طراحي سامانه هاي مناسب تصفيه فاضلاب در صنايع توليد ورق هاي فشرده چوبي

Appropriate System Design of Wastewater Treatment Plants for Wood Panel Industries

ﺳﺎﺑﻘﻪ و ﻫﺪف: اﻧﺘﺨﺎب ﻣﻨﺎﺳﺐ ﺳﺎﻣﺎﻧﻪﻫﺎي ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼب، ﯾﮑﯽ از ﻣﻬﻢ ﺗﺮﯾﻦ ﺑﺨﺶﻫﺎي ﻃﺮاﺣﯽ ﺗﺼﻔﯿﻪﺧﺎﻧﻪ ﺷﻬﺮي و ﺻﻨﻌﺘﯽ اﺳﺖ. ﻃﺮاﺣﺎن ﻋﻤﻮﻣﺎً ﺑﺎ اﺳﺘﻔﺎده از ﺗﺠﺮﺑﯿﺎت ﺷﺨﺼﯽ و ﻓﻨﺎوريﻫﺎي ﻣﻮﺟﻮد اﻗﺪام ﺑﻪ ﻃﺮاﺣﯽ ﺳﯿﺴﺘﻢﻫﺎي ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼب ﻣﯽ ﮐﻨﻨﺪ. ﺷﺒﺎﻫﺖ ﺳﯿﺴﺘﻢﻫﺎي ﺗﺼﻔﯿﻪﺧﺎﻧﻪ ﺷﻬﺮي ﺑﺎ ﺑﺮﺧﯽ از ﺳﯿﺴﺘﻢﻫﺎي ﺻﻨﻌﺘﯽ، ﻣﻨﺠﺮ ﺑﻪ ﮐﺎﻫﺶ اﺳﺘﻔﺎده و ارزﯾﺎﺑﯽ ﺳﯿﺴﺘﻢ ﻫﺎي ﻣﺨﺘﻠﻒ ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼب و اﻧﻌﻄﺎفﭘﺬﯾﺮي آن ﺷﺪه اﺳﺖ. ﻫﺮ ﭼﻨﺪ ﻓﺮاﯾﻨﺪ ﺗﻮﻟﯿﺪ ورقﻫﺎي ﻓﺸﺮده ﭼﻮﺑﯽ ﻣﻌﻤﻮﻻً ﻓﺮاﯾﻨﺪ ﺧﺸﮏ اﺳﺖ، وﻟﯽ ﺣﺠﻢ آب ﻣﺼﺮﻓﯽ در ﺑﺨﺶ ﺷﺴﺘﺸﻮي ﭼﯿﭙﺲ، ﭘﺎﻻﯾﺶﮔﺮ، دﯾﮓﻫﺎي ﺑﺨﺎر و ﺧﺸﮏ ﮐﻦ ﻣﯽﺗﻮاﻧﺪ ﻗﺎﺑﻞ ﻣﻼﺣﻈﻪ ﺑﺎﺷﺪ. وﺟﻮد ﭼﺴﺐ اوره ﻓﺮمآﻟﺪﻫﯿﺪ، ﻣﻮاد اﺳﺘﺨﺮاﺟﯽ ﭼﻮﺑﯽ، اﻟﯿﺎف و ﺗﺮﮐﯿﺒﺎت ﻟﯿﮕﻨﯿﻨﯽ در ﻓﺎﺿﻼب ﺻﻨﺎﯾﻊ ﺗﻮﻟﯿﺪ ورقﻫﺎي ﻓﺸﺮده ﭼﻮﺑﯽ و اﺳﺘﻘﺮار اﯾﻦ ﺻﻨﺎﯾﻊ در ﻣﻨﺎﻃﻖ ﻣﺨﺘﻠﻒ ﺷﻬﺮي، ﮐﺸﺎورزي و ﺷﻬﺮك ﻫﺎي ﺻﻨﻌﺘﯽ، ﻃﺮاﺣﯽ ﺑﻬﯿﻨﻪ ﺳﯿﺴﺘﻢ ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼب آن ﻫﺎ را ﺿﺮوري ﺳﺎﺧﺘﻪ اﺳﺖ. در اﯾﻦ ﻣﻘﺎﻟﻪ ﺳﻌﯽ ﺷﺪه اﺳﺖ ﺗﺎ ﺳﺎﻣﺎﻧﻪ ﻫﺎي ﻣﺨﺘﻠﻒ ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼب ﺻﻨﺎﯾﻊ ﺗﻮﻟﯿﺪ ورقﻫﺎي ﻓﺸﺮده ﭼﻮﺑﯽ ﺑﺮرﺳﯽ ﺷﻮد ﺗﺎ ﺻﺎﺣﺒﺎن اﯾﻦ ﺻﻨﺎﯾﻊ ﺑﺘﻮاﻧﻨﺪ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﯿﺎز و ﻗﻮاﻧﯿﻦ زﯾﺴﺖ ﻣﺤﯿﻄﯽ ﻣﻨﻄﻘﻪ ﺧﻮد، ﺳﺎﻣﺎﻧﻪ ﺗﺼﻔﯿﻪ ﺧﺎﻧﻪ ﻣﻨﺎﺳﺐ را اﻧﺘﺨﺎب ﮐﻨﻨﺪ. ﻣﻮاد و روش ﻫﺎ: اﯾﻦ ﻣﻘﺎﻟﻪ ﻣﺮوري ﺑﺮ روشﻫﺎي ﮐﺎرﺑﺮدي ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼب ﮐﺎرﺧﺎﻧﺠﺎت ﺻﻨﺎﯾﻊ ﺳﻠﻮﻟﺰي از ﻃﺮﯾﻖ ﻣﻄﺎﻟﻌﺎت ﻣﻮردي و ﮐﺘﺎﺑﺨﺎﻧﻪ اي را ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار داده اﺳﺖ. ﯾﺎﻓﺘﻪ ﻫﺎ: ﺑﺮ اﺳﺎس ﯾﺎﻓﺘﻪﻫﺎي ﺑﻪ دﺳﺖ آﻣﺪه، ﺑﺨﺸﯽ از ﺗﺮﮐﯿﺒﺎت ﻓﺮم آﻟﺪﻫﯿﺪ ﺑﻪ ﻣﺘﺎﻧﻮل ﺗﺒﺪﯾﻞ ﻣﯽ ﺷﻮد. ﺗﻤﺎﻣﯽ ﺳﻮﺑﺴﺘﺮاي COD زﻣﺎﻧﯽ ﮐﻪ ﻓﺮم آﻟﺪﻫﯿﺪ ﺑﻪ ﻣﻘﺪار mg/l.COD 200-600 ﺑﺎﺷﺪ، ﺗﺒﺪﯾﻞ ﺑﻪ ﻣﺘﺎن ﻣﯽ ﺷﻮد؛ اﻣﺎ در ﻣﻘﺪار mg/l.COD 1400 ﻫﯿﭻ ﻣﺘﺎﻧﯽ ﺑﻪ دﻟﯿﻞ اﺛﺮ ﺳﻤﯽ ﻓﺮم آﻟﺪﻫﯿﺪ در واﮐﻨﺶ ﺗﻮﻟﯿﺪ ﻧﺸﺪه اﺳﺖ. ﺑﺎ اﯾﻦ وﺟﻮد، ﺗﺒﺪﯾﻞ ﻓﺮم آﻟﺪﻫﯿﺪ ﺑﻪ ﻣﺘﺎن ﺑﺎزدارﻧﺪه ﻓﺮآﯾﻨﺪ ﻧﯿﺴﺖ. ﻃﯽ ﺗﺒﺪﯾﻞ ﻓﺮم آﻟﺪﻫﯿﺪ، ﯾﮏ ﭘﯿﮏ ﻫﯿﺪروژن ﻣﺸﺎﻫﺪه ﻣﯽ ﺷﻮد ﮐﻪ اﯾﻦ ﭘﯿﮏ ﻣﺮﺑﻮط ﺑﻪ ﻣﻘﺪار اوﻟﯿﻪ ﻓﺮم آﻟﺪﻫﯿﺪ ﻣﯽ ﺑﺎﺷﺪ. ﺑﻪ ﻧﻈﺮ ﻣﯽ رﺳﺪ ﮐﻪ ﻓﺮم آﻟﺪﻫﯿﺪ اﺑﺘﺪا اﮐﺴﯿﺪ ﻣﯽ ﺷﻮد و ﺳﭙﺲ ﺑﻪ ﻣﺘﺎﻧﻮل ﮐﺎﻫﺶ ﻣﯽ ﯾﺎﺑﺪ. ﻧﺘﯿﺠﻪ ﮔﯿﺮي: ﺑﻬﺘﺮﯾﻦ ﻣﻮرد ﺑﺮاي ﺗﺼﻔﯿﻪ ﻓﺎﺿﻼبﻫﺎي ﺣﺎوي ﻓﺮمآﻟﺪﻫﯿﺪ و اوره، ﺗﺮﮐﯿﺐ واﺣﺪﻫﺎي ﻧﯿﺘﺮوژندار و ﻧﯿﺘﺮوژن زدا در ﯾﮏ ﺷﮑﻞ ﭘﯿﺶﻧﯿﺘﺮوژنزدا ﻣﯽﺑﺎﺷﺪ. در ﺗﺎﻧﮏ ﻧﯿﺘﺮوژنزدا، ﻧﯿﺘﺮات ﺑﺮﮔﺸﺘﯽ از واﺣﺪ ﻧﯿﺘﺮوژنزدا، ﺑﻪ وﺳﯿﻠﻪ ﻓﺮم آﻟﺪﻫﯿﺪ ﺑﻪﻋﻨﻮان اﻟﮑﺘﺮونﮔﯿﺮﻧﺪه، ﻧﯿﺘﺮوژنزداﯾﯽ ﺷﺪه و اوره ﻫﻢ ﺑﻪ آﻣﻮﻧﯿﺎك ﻫﯿﺪروﻟﯿﺰ ﻣﯽﺷﻮد. در واﺣﺪ ﻧﯿﺘﺮوژن دار، آﻣﻮﻧﯿﺎك و ﻓﺮم آﻟﺪﻫﯿﺪ ﺑﺎﻗﯽﻣﺎﻧﺪه ﺑﻪ ﻧﯿﺘﺮﯾﺖ و دياﮐﺴﯿﺪ ﮐﺮﺑﻦ اﮐﺴﯿﺪ ﻣﯽﺷﻮﻧﺪ.

Background and Objectives: Selecting appropriate system design of wastewater treatment plants (WWTPs) is one of the most important parts for municipal and industrial WWTPs. Professionals often design a wastewater treatment system based on their personal experiences and technologies availability. The industrial wastewater system resembling to some municipal systems led to reduce analyzing and flexibility of different WWTPs. Although, wood panels are produced at dry processes, but water utilization for chips washing, refining, boiler, and dryer are noticeable. The wastewater generated by the wood panel industries contain urea formaldehyde, wood extractives, fiber and lignin compounds. These compounds and location of these industries at urban, agricultural, and industrial park areas led to necessity of optimal wastewater treatment designing for them. This study attempts to investigate different configurations of WWTPs for wood panel industries in order to help the decision makers to choose the suitable system based on their needs and environmental regulations. Materials and Methods: This paper reviewed the applicable methodologies of wastewater treatment from cellulosic industries through case studies and literature review. Results: Based on the observations, some parts of formaldehyde convert to methanol. All COD substrate will be converted to methanol when formaldehyde amount is 200-600 mg/l.COD; but methanol is not produced if formaldehyde amount is 1400 mg/l.COD because of formaldehyde poisonous effect. However, conversion of formaldehyde to methanol is not process inhibitor. During the process, hydrogen peak observed that it related to the amount of initial formaldehyde. It seems that formaldehyde initially oxidize and then reduce to methanol. Conclusion: Best option for wastewater treatment plant for wastewater containing formaldehyde and urea is combining nitrogen and dinitrogen units in a pre-dinitrogen process. In dinitrogen tank, the nitrate from dinitrogen process is dinitrated by formaldehyde as electron acceptor and urea hydrolysis to ammonia. In anoxic reactor, remaining ammonia and formaldehyde is oxided to nitrite and carbon dioxide.