Sasikaladevi Rathinavelu

Bio: Sasikaladevi Rathinavelu is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Bioreactor & Coffee wastewater. The author has co-authored 1 publications.

Self-directing optimization for enhanced caffeine degradation in synthetic coffee wastewater using induced cells of Pseudomonas sp.: Bioreactor studies

Abstract: Coffee wastewater poses a serious threat to the environment due to the presence of a large number of toxic compounds which necessitates the importance of developing suitable treatment methodologies. Although there are treatments available to treat the different wastewaters, the presence of caffeine in wastewater interrupts the complete treatment of coffee wastewater. Alternatively, Pseudomonas sp. showed an excellent capacity to withstand coffee wastewater and degrades caffeine completely in shake flask studies. In this study, we scaled up the coffee wastewater treatment to a 1 L in bioreactor and optimized for caffeine degradation using the self-directing optimization technique. Using self-directing optimization maximum degradation rate of 16.73 mg/L.h was obtained at 210 rpm, 1.16 vvm, and 0.383 g/L of initial biomass. A regression model was developed to predict the caffeine degradation rate with oxygen mass transfer coefficient (kLa) and initial biomass concentration. The regression model was solved and the optimal conditions of initial biomass concentration and kLa are 0.23 g/L and 64.26 h−1 respectively. Under those conditions, experiments were performed and maximum degradation rate was 16.9 mg/L.h was obtained, which is in comparison with model prediction (15.2 mg/L.h).

Identification of microbial communities and their removal efficiency of multiple pharmaceutical micropollutants combined in Membrane-Bioreactors

Abstract: Pharmaceuticals are of concern to our planet and health as they can accumulate in the environment. The impact of these biologically active compounds on ecosystems is hard to predict and information on their biodegradation is necessary to establish sound risk assessment. Microbial communities are promising candidates for the biodegradation of pharmaceuticals such as ibuprofen, but little is known yet about their degradation-capacity of multiple micropollutants at higher concentrations (100 mg/L). In this work, microbial communities were cultivated in lab-scale Membrane Bioreactors (MBRs) exposed to increasing concentrations of a mixture of six micropollutants (ibuprofen, diclofenac, enalapril, caffeine, atenolol, paracetamol). Key players of biodegradation were identified using a combinatorial approach of 16S rRNA sequencing and analytics. Microbial community structure changed with increasing pharmaceutical intake (from 1 mg/L to 100 mg/L) and reached a steady-state during incubation for 7 weeks on 100 mg/L. HPLC analysis revealed a fluctuating but significant degradation (30-100%) of five pollutants (caffeine, paracetamol, ibuprofen, atenolol, enalapril) by an established and stable microbial community mainly composed of Achromobacter, Cupriavidus, Pseudomonas and Leucobacter. By using the microbial community from MBR1 as inoculum for further batch culture experiments on single micropollutants (400 mg/L substrate, respectively), different active microbial consortia were obtained for each single micropollutant. Microbial genera potentially responsible for degradation of the respective micropollutant were identified, i.e. Pseudomonas sp. and Sphingobacterium sp. for ibuprofen, caffeine and paracetamol, Sphingomonas sp. for atenolol, and Klebsiella sp. for enalapril. Our study demonstrates the feasibility of cultivating stable microbial communities capable of degrading simultaneously a mixture of highly concentrated pharmaceuticals in lab-scale MBRs and the identification of microbial genera potentially responsible for the degradation of specific pollutants. Graphical abstract

Optimization by uniform design U8(83) approach for enhanced caffeine degradation in synthetic wastewater in bioreactor

Abstract: Coffee wastewater contains large amounts of caffeine which affects microflora and seed development to great extent. Although several physio‐chemical methods available for caffeine degradation, they are not preferred for large‐scale treatment. In this study, we optimized induced cell concentration, aeration and agitation rate for maximizing caffeine degradation rate in bioreactor using Uniform design. Maximum caffeine degradation rate of 23·59 mg L−1 h−1 was achieved. The reduction in chemical oxygen demand, biological oxygen demand and total organic carbon removal were found to be 72, 78 and 72% respectively. Mathematical model was developed through regression analysis and predicted maximum caffeine degradation rate of 24·2 mg L−1 h−1 under optimal conditions of 0·35 g L−1 biomass, 395 rev min−1 and 1·62 vvm. Experimental validation at optimum condition resulted in 22 mg L−1 h−1 of caffeine degradation rate. This is the first‐ever bioreactor study showing highest caffeine degradation rate in synthetic coffee wastewater with limited experimental runs.