Effect of hydrodynamics, light and nitrogen stresses on biomass growth and lipid productivity in an airlift reactor

The quality of biodiesel strongly depends on the proportion of saturated and unsaturated fatty acids in lipids. Thus, various process parameters and strategies which affect the lipid's composition are also studied in this article. Microalgae sp. Scenedesmus abundance was grown in two identical airlift photobioreactors (PBRs) equipped with red and white light LEDs of 10 L capacity. The effects of hydrodynamics stress (by manipulating the gas velocity) and nitrogen stress (nitrate concentration) have been studying on the biomass growth and lipid productivity. It has been found that the algae cells growth in the airlift PBR equipped with red LEDs were higher than that obtained in the PBR with white LEDs. The total lipids (dry wt. basis) of microalgae sp. were 12% (±2.4) and 17% (±1.9) for white-LED-PBR and red-LED-PBR respectively for nitrate replete media. Whereas, it was obtained 18% (±1.8) and 23% (±2.5) in the case of nitrate deplete media for white-LED-PBR and red-LED-PBR respectively. The lipid profiling in the case of nitrate deplete condition showed that the SFA, MUFA and PUFA contents were obtained in the range of 28-30%, 35-53% and 10-31% respectively with CN values ranging between 51-53 which are suitable characteristics for biodiesel production

Mixotrophic cultivation of microalgae to enhance the quality of lipid for biodiesel application: effects of scale of cultivation and light spectrum on reduction of α-linolenic acid

The research on microalgal biodiesel is focused not only on getting the highest lipid productivity but also desired quality of lipid. The experiments were initially conducted on flask scale (1L) using acetate carbon source at different concentrations viz. 0.5, 2, 3 and 4 g L− 1. The optimum concentration of acetate was considered for further experiments in two airlift photobioreactors (10 L) equipped separately with red and white LED lights. The Feasibility Index (FI) was derived to analyze the scalability of mixotrophic cultivation based on net carbon fixation in biomass per consumption of total organic carbon. The experimental strategy under mixotrophic mode of cultivation lowered the α-linolenic acid content of lipid by 60–80% as compared to autotrophic cultivation for Scenedesmus abundans species and yielded the highest biomass and lipid productivities, 59 ± 2 and 17 ± 1.8 mg L− 1 day−1, respectively. The TOC, nitrate, and phosphate reduction rates were 74.6 ± 3.0, 11.5 ± 1.4, 9.6 ± 2.4 mg L− 1 day− 1, respectively. The significant change was observed in lipid compositions due to the scale, mode of cultivation, and light spectra. As compared to phototrophic cultivation, biodiesel obtained under mixotrophic cultivation only met standard biodiesel properties. The FI data showed that the mixotrophic cultivation was feasible on moderate concentrations of acetate (2–3 g L− 1)

An integrated approach for microalgae cultivation using raw and anaerobic digested wastewaters from food processing industry

An integrated approach has been proposed to produce microalgal biodiesel using both raw wastewater (RW) and anaerobically digested wastewater (ADW) of food processing industry without addition of extra nutrients or carbon source for cultivation besides obtaining effluent discharge permissible limits of TN, TP, and COD. Three microalgae species cultivated with following different combinations: RW, ADW, RW+ADW, and glucose+ADW. Results indicated that the addition of RW as a carbon source in ADW significantly enhanced BP, LP, and TN removal as compared to the ADW alone. The runs with RW+ADW removed COD, TN, and TP by 89%, 84%, and 70%, respectively. Sc. obliquus showed highest biomass and lipid productivities (211 and 27.5 mg L−1 d−1) for RW+ADW. The addition of RW or glucose in ADW significantly lowered PUFA contents to 5–15% CDW (as against 35–50% with ADW) for Chl. sorokiniana and Sc. obliquus

Cauda equina syndrome after spinal anaesthesia in a patient with asymptomatic tubercular arachnoiditis

A 14-year-old boy underwent emergency debridement surgery of right foot under spinal anaesthesia. Four hours after the surgery, the patient developed symptoms of cauda equina syndrome (CES). Postoperative magnetic resonance imaging of the patient's spine suggested underlying tubercular arachnoiditis. The boy was started on intravenous methylprednisolone and antitubercular therapy. He responded to the therapy and recovered completely in 2 weeks without any residual neurological deficits. We suggest that underlying pathological changes in the subarachnoid space due to tubercular arachnoiditis contributed to maldistribution of the local anaesthetic drug leading to CES

Bioremediation of synthetic high–chemical oxygen demand wastewater using microalgal species Chlorella pyrenoidosa

The microalgal species Chlorella pyrenoidosa was cultivated in synthetic wastewater of initialchemical oxygen demand (COD), nitrate, and phosphate concentrations of 5000, 100, and 40 mg/L,respectively. The aim of the study was to find out the tolerance of microalgae to different COD concentrations and the extent of COD degradation at those concentrations. Three dilutions of wastewater (initial COD concentrations 5000, 3000, and 1000 mg/L) and three inoculum sizes (0.1,0.2, and 0.3 g/L) were considered for the study. The experimental parameters such as total organic carbon, total inorganic carbon, COD, optical density, total solids, nitrate, and phosphate were measured on a daily basis. Biodegradation kinetics was determined for all cases using first-order reaction and Monod degradation equations. Optimal results showed that up to 90% reduction in TOC was obtained for 1000 COD wastewater while only 38% reduction in total organic carbon (TOC)was achieved for 5000 COD wastewater. Over 95% reduction in nitrate and nearly 90% removal of phosphate were obtained with the lowest microalgal inoculum concentration (i.e., 0.1 g/L) for all COD dilutions. This study showed that microalgal species C. pyrenoidosa can successfully degrade the organic carbon source (i.e., acetate) with significant removal efficiencies for nitrate and phosphate

Microalgal bioremediation of food-processing industrial wastewater under mixotrophic conditions: Kinetics and scaleup approach

The Chlorella microalgae were mixotrophically cultivated in an unsterilized and unfiltered raw foodprocessing industrial wastewater. Both inorganic carbon (CO2-air) and organic carbon (wastewater) were provided simultaneously for microalgae growth. The aim of the study is to find out the utilization rates of total organic carbon (TOC) and chemical oxygen demand (COD) under mixotrophic conditions for a given waste water. About 90% reduction in TOC and COD were obtained for all dilutions of wastewater. Over 60% of nitrate and 40% of phosphate were consumed by microalgae from concentrated raw wastewater. This study shows that microalgae can use both organic and inorganic sources of carbon in more or less quantity under mixotrophic conditions. The growth of microalgae in food-processing industrial wastewater with all studied dilution factors, viz. zero (raw), 1.6 (dilution A), and 5 (dilution B) suggests that the freshwater requirement could be reduced substantially (20%–60%). The degradation kinetics also suggests that the microalgae cultivation on a high COD wastewater is feasible and scalable

Outdoor microalgae cultivation in airlift photobioreactor at high irradiance and temperature conditions: effect of batch and fed-batch strategies, photoinhibition, and temperature stress

The microalgae Scenedesmus abundans cultivated in five identical airlift photobioreactors (PBRs) in batch and fed-batch modes at the outdoor tropical condition. The microalgae strain S. abundans was found to tolerate high temperature (35–45 °C) and high light intensity (770–1690 μmol m− 2 s− 1). The highest biomass productivities were 152.5–162.5 mg L− 1 day− 1 for fed-batch strategy. The biomass productivity was drastically reduced due to photoinhibition effect at a culture temperature of > 45 °C. The lipid compositions showed fatty acids mainly in the form of saturated and monounsaturated fatty acids (> 80%) in all PBRs with Cetane number more than 51. The fed-batch strategies efficiently produced higher biomass and lipid productivities at harsh outdoor conditions. Furthermore, the microalgae also accumulated omega-3 fatty acid (C18:3) up to 14% (w/w) of total fatty acid at given outdoor condition

Ozone Induced Biodegradability Enhancement and Colour Reduction of a Complex Pharmaceutical Effluent

The treatment of a complex pharmaceutical effluent using a combination of ozonation and biological treatment is reported with the use of ozonation as a preand posttreatment. Pretreatment facilitated biodegradability index (BI = BOD/COD) enhancement of up to 0.44 along with COD and color reduction of up to 42% and 33%, respectively. Subsequent anaerobic biodegradation of effluent indicated negligible biogas generation; however, aerobic biodegradation of pretreated effluent resulted in COD reduction (73%) and color reduction (62%), which was also indicated by the biokinetic parameters. Further, ozonation as a posttreatment led to higher overall COD (87%) and color (93%) removal

Prevention of Parent to Child Transmission (PPTCT) program data in India: an emerging data set for appraising the HIV epidemic.

BACKGROUND: Evidence based resource allocation and decentralized planning of an effective HIV/AIDS response requires reliable information on levels and trends of HIV at national and sub-national geographic levels. HIV sentinel surveillance data from antenatal clinics (HSS-ANC) has been an important data source to assess the HIV/AIDS epidemic in India, but has a number of limitations. We assess the value of Prevention of Parent to Child Transmission (PPTCT) programme data to appraise the HIV epidemic in India. METHODS/FINDINGS: HIV data from PPTCT sites were compared to HSS-ANC and general population level surveys at various geographic levels in the states of Karnataka, Maharashtra and Andhra Pradesh. Chi-square tests were used to ascertain statistical significance. PPTCT HIV prevalence was significantly lower than HSS-ANC HIV prevalence (0.92% vs. 1.22% in Andhra Pradesh, 0.65% vs. 0.89% in Karnataka, 0.52% vs. 0.60% in Maharashtra, p<0.001 for all three states). In all three states, HIV prevalence from PPTCT centres that were part of the sentinel surveillance was comparable to HSS-ANC prevalence but significantly higher than PPTCT centres that were not part of the sentinel surveillance. HIV prevalence from PPTCT data was comparable to that from general population surveys. In all three states, significant declines in HIV prevalence between 2007 and 2010 were observed with the PPTCT data set. District level analyses of HIV trends and sub-district level analysis of HIV prevalence were possible using the PPTCT and not the HSS-ANC data sets. CONCLUSION: HIV prevalence from PPTCT may be a better proxy for general population prevalence than HSS-ANC. PPTCT data allow for analysis of HIV prevalence and trends at smaller geographic units, which is important for decentralized planning of HIV/AIDS programming. With further improvements to the system, India could replace its HSS-ANC with PPTCT programme data for surveillance