Author

Mohamed Shafi

Date of Award

5-2020

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Sulaiman Al-Zuhair

Second Advisor

Ashraf Aly Hassan

Third Advisor

Mette Hedegaard Thomsen

Abstract

Crude petroleum oil spills are among the most important organic contaminations, which result from uncontrolled releases and spillages during transportation or storage. The separated oils on that accumulate on top of the water can be removed by various conventional skimming methods. However, the emulsified portions that remain within the water phase are more difficult to remove and pose significant threats to the environment and could tamper the tertiary treatment in a wastewater treatment plant. Biological treatment, using bacteria, have proven to be an effective method in the removal of the emulsified oils. However, the biomass produced in this case does not have any significant remunerative value, and in most cases the used bacteria are pathogenic. In this work, microalgae have been proposed to be used, instead of bacteria, to combine the emulsified oil remediation with the microalgae potential as biofuel feedstock, which enhances the economic and environmental benefit of the process. A freshwater strain of Chlorella vulgaris was grown in water containing different concentrations of emulsified crude oil, up to 275 mg/L, at different temperatures. To enhance the removal of the emulsified oils, chemotrophic cultivation conditions was applied keeping the emulsified oils as a sole carbon source. The degradation was monitored by measuring the total organic carbon in the water. The specific growth rate of the microalgae at each initial oil concentration was determined and the results were fitted to a modified Monod kinetics model that takes specific interfacial area as the influential substrate, rather than the actual concentration. The microalgae growth was found to increase with the increase in temperature, in tested range, with μmax increasing from 1.17-1.48 day−1 as the temperature increased from 30oC and 40oC, and the activation energy was found to be 19.05 kJ/mol. However, the increase in the microalgae growth with temperature did not result increase on the oils removal and the yield of oil removal per biomass growth was found to decrease with the increase in temperature.

Comments

ﺗﻌﺪ اﻧﺴﻜﺎﺑﺎت اﻟﻨﻔﻂ اﻟﺨﺎم ﻣﻦ أھﻢ اﻟﻤﻠﻮﺛﺎت اﻟﻌﻀﻮﯾﺔ اﻟﺘﻲ ﺗﻨﺘﺞ ﻋﻦ اﻹطﻼﻗﺎت واﻻﻧﺴﻜﺎﺑﺎت اﻟﻐﯿﺮ ﻣﻨﻀﺒﻄﺔ أﺛﻨﺎء اﻟﻨﻘﻞ أو اﻟﺘﺨﺰﯾﻦ. ﯾﻤﻜﻦ إزاﻟﺔ اﻟﺰﯾﻮت اﻟﻤﻨﻔﺼﻠﺔ اﻟﺘﻲ ﺗﺘﺮاﻛﻢ ﻓﻮق اﻟﻤﺎء ﺑﻄﺮق ﺗﻘﻠﯿﺪﯾﺔ ﻣﺨﺘﻠﻔﺔ. وﻣﻊ ذﻟﻚ ، ﻓﺈن اﻷﺟﺰاء اﻟﻤﺴﺘﺤﻠﺒﺔ اﻟﺘﻲ ﺗﺒﻘﻰ ﻓﻲ طﻮر اﻟﻤﺎء ﺗﻜﻮن أﻛﺜﺮ ﺻﻌﻮﺑﺔ ﻓﻲ اﻹزاﻟﺔ وﺗﺸﻜﻞ ﺗﮭﺪﯾﺪات ﻛﺒﯿﺮة ﻋﻠﻰ اﻟﺒﯿﺌﺔ وﯾﻤﻜﻦ أن ﺗﺪﺧﻞ ﻓﻲ ﻣﺮﺣﻠﺔ اﻟﻌﻼج اﻟﺜﺎﻟﺚ ﻓﻲ ﻣﺤﻄﺔ ﻣﻌﺎﻟﺠﺔ ﻣﯿﺎه اﻟﺼﺮف اﻟﺼﺤﻲ. أﺛﺒﺖ اﻟﻌﻼج اﻟﺒﯿﻮﻟﻮﺟﻲ ، ﺑﺎﺳﺘﺨﺪام اﻟﺒﻜﺘﯿﺮﯾﺎ ، أﻧﮫ طﺮﯾﻘﺔ ﻓﻌﺎﻟﺔ ﻓﻲ إزاﻟﺔ اﻟﺰﯾﻮت اﻟﻤﺴﺘﺤﻠﺒﺔ. وﻣﻊ ذﻟﻚ ، ﻓﺈن اﻟﻜﺘﻠﺔ اﻟﺤﯿﻮﯾﺔ اﻟﻤﻨﺘﺠﺔ ﻓﻲ ھﺬه اﻟﺤﺎﻟﺔ ﻟﯿﺲ ﻟﮭﺎ أي ﻗﯿﻤﺔ ﻣﺠﺰﯾﺔ ﻛﺒﯿﺮة ، وﻓﻲ ﻣﻌﻈﻢ اﻟﺤﺎﻻت ﺗﻜﻮن اﻟﺒﻜﺘﯿﺮﯾﺎ اﻟﻤﺴﺘﺨﺪﻣﺔ ﻣﺴﺒﺒﺔ ﻟﻸﻣﺮاض. ﻓﻲ ھﺬا اﻟﻌﻤﻞ ، ﺗﻢ اﻗﺘﺮاح اﺳﺘﺨﺪام اﻟﻄﺤﺎﻟﺐ اﻟﺪﻗﯿﻘﺔ ، ﺑﺪﻻ ﻣﻦ اﻟﺒﻜﺘﯿﺮﯾﺎ ، ﻟﺪﻣﺞ ﻣﻌﺎﻟﺠﺔ اﻟﺰﯾﺖ اﻟﻤﺴﺘﺤﻠﺐ ﻣﻊ اﻟﻄﺤﺎﻟﺐ اﻟﺪﻗﯿﻘﺔ ﻛﻤﻮاد وﺳﯿﻄﺔ ﻟﻠﻮﻗﻮد اﻟﺤﯿﻮي ، ﻣﻤﺎ ﯾﻌﺰز اﻟﻔﺎﺋﺪة اﻻﻗﺘﺼﺎدﯾﺔ واﻟﺒﯿﺌﯿﺔ ﻟﻠﻌﻤﻠﯿﺔ. ﺗﻢ زرع ﺳﻼﻟﺔ ﻣﻦ اﻟﻤﯿﺎه اﻟﻌﺬﺑﺔ ﻣﻦ اﻟﻜﻠﻮرﯾﻼ اﻟﺸﺎﺋﻊ ﻓﻲ اﻟﻤﯿﺎه اﻟﺘﻲ ﺗﺤﺘﻮي ﻋﻠﻰ ﺗﺮﻛﯿﺰات ﻣﺨﺘﻠﻔﺔ ﻣﻦ اﻟﻨﻔﻂ اﻟﺨﺎم اﻟﻤﺴﺘﺤﻠﺐ ، ﺗﺼﻞ إﻟﻰ 275 ﻣﻠﻐﻢ/ﻟﺘﺮ ، ﻓﻲ درﺟﺎت ﺣﺮارة ﻣﺨﺘﻠﻔﺔ. ﻟﺘﻌﺰﯾﺰ إزاﻟﺔ اﻟﺰﯾﻮت اﻟﻤﺴﺘﺤﻠﺒﺔ ، ﺗﻢ ﺗﻄﺒﯿﻖ ﺷﺮوط اﻟﺰراﻋﺔ اﻟﻜﯿﻤﯿﺎﺋﯿﺔ ﻟﻠﺤﻔﺎظ ﻋﻠﻰ اﻟﺰﯾﻮت اﻟﻤﺴﺘﺤﻠﺒﺔ ﻛﻤﺼﺪر وﺣﯿﺪ ﻟﻠﻜﺮﺑﻮن. ﺗﻢ رﺻﺪ اﻟﺘﺤﻠﻞ ﺑﻘﯿﺎس إﺟﻤﺎﻟﻲ اﻟﻜﺮﺑﻮن اﻟﻌﻀﻮي ﻓﻲ اﻟﻤﺎء. ﺗﻢ ﺗﺤﺪﯾﺪ ﻣﻌﺪل اﻟﻨﻤﻮ اﻟﻤﺤﺪد ﻟﻠﻄﺤﺎﻟﺐ اﻟﺪﻗﯿﻘﺔ ﻓﻲ ﻛﻞ ﺗﺮﻛﯿﺰ زﯾﺖ أوﻟﻲ وﺗﻢ ﺗﺮﻛﯿﺐ اﻟﻨﺘﺎﺋﺞ ﻋﻠﻰ ﻧﻤﻮذج Monod اﻟﺤﺮﻛﻲ اﻟﻤﻌﺪل اﻟﺬي ﯾﺄﺧﺬ ﻣﻨﻄﻘﺔ ﺑﯿﻨﯿﺔ ﻣﺤﺪدة ﻛﺮﻛﯿﺰة ﻣﺆﺛﺮة ، ﺑﺪﻻ ﻣﻦ اﻟﺘﺮﻛﯿﺰ اﻟﻔﻌﻠﻲ. وﺟﺪ أن ﻧﻤﻮ اﻟﻄﺤﺎﻟﺐ اﻟﺪﻗﯿﻘﺔ ﯾﺰداد ﻣﻊ زﯾﺎدة درﺟﺔ اﻟﺤﺮارة ، ﻓﻲ اﻟﻨﻄﺎق اﻻﺧﺘﺒﺎري ، ﻣﻊ زﯾﺎدة maxµ ﻣﻦ 1.17 إﻟﻰ 1.48 ﻓﻲ اﻟﯿﻮم. ﺣﯿﺚ زادت درﺟﺔ اﻟﺤﺮارة ﻣﻦ 30 و 40 درﺟﺔ ﻣﺌﻮﯾﺔ ، ووﺟﺪت طﺎﻗﺔ اﻟﺘﻨﺸﯿﻂ ﺑﻤﻘﺪار 19.05 ﻛﯿﻠﻮﺟﻮل/ﻣﻮل. وﻣﻊ ذﻟﻚ ، ﻓﺈن اﻟﺰﯾﺎدة ﻓﻲ ﻧﻤﻮ اﻟﻄﺤﺎﻟﺐ اﻟﺪﻗﯿﻘﺔ ﻣﻊ درﺟﺔ اﻟﺤﺮارة ﻟﻢ ﯾﻨﺘﺞ ﻋﻨﮭﺎ زﯾﺎدة ﻓﻲ إزاﻟﺔ اﻟﺰﯾﻮت ووﺟﺪ أن ﻣﺤﺼﻮل إزاﻟﺔ اﻟﺰﯾﺖ ﻟﻜﻞ ﻧﻤﻮ ﻟﻠﻜﺘﻠﺔ اﻟﺤﯿﻮﯾﺔ ﯾﻨﺨﻔﺾ ﻣﻊ زﯾﺎدة درﺟﺔ اﻟﺤﺮارة.

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