ABSTRACT
Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed.
Subject(s)
Corrosion , Construction Materials/microbiology , Environmental Microbiology , Acids/metabolismABSTRACT
The conversion of waste cooking oil into riboflavin by Ashbya gossypii was investigated in this paper. The effect of initial pH and the original volume of added waste cooking oil in the medium were evaluated to optimize the fermentation efficiency. The results show that when the initial pH was adjusted to 6.5 and 40 g/L waste cooking oil was added in the medium, no residual waste cooking oil was observed and the riboflavin yield reached 4.78 g/L. During the fermentation process, pH, biomass, free amino nitrogen and reduced sugar were dynamically monitored to evaluate the efficient utilization of waste cooking oil for riboflavin yield. The results show that when pH was kept in the range of 6.5-6.8 during the fermentation process, the levels of free amino nitrogen and reduced sugar could be used more efficiently and the riboflavin yield increased to 6.76 g/L .
A conversão microbiana de óleo de cozinha recolhido em riboflavina por Ashbya gossypii foi investigada nesse estudo. O efeito inicial do pH e o volume original de óleo de cozinha recolhido foram avaliados para otimizar a eficiência de fermentação. Os resultados mostraram que quando o pH inicial foi ajustado para 6.5 e 0g/l de óleo de cozinha adicionado ao meio, nenhum óleo residual foi observado e a riboflavina pura atingiu 4.78g/L. Durante o processo de fermentação, pH, biomassa, amino nitrogênio livre e açúcar reduzido foram monitorados dinamicamente para avaliar a utilização eficiente do óleo de cozinha recolhido por riboflavina. Os resultados mostram que quando o pH é mantido numa amplitude de 6.5-6-8 durante o processo de fermentação, os níveis de amino nitrogênio livres e açúcar reduzido podem ser usados mais eficientemente e a riboflavina pura chega a 6.76 g/L.