Monitoring and disinfection of biofilm-associated sulfate reducing bacteria on different substrata in a simulated recirculating cooling tower system

Microbial biofilm and corrosion in cooling systems are the most common problems that damage expensive equipment, cause loss of production, and increase maintenance costs. Sulfate reducing bacteria were considered the major bacterial group involved in microbiologically influenced corrosion (MIC). We investigated the survival and enumeration of biofilm-associated SRB on coupons of galvanized steel, stainless steel, and copper, which are materials used in the manufacturing of cooling systems. We also investigated the effect of monochloromine on SRB as in mixed species mature biofilms formed on coupons by simulating recirculating cooling water conditions, due to the better penetration feature in biofilms than the residual chlorine. It was concluded that SRB count increased with time in bulk water and the surfaces (P < 0.01). Experimental results supported by statistical analyses show that monochloromine is poorly effective on SRB colonies formed on galvanized and stainless steel surfaces

Effect of Methyl jasmonate treatment on antioxidant capacity, internal quality and postharvest life of raspberry fruit

Native population of raspberry fruits (Rubus spp) were treated with Methyl Jasmonate (MJ) fumigation and were assayed for the antioxidant capacity, total anthocyanins and postharvest quality after 7 days storage at 4?C. The result of experiment revealed that berries treated with methyl jasmonate (MJ) showed higher antioxidant capacity and total anthocyanins compared to the controled ones (non-treated). Decay incidence was reduced in fumigated fruits during storage at 4?C, which resulted to long postharvest life (as indicated by fugal decay) compared to the controled ones. Total soluble solid, titratable acidity and pH were influenced by storage periods. Therefore, MJ treatments could not suppress the declining, which happened during storage time. In conclusion, although raspberry fruits treated with MJ maintained higher levels of antioxidant capacity, total anthocyanins compared to untreated fruits during storage, but because of high perishable, MJ treated fruits could not maintain significant changes in internal quality

The use of nano/micro-layers, self-healing and slow release coatings to prevent corrosion and biofouling

The mitigation of corrosion and biofouling is a challenge. Through application of chemicals and special techniques can slow these undesired processes, an effective resolution requires a multidisciplinary approach involving scientists, engineers, and metallurgists. In order to understand the importance of the use of nano- and microlayers as well as self-healing coatings, the basic concepts of corrosion, corrosion mechanisms, corrosion inhibition and the microbiologically influenced corrosion will be summarised. The preparation, characterization and application of Langmuir-Blodgett and self assembled nanolayers in corrosive and microbial environment will be discussed. Preparation and characterization of microcapsules/ microspheres and their application in coatings will be demonstrated by a number of examples

MIC and Cracking of Mild and Stainless Steels

Microbiologically influenced corrosion (MIC) is basically an electrochemical corrosion in which the extent and severity of the corrosion process is determined by organisms such as, but not limited to, bacteria. This work will discuss both electrochemical and mechanical features of MIC of three types of steels of frequent use, that is, mild, stainless and duplex stainless steels. The bacteria investigated in this study are single-type cultures of marine isolates of sulphate reducing bacteria, iron reducing bacteria as well as their mixed cultures. This is important because in nature, it is the impact of mixed communities of bacteria that can affect corrosion of engineering materials. Also, to the best knowledge of this author, for the first time the stress corrosion cracking of these steels in biotic cultures containing these bacteria have been characterised and compared with abiotic environments. In conducting this research, techniques such as SSRT (for conducting mechanical tests), OCP (as one of the safest electrochemical methods for studying MIC) as well as XRD, EDXA and metallography have been employed