20 C±1 C and use within 2hr. The total amount of bacterial test suspension used is a 100 liters.

8 Method 3 - Experimental conditions - initial contact temperature and initial temperature of the bacterial test suspension: 20 C±1 C. - maximum contact temperature: if the contact temperature in the test tank is over 50 C±1 C, stop the test facility immediately, and take samples. The last recorded contact time at the final sampling shall be the last contact time. - contact time (operation time of the test facility) to be tested are 1min±10sec; 10min±10sec and 30min±10sec.

9 Method 3 - Experimental procedures - A total of 100 liters bacterial test suspension shall be moved to the test tank within 20min. - The produced fine bubbles shall be contacted the bacterial test suspension during the operation of the test facility => Test solution - Replicates of each test tube : 2 - Test: Test solution 9ml+ Interfering substance 1ml (20 C±1, 2min±10sec) => Test mixture 1ml+Neutralizer 8ml+ water 1ml (20 C±1, 5min±10sec) => Neutralizer mixture 1ml+Patri dishes(2) +TSA(12~15ml) => incubate(36 or37 C±1, 24hr) => Count

10 Method 4 - Experimental design Table 1. Test levels of microbubbles generated by HC (experimental temperature range is 20 C±1; initial water temperature of bacterial test solution is 20 C±1) size class of microbubbles (mean) test water with fine bubbles test water without fine bubbles Test Level Test Level Ⅰ Test Level Ⅱ (Control) description Test water generated by a fine bubble cavitation unit Test water without using fine bubble generator (i.e. the water circulation in the pipe generated turbulence can cause a potential decrease of the bacteria count)

11 Method 5 Calculation and results - only colony counts <300 cfu/ml & >15 cfu/ml - viable counts should be calculated using at least one pair of plates - For calculation of the weighted mean count in cfu/ml, use the following formula : c/(nⅹ10-1 ) where c : the sum of the colonies on all the plates taken into account n : the number of plates taken into account.

12 Method 5 Calculation and results For each test bacteria record the number of cfu/ml in the bacterial test suspension (N) and after the test procedure for bactericidal activity of the fine bubbles (N a ). The bactericidal activity of the test facility is expressed as reduction in viability: - Reduction in viability R = (N ⅹ 10-1 )/ N a - Relative Disinfection efficiency of the test fine bubble(d) =R/R c where R = the reduction in viability of test fine bubble mixture R c = the reduction in viability of the control test

13 Table 2. Relative Disinfection efficiency (D) of fine bubble test levels estimated by each test bacterial strain s disinfection test Test case Test Level Ⅰ Test bacteria Escherichia col i ATCC Staphylococcus aureus ATCC 6 538; Contact time 1 min±10sec 10min±10sec 30min±10sec R: D: R: D: R: D: R: D: R: D: R: D: Bacterial test suspension N: N: Test Level Ⅱ (Control) Escherichia col i ATCC Staphylococcus aureus ATCC 6 R c : R c : R c : R c : R c : R c : 538; N= number of cfu/ml of the bacterial test suspension; N a = number of cfu/ml in the test mixture; R= reduction in viability of test fine bubble mixture; R c = reduction in viability of the control test; D= disinfection efficiency of the test fine bubbles. N: N:

14 Table 3. Relative Disinfection efficiency (D) of fine bubble (mean size: 26.53±3.21 µm; No. concentration: 12,987±5321/l) test : Exp.1 Normal air- micro bubble Test case Test Level Ⅰ Test Level Ⅱ (Control) Test bacteria Escherichia col i ATCC Staphylococcus aureus ATCC 6 538; Escherichia col i ATCC Staphylococcus aureus ATCC 6 538; Contact time 1 min±10sec 10min±10sec 30min±10sec N a 1: 7.0*10 6 ; N a 2: 3.3*10 7 R: 4 D: 40.6 N a 1: 4.6*10 7 ; N a 2: 6.2*10 7 R: 1 D: 6.1 N a 1: 4.8*10 8 ; N a 2: 5.2*10 8 R c : 0 N a 1: 3.3*10 8 ; N a 2: 3.9*10 8 R c : 0 N a 1: 2.6*10 6 ; N a 2: 9.5*10 6 R: 11 D: N a 1: 1.5*10 7 ; N a 2: 4.1*10 7 R: 2 D: 15.3 N a 1: 4.9*10 8 ; N a 2: 5.0*10 8 R c : 0 N a 1: 2.8*10 8 ; N a 2: 4.3*10 8 R c : 0 N a 1: 2.0*10 6 ; N a : 8.7*10 6 R: 14 D: N a 1: 1.8*10 7 ; N a 2: 3.2*10 7 R: 2 D: 15.6 N a 1: 3.8*10 8 ; N a 2: 4.0*10 8 R c : 0 N a 1: 3.4*10 8 ; N a 2: 4.4*10 8 R c : 0 Bacterial test suspension N: 4.6*10 8 N: 2.2*10 8 N: 4.9*10 8 N: 4.0*10 8 N= number of cfu/ml of the bacterial test suspension; N a = number of cfu/ml in the test mixture; R= reduction in viability of test fine bubble mixture; R c = reduction in viability of the control test; D= relative disinfection efficiency of the test fine bubbles.

15 Table 4. Relative Disinfection efficiency (D) of fine bubble (mean size: 26.53±3.21 µm; No. concentration: 12,987±5321) test; Exp.2 Ozone(10g/hr) - micro bubble(* CD: Complete disinfection) Test case Test Level Ⅰ (Ozone-mic robubble) Test Level Ⅱ (Control : Just Ozone) Test bacteria Escherichia col i ATCC Staphylococcus aureus ATCC 6 538; Escherichia col i ATCC Staphylococcus aureus ATCC 6 538; Contact time 1 min±10sec 10min±10sec 30min±10sec N a 1: 4.4*10 6 ; N a 2: 3.4*10 6 R:14 D: 3.8 N a 1: 4.2*10 7 ; N a 2: 6.2*10 7 R:1 D: 1.2 N a 1: 1.2*10 8 ; N a 2: 1.6*10 8 R c :4 N a 1: 7.3*10 7 ; N a 2: 6.5*10 7 R c :1 N a 1: 2.9*10 5 ; N a 2: 1.5*10 5 R:263 D: 18.5 N a 1: 1.7*10 6 ; N a 2: 8.0*10 6 R:12 D: 6.4 N a 1: 9.5*10 6 ; N a 2: 2.1*10 6 R c :14 N a 1: 1.8*10 7 ; N a 2: 2.4*10 7 R c :2 N a 1: 0 ; N a 2: 0 R:*CD D:*CD N a 1: 4.4*10 5 ; N a 2: 7.1*10 5 R:64 D: 12.3 N a 1: 8.8*10 4 ; N a 2: 1.5*10 3 R c :17 N a 1: 6.4*10 6 ; N a 2: 9.4*10 6 R c :5 Bacterial test suspension N:5.2*10 8 N:3.5*10 8 N:4.9*10 8 N:4.0*10 8 N= number of cfu/ml of the bacterial test suspension; N a = number of cfu/ml in the test mixture; R= reduction in viability of test fine bubble mixture; R c = reduction in viability of the control test; D= disinfection efficiency of the test fine bubbles.

16 Application Test 1: Weate water of Slaughter house 미생물배양액

17 Application Test 2: Paint factory in Kuwait

18 Current status of the standardization of fine bubble tech. in Korea

19 Domestic Standardization of Korea Policy Projects ( 14~ 15) - Policy projects on Basic technology information & current tech. status - Development of national roadmap for standardization of fine bubble tech.( 15) Establishment of domestic Tech. Comm. on fine bubble tech,(iso/tc 281) ( 15) Korea Standard - Finebubble terminology & definition (KSL 1628) ( ) Establishment of Korea Fine Bubble Industry Association (KFBIA; )

20 Domestic Strategy of Standardization ( 15) Activation of fine bubble industry and research Establishment of on finebubble technolgy Support of international standardization activities Establishment of domestic verification system on finebubble tech.

21 3 rd ISO TC281 Plenary meeting in Jeju Island

22 KFBIA Organization structure (3.29, 2016) BOD (NWT, Ilsung, Sewon E&E, SB E&E, Pimax) President (NWT) Secretariat Consultants Technical Committee (10 experts) KS-Verification Center Envronmental Water Treatment C. Clean ing C. Agri/a quacul ture C. Med ical C. Mea sure men t C. Inter - Org aniz atio n C. Sem icon duct or C. R&D C.

23 Technical workshop: 3 times /yr