From: PO2::"G.Malin@UEA.AC.UK" "Gill Malin" 25-MAR-1996 18:33:30.48 To: Multiple recipients of list ALGAE-L CC: Subj: Javex seawater sterilisation On the 15th March 1996 I posted the following to Algae-L: Some time back Brenda Bradford was involved in (maybe initiated) some algae-L correspondence which mentioned the use of JAVEX for sterilising large volumes of seawater. I would really appreciate some information about this technique, but have been unable to get through to her. Can anyone help? One of Brenda's colleagues kindly put me in contact with her (Brenda.Bradford@maritimes.dfo.ca) and she has detailed the technique in response to some of my questions. Several people replied expressing interest in the technique and Brenda kindly agreed that I could post her replies back to the list. If anyone can answer any of the questions posed please post your answers to algae-L. Many thanks to Brenda for sharing her expertise. Gill Malin. ************************************** Dr. Gill Malin School of Environmental Sciences University of East Anglia Norwich NR4 7TJ U.K. voice: 44 1603 592531 fax: 44 1603 507714 eMail: g.malin@uea.ac.uk ************************************** 1. What concentration is the sodium hypochlorite in the JAVEX and is it the only ingredient? Do you know if anything survives the treatment? Javex-12 is a the trade name of a type of bleach. It is supposed to be 10.8% W/W or 12.6% W/V Sodium Hypochlorite in a 3.6L container. (equivalent to 'Miltons' hypochlorite used by others?). As far as I know it is the only ingredient. I am pretty sure that at the concentrations I use it everything is killed. If I can elaborate for a moment, our water is pre-filtered to 1 micron and then goes through a UV light to kill most organisms before I add the bleach. In many places that would be sufficient but we have a blue-green alga and a pink corraline algae that survive the uv light and really make a mess of my culture containers so I add the bleach to eliminate them specifically. We also plate out (on marine agar) the water coming out of the uv light and nothing grows on the plates. 2. How much do you add to what volume of seawater and what is the pH of the seawater after addition? How long do you leave it? I've never considered a pH change with the added bleach because I'm assuming the sodium hypochlorite dissociaties into water and chlorine, however I measured the pH today to be sure. I add 100mls of the Javex-12 to 200L of water; again this is where my lack of chemistry shows because I do not know exactly how much chlorine I'm getting. I can read a water sample with a chlorine indicator very roughly (ie. a pool kit) and it varys anywhere from 3.5 to about 5 mg/L or ppm of chlorine. This variation is due to the age of the open bottle of Javex. After measuring the pH there was not a significant change; our ambient seawater has a pH of about 7.95 and the chlorinated water was about 8.32. I try to leave the water chlorinated for a minimum of 2 hours, but on a regular schedule of cleaning and starting new cultures the chlorinated water stands for about 22 hours before it is neutralized. 3. Is any precipitate formed at all? How much sodium thiosulphate is typically needed to neutralise? Do you use the water immediately? I have never noticed any precipitate. At present we are using a sodium thiosulphate working solution with a concentration of 150g/L; I add anywhere from 25 to 50mls of this solution to 200mls of chlorinated water depending again on the age of the bottle of javex. A 3.6 L bottle will last me about 6 weeks; when it is newly opened the chlorine content is quite strong and you have to use 50ml of sodium thio to neutralize. By the end of the 6 weeks 25-30mls of sodium thio usually does the trick. It is just a trial and error process; I try to use as little as possible. We have some colleagues who are going to try sodium sulphite instead of thiosulphate mainly because of the cost. It appears to be cheaper for the shellfish hatcheries which would use enormous quantities. Again I'm little rough on the chemistry here; I wish I knew how many moles of thio sulphate were needed to sufficiently neutralize the known quantity of moles of chlorine; perhaps someone over there could straighten me out. Any how, after adding the thio I bubble the water with air for about 5 minutes and then test the water with the pool kit for any signs of chlorine (which there should be none of). Then the water is ready to innoculate immediately after. I don't know what happens to the chlorine but I do know that bubbling helps speed up the neutralizing process by about 15 minutes. 4. What species of phytoplankton have you grown successfully in JAVEX treated seawater? I am currently growing 7 species of phytoplankton, all used by active shellfish hatcheries in NA. They are: 1. Tahitian isochrysis galbana 2. Pavlova lutheri 3. Chaetoceros calcitrans 4. Chaetoceros muelleri 5. Thalassiosira pseudonana 6. Skeletonema costatum 7. Nannochloropsis oculata All species grow equally well in javex treated water depending on the time of year. This is where my original question originated; there are certain times of the year when almost none of these species will grow whether the water is javex treated or autoclaved. However there are also times of the year when a species will not grow in javex treated water but will grow if the water is autoclaved. I am helpless to explain why and apparently so is everyone else. You just have to plan your species culture accordingly.