Optimization of Temperature and Inoculum Size for Phycoremediation of Paddy-Soaked Rice Mill Wastewater
01 Jan 2020-Journal of Environmental Engineering (American Society of Civil Engineers (ASCE))-Vol. 146, Iss: 1, pp 04019091
TL;DR: In this article, microalgae is used as a sustainable treatment system by integrating the wastewater treatment with bioenergy recovery, transforming this technology to real-time, but it is difficult to implement in practice.
Abstract: Phycoremediation encompasses microalgae as a sustainable treatment system by integrating the wastewater treatment with bioenergy recovery. However, transforming this technology to real time...
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TL;DR: In this article, the selected microalgae (Chlorella pyrenoidosa) was cultured in paddy-soaked wastewater (PWW) using outdoor raceway ponds of 50 L capacity where biotransformation of nutrients (NH3−N removal: 75.89±−0.69); PO4−P removal: 73.71±− 0.75%; yield co-efficient YN: 6.56−±-0.
Abstract: Sustainable resources management, incorporating energy markets and resources such as electricity, fossil fuels, renewable and sustainable energy capital is essential for society to understand production and conversion of various forms of energy, their current as well as future supply. Waste-to-energy (WTE) or energy-from-waste (EFW) is a well-identified transitional technology which could prevent complete depletion of renewable resources. In our present study, the selected microalgae (Chlorella pyrenoidosa) was cultured in paddy-soaked wastewater (PWW) using outdoor raceway ponds of 50 L capacity where biotransformation of nutrients (NH3–N removal: 75.89 ± 0.69%; PO4–P removal: 73.71 ± 0.75%; yield co-efficient YN: 6.12 mg biomass/mg of N; YP: 7.77 mg biomass/mg P) has occurred with better growth and biochemical composition (dry biomass weight: 1.56 ± 0.11 g/L; chlorophyll: 15.57 ± 0.14 mg/L; specific growth rate (SGR): 0.42/d; lipids: 27.47 ± 1.41% biomass; carbohydrates: 23.77 ± 1.00% and protein: 46.12 ± 3.55%). Further, the obtained algal lipid was identified for a wide range of fatty acid methyl esters (FAME) and consequently brought forward to in-situ single-step transesterification by optimizing reaction conditions. Central composite design (CCD) of response surface methodology (RSM) has given optimized conditions of sample amount: 2 g (wet); methanol sulphuric acid volume: 3 mL; and hexane volume: 4 mL, under the reaction temperature of 90 °C for maximum biodiesel conversion (46.54% of algal lipids). The outcome of our current research may add value to the application and development of WTE technology for sustainable energy conservation.
14 citations
01 Feb 2021
TL;DR: The results demonstrate the potential of CO2 and HCO3 −1 in control the CCM pathways, thus, another step in the development of the photobioreactor design.
Abstract: A step to net-zero of carbon dioxide losses in the microalgae cultivation process was targeted in the current study. This research was carried out by using pre-dissolved inorganic carbon (DIC) as a source of carbon with two doses of twenty-five and fifty millilitres. C. sorokiniana MH923013, Coelastrella MH923011 and Coelastrella MH923012 strains were used in the present investigation. The experimental data emphasized the direct influence of carbonic solution on microalgal growth according to the fast adaption of algal cells and higher productivity compared to control and dilution cultures. It was observed that microalgae strains conduct a corresponding response associated with different dosing of the saturated carbonic solution. For instance, dosing of 50 ml carbon dioxide revealed fast performance to reach the stationary phase (23-25) day with clear growth improvement. In addition, 0.1633 day−1 as a maximum specific growth rate in the exponential phase was recorded with this dosing. While as there was another obvious growth enhancement with supplying 25 ml CO2 solution, but reached the stable phase after around (37-42) day from inoculation with a maximum specific growth rate 0.0987 day−1. These results demonstrate the potential of CO2 and HCO3 −1 in control the CCM pathways, thus, another step in the development of the photobioreactor design.
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TL;DR: In this paper, the authors showed that the soak water of the cold-soaking method followed in conventional rice mills showed a relatively higher population of total aerobic bacteria, staphylococci, lactic acid bacteria and yeasts than the other methods, and biochemical oxygen demand (BOD) of this soak water was also high.
28 citations
TL;DR: The present N management practice of N topdressing 5 to 7 d before VPI coincided with PI for short duration IR50 but not for later maturing IR42, which reduced the spikelet number in IR50 and more so in IR42 where preflowering spikelet abortion started even before spikelet development was completed.
Abstract: Identification of growth stages and cultivar differences are necessary to develop efficient N fertilizer management for lowland rice (L.). To help characterize growth stages an electron microscope was used to identify different panicle development stages, cultivar growth differences, and potential yield loss periods. Varieties IR50 (90-d maturity) and IR42 (120-d maturity) were grown at the International Rice Research Institute during the 1987 wet season. Thirteen morphologically different development stages up to floral organ development were identified. Between cultivars, duration of each development stage varied. Necknode differentiation was defined as physiological panicle initiation (PI) and observed at growth stage (GS) 1.8 occurring 35 days after seeding (DAS) in IR50 and at GS 1.10 (49 DAS) in IR42. Visual panicle initiation (VPI) was observed at GS 1.9 (42 DAS) in IR50 and at GS 1.11 (64 DAS) in IR42. Panicle development took 15 to 18 d (4–7 d for panicle branches) in IR50 and 24 to 31 d (11–15 d for panicle branches) in IR42. Therefore the present N management practice of N topdressing 5 to 7 d before VPI coincided with PI for short duration IR50 but not for later maturing IR42. Preflowering and post flowering spikelet abortion reduced the spikelet number in IR50 and more so in IR42 where preflowering spikelet abortion started even before spikelet development was completed. Comprehensive N timing studies based on rice apical development stages are required for improving N efficiency and increasing rice yields.
26 citations
TL;DR: S. obliquus exhibited different responses to potential grazing pressure under different intensities of competition, i.e., Scenedesmus morphological response to grazing infochemicals was affected by competition against Microcystis.
Abstract: The green alga Scenedesmus is known for its phenotypic plasticity in response to grazing risk. However, the benefits of colony formation induced by infochemicals from zooplankton should come with costs. That is, a tradeoff in benefit-to-cost ratios is likely under complex environmental conditions. In this study, we hypothesized that the coexistence of Scenedesmus and its competitors decreases the formation of anti-grazer colonies in Scenedesmus. Results demonstrated that the presence of a competitor Microcystis aeruginosa inhibited inducible defensive colony formation of Scenedesmus obliquus and the established defensive colonies negatively affected the competitive ability of S. obliquus. The proportion of induced defensive colonies in cultures was dependent on the relative abundance of competitors. Under low competition intensity, large amount of eight-celled colonies were formed but at the cost of decreased competitive inhibition on M. aeruginosa. By contrast, defensive colony formation of S. obliquus slacked in the presence of high competition intensity to maintain a high displacement rate (competitive ability). In conclusion, S. obliquus exhibited different responses to potential grazing pressure under different intensities of competition, i.e., Scenedesmus morphological response to grazing infochemicals was affected by competition against Microcystis.
26 citations
TL;DR: In this article, the preparation of adsorbents from rice husk ash for the efficient treatment of rice mill wastewater has been discussed, and the maximum chemical oxygen demand (COD) removal was observed at adsorbent dose 10g/L, pH 5 and 120min.
25 citations
TL;DR: The results indicate the suitability of microalgae cultivation in rice mill effluent treatment for nutrient removal.
Abstract: Microalgae are product of sustainable development owing to its ability to treat variety of wastewater effluents and thus produced biomass can serve as value added product for various commercial applications. This paper deals with the cultivation of microalgae species namely Chlorella pyrenoidosa and Scenedesmus abundans in rice mill effluent (i.e., paddy soaked water) for nutrient removal. In order to investigate the nutrient removal capability, microalgae are subjected to cultivation in both raw and autoclaved samples. The maximum phosphate removal by Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 98.3% and 97.6%, respectively, whereas, the removal of ammoniacal nitrogen by Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 92% and 90.3%, respectively. The growth (measured in terms of chlorophyll content) of Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 3.88 mg/l and 5.55 mg/l, respectively. The results indicate the suitability of microalgae cultivation ...
25 citations