Return to search

Greenalgae as a substrate for biogas production - cultivation and biogas potentials

<p>Algae is regarded as a good potential substrate for biogas production, due to high cells productivity, low cellulose and zero lignin content. Two parts were included in this study: first, cultivations of micro-algae (<em>Chlorella sorokiniana</em> and <em>Tetraselmis suecica</em>) at two different nitrate concentrations, also the effect of addition of CO<sub>2</sub> on algae grow was investigated in this first part. Second, batch fermentations of the cultivated micro-algae as well as a powder <em>Chlorella</em> (obtained from Raw Food Shop) and a dry mix filamentous algae (collected in the pounds in the park at the back of the Tema-building and then dried) were performed. In this part also effects of thermo-lime pretreatment (room temperature, 80<sup>o</sup>C, 105<sup>o</sup>C and 120<sup>o</sup>C) on the algae biogas potentials was investigated.</p><p> </p><p>Both strains of micro-algae cultured at low nitrate gave more CH<sub>4</sub> yield: 319 (±26) mL and 258 (±12) mL CH<sub>4 </sub>per added gVS was obtained during the degradation of <em>Chlorella sorokiniana </em>grown at 0.4mM-N and 2mM-N level, respectively. For<em> Tetraselmis suecica</em> 337 (±37) mL and 236 (±20) mL CH<sub>4</sub> per added gVS was obtained at 2.4mM-N and 12mM-N level, respectively. Powder <em>Chlorella</em> gave the highest biogas production (719 ±53 mL/added gVS) and CH<sub>4</sub> yields (392 ±14 mL/added gVS), followed by the dry filamentou<em>s</em> algae (661 ±20 mL biogas and 295 ±9 mL CH<sub>4</sub> per added gVS) and <em>Tetraselmis suecica</em> (12 mM-N; 584 ±7 mL biogas and 295 ±9 mL CH<sub>4</sub> per added gVS).</p><p> </p><p>A negative effect of lime treatment at room temperature on CH<sub>4</sub> yield of algal biomass was obtained. Lime treatment at 120<sup>o</sup>C showed the fastest degradation rate for <em>Tetraselmis</em> <em>suecica </em>and powder <em>Chlorella</em> during the initial 5 days of incubation.  </p><p> </p><p><em>Chlorella sorokiniana</em> and <em>Tetraselmis suecica</em> cultures flushed with biogas containing 70% and also CO<sub>2</sub> enriched air (5% CO<sub>2</sub>) did not increase cells growth (measured as OD<sub>600</sub>) if compared to references grown under air. On the contrary, a clearly inhibition effect on the algal cells growth was observed in some cultures.</p>

Identiferoai:union.ndltd.org:UPSALLA/oai:DiVA.org:liu-57987
Date January 2010
CreatorsLiu, Yang
PublisherLinköping University, Linköping University, Department of Water and Environmental Studies
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeStudent thesis, text

Page generated in 0.0015 seconds