ارزيابي توليد بيوگاز از هضم بي هوازي حالت خشك لجن فاضلاب شهري

Evaluation of Biogas Production from Solid State Anaerobic Digestion of Municipal Sewage Sludge

ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ اﻓﺰاﯾﺶ ﻣﺼﺮف ﺳﻮﺧﺖﻫﺎي ﻓﺴﯿﻠﯽ در ﺟﻬﺎن، ﻫﻤﭽﻨﯿﻦ اﻓﺰاﯾﺶ ﻗﯿﻤﺖ و اﺛﺮات زﯾﺴﺖ ﻣﺤﯿﻄﯽ آنﻫﺎ، اﻣﺮوزه ﻧﯿﺎز و ﻋﻼﻗﻪ ﺑﻪ ﺟﺎﯾﮕﺰﯾﻨﯽ آنﻫﺎ ﺑﺎ ﻣﻨﺎﺑﻊ ﺟﺪﯾﺪ و ﺗﺠﺪﯾﺪﭘﺬﯾﺮ اﻧﺮژي زﯾﺎد ﺷﺪه اﺳﺖ. ﯾﮑﯽ از ﻣﻨﺎﺑﻊ اﻧﺮژي ﺗﺠﺪﯾﺪﭘﺬﯾﺮ ﺑﯿﻮﮔﺎز اﺳﺖ و ﻫﻀﻢ ﺑﯽﻫﻮازي ﯾﮑﯽ از روشﻫﺎي ﺗﻮﻟﯿﺪ ﺑﯿﻮﮔﺎز از ﻣﻮاد آﻟﯽ اﺳﺖ ﮐﻪ روز ﺑﻪ روز در ﺣﺎل ﮔﺴﺘﺮش ﻣﯽﺑﺎﺷﺪ. ﯾﮑﯽ از ﺗﻘﺴﯿﻢﺑﻨﺪيﻫﺎي ﻫﻀﻢ ﺑﯽﻫﻮازي ﺣﺎﻟﺖ ﻣﺎﯾﻊ و ﺣﺎﻟﺖ ﺧﺸﮏ اﺳﺖ. ﺑﺮﺧﯽ از ﻣﺰاﯾﺎي ﻫﻀﻢ ﺑﯽﻫﻮازي ﺣﺎﻟﺖ ﺟﺎﻣﺪ ﺷﺎﻣﻞ ﺣﺠﻢ ﮐﻤﺘﺮ ﻣﻮرد ﻧﯿﺎز رآﮐﺘﻮر، اﻧﺮژي ﮐﻤﺘﺮ ﺑﺮاي ﮔﺮمﮐﺮدن و ﺟﺎﺑﺠﺎﯾﯽ راﺣﺖﺗﺮ اﺳﺖ. در اﯾﻦ ﭘﮋوﻫﺶ ﻫﻀﻢ ﺑﯽﻫﻮازي ﺣﺎﻟﺖ ﺟﺎﻣﺪ ﻟﺠﻦ ﻓﺎﺿﻼب ﺷﻬﺮي ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻗﺮار ﮔﺮﻓﺖ. ﻣﻄﺎﻟﻌﻪ در ﻣﻘﯿﺎس آزﻣﺎﯾﺸﮕﺎﻫﯽ )ﺣﺠﻢ 1 ﻟﯿﺘﺮ(، دﻣﺎي ﻣﺰوﻓﯿﻠﯿﮏ )37 درﺟﻪ ﺳﺎﻧﺘﯽﮔﺮاد( و ﺳﻬﻢ ﻣﻮاد ﺟﺎﻣﺪ 20% اﻧﺠﺎم ﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ارزﯾﺎﺑﯽ ﺧﺼﻮﺻﯿﺎت ﻟﺠﻦ ﻓﺎﺿﻼب ﺷﻬﺮي ﻧﺸﺎن داد اﯾﻦ ﻣﻮاد از ﭘﺘﺎﻧﺴﯿﻞ ﺧﻮﺑﯽ ﺑﺮاي ﺗﻮﻟﯿﺪ ﺑﯿﻮﮔﺎز از ﻫﻀﻢ ﺑﯽﻫﻮازي ﺣﺎﻟﺖ ﺟﺎﻣﺪ ﺑﺮﺧﻮردارﻧﺪ )ﺳﻬﻢ ﻣﻮاد ﺟﺎﻣﺪ ﮐﻞ 25/7%، ﺳﻬﻢ ﻣﻮاد ﺟﺎﻣﺪ ﻓﺮار 50/7% و ﻧﺴﺒﺖ ﮐﺮﺑﻦ ﺑﻪازت 11/7(. ﻫﻢﭼﻨﯿﻦ ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از ﻫﻀﻢ ﺑﯽﻫﻮازي ﻧﺸﺎن داد ﻣﻘﺪار 362 ﻣﯿﻠﯽﻟﯿﺘﺮ ﺑﯿﻮﮔﺎز ﺑﻪازاي ﻫﺮ ﮔﺮم ﻣﻮاد ﺟﺎﻣﺪ ﻓﺮار در ﺷﺮاﯾﻂ ﻧﺮﻣﺎل آزﻣﺎﯾﺸﮕﺎﻫﯽ ﺑﻪدﺳﺖ آﻣﺪ. از اﯾﻦ ﻣﯿﺰان 213 ﻣﯿﻠﯽﻟﯿﺘﺮ ﻣﺘﺎن ﺣﺎﺻﻞ ﺷﺪ ﮐﻪ ﻣﻌﺎدل 58/8% اﺳﺖ. ﻫﻢﭼﻨﯿﻦ ﻣﯿﺰان درﺻﺪ ﮐﺎﻫﺶ ﻣﻮاد ﺟﺎﻣﺪ ﻓﺮار ﮐﻪ ﯾﮑﯽ از ﭘﺎراﻣﺘﺮﻫﺎي ﺑﻬﺮهوري آزﻣﺎﯾﺶ اﺳﺖ 63/7% ﺑﻪدﺳﺖ آﻣﺪ.

Due to the increasing consumption of fossil fuels in the world as well as their increasing cost and environmental impacts, the great need and interest to replace them with renewable energy resources has increased. Anaerobic digestion is a biochemical process that is able to convert almost all kinds of multi-dimensional biodegradable organic matters under anaerobic conditions to biogas. According to water content, anaerobic digestion methods are classified as wet and solid state. The solid-state anaerobic digestion has been claimed to be advantageous over liquid AD for a number of reasons including smaller reactor volume, lower energy requirements for heating and minimal material handling. In this paper, biogas production from solid state anaerobic digestion of municipal sewage sludge was studied. A series of single-stage batch mesophilic (37 ± 1oC) anaerobic digestions were performed at a total solids concentration of 20% in 1 liter reactor volume. The evaluation of municipal sewage sludge characteristics showed that this substrate has a good potential for solid state anaerobic digestion (Total solids, volatile solids and C/N ratio were obtained 25.7%, 50.7% and 11.7, respectively). The biogas yield was achieved 362 ml/g VS, which methane content of biogas was 213 ml (58.8%). The volatile solids reduction, a significant parameter to measure productivity of anaerobic digestion, was obtained to be 63.7%.