Gıda fermantasyon sektöründen kaynaklanan koku emisyonlarının biyofiltre sistemi kullanılarak giderilmesi
Treatment of odor emissions from food fermentation process by using biofilter system
Yazar: MERVE YILMAZ
Danışman: PROF. DR. KADİR ALP
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı / Çevre Bilimleri ve Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Çevre Mühendisliği = Environmental Engineering

Özet:
Koku, gelişen endüstriyel faaliyetler ile birlikte hava kirliliğinin artması ve özellikle sanayi bölgesi yakınlarında yaşayan insanlarda hava kalitesi bilincinin oluşmaya başlaması itibariyle çevresel sorunlarda kirletici bir parametre olarak kabul edilmektedir. Koku kirliliği oluşturan başlıca bileşiklerden sayılan uçucu organik bileşikler (UOB) atmosferik ozon oluşumuna sebebiyet vermeleri, oksidasyon ürünleri ile sera gazlarının olumsuz etkilerine katkı sağlamaları gibi çevresel problemler oluşturmalarının yanında insan sağlığı için de tehlikeli olan kimyasallardır. 
Bulundukları bölgelerde oldukça şikayet edilen tesisler olan gıda fermentasyon tesislerini temsilen örnek bir maya üretim tesisinin emisyonu incelenmiştir. Hacimsel olarak toplam atıkgaz emisyonu 65.000 m3/sa olan tesiste analitik ölçüm yöntemiyle emisyon karakterizasyonu yapılarak proses salınımının pik noktasında temsil edici kirletici bileşen olan etanol konsantrasyonunun 800 mg/m3 olduğu görülmüştür.
Gaz numunelerinin alınmasında 20:35 Tenax-TA™, 60:80 Carboxen™ 1000 ve 60:80 Carbosieve™ SIII malzemelerini içeren sorbent tüpler kulanılmış, analiz için TD/GC-MS yöntemi kullanılmıştır. Ayrıca tesiste akredite bir laboratuvar tarafından olfaktometrik ölçüm gerçekleştirilmiş ve koku konsantrasyonu yaklaşık olarak 40.000 KB/m3 olarak tespit edilmiştir. 
Koku kirleticilerinin giderimi konusunda geçmişten bu yana farklı teknolojilere sahip yöntemler geliştirilmiştir. Bu yöntemler, fizikokimyasal ve biyolojik prosesler olmak üzere temelde iki gruba ayrılmaktadır. Fizikokimyasal yöntemler; adsorpsiyon, absorpsiyon, yoğuşma, kimyasal yıkayıcılar, termal oksidasyon, katalitik oksidasyon ve ozonlama sistemleri olmak üzere farklı teknolojilere sahip prosesleri içermektedir. 
Biyolojik yöntemler ise kirleticilerin mikrobiyal faaliyetlerle giderilmesi temeline dayanan biyofiltreler, biyoyıkayıcılar, biyodamlatmalı filtreler, aktif çamur difüzyon sistemleri ve memban biyoreaktör alt gruplarına ayrılmaktadır. Etkin bir kirlilik giderimi sağlayabilmek amacıyla kirletici emisyon karakteristiğine dikkat edilmesi gerekmektedir. Atıkgaz debisi, kirletici konsantrasyonu, kirleticilerin sudaki çözünürlükleri ve biyobozunabilirlikleri gibi özelliklere dikkat edilerek uygun kontrol yöntemi seçilmelidir. 
Bu prosesin arıtma ihtiyacına cevap verecek pilot ölçekli bir biyofiltre sistemi tasarlanmış ve işletime alınmıştır. Biyofiltre sistemleri ile atıkgaz arıtımı, atıkgaz içerisindeki koku bileşiklerinin filtre görevi gören bir dolgu malzemesi içerisinde mikrobiyal yolla bozunmalarına dayanmaktadır. Biyofiltre performansını incelemek amacıyla; boş yatak bekletme süresi, yüzey yükleme hızı, kütle transfer hızı, giderim verimi ve giderim kapasitesi parametreleri izlenmiştir. 
Dolgulu kolonda 100 s bekletme süresi öngörüsüyle işletime alınan sistem sürekli olarak çalıştırılmıştır. Başlangıçtan itibaren 200-400-800 mg/m3 atıkgaz konsantrasyon koşulları için sistemin giderim verimi (sırasıyla %96,81 - %95,19 - %90,50) ve giderim kapasitesi (sırasıyla 10,70 - 13,91 - 22,46 g/m3∙sa) belirlenmiştir. 
Sistemin giderim kapasitesinin sınırlarını tespit edebilmek amacıyla kütle transfer testi yapılmıştır. Atıkgaz konsantrasyonu 800 mg/m3'ten 1600 mg/m3'e çıkarıldığında sistemin giderim kapasitesinin de iki katına çıktığı gözlenmiştir.

Abstract:
Odor is regarded as an environmental pollution parameter by increasing air pollution with developing industrial activities and acquiring the awareness of public especially living around the industrial areas about air quality.  
The levels of odor pollution arising from industrial plants vary by raw materials used in process and process types such as petroleum refineries, petroleum chemicals industry, coke production, foundry, paper manufacturing, plastics industry, surface coating and painting treatments, dry cleaning, fertilizer production, vegetable oil production, pharmaceutical industry, detergent production, tobacco and cigarette production, sugar production, waste inciniration, waste disposal (landfill, composting etc.), transportation superstructure activities (asphalt coating etc.), tire production, wastewater and sludge treatment, farming, meat and bone processing, fishing and fish processing and food processes (coffee roasting, canned food industry, rendering processes, processes based on fermentation, baking products etc.). 
Besides, the units of facility that are odor emission source may be different from each other according to activity field of facilities. Chimneys, storage spaces, wastewater lines, wastewater collection and treatment units and production units where especially anaerobic reactions occur at the facilities are the main units for industrial odor pollution.  
Odor measurement is actualised by defining of odor sense with specific dimensions which are classified as objective and subjective. To determinate odor limits and control to odor pollution, the required objective parameter is odor concentration. 
Bread, cheese, yogurt, sour cream, vinegar, juice, beer, wine etc. products are produced through biochemical reactions called fermentation by bacteria and fungal species and these products are referred to as fermented foods. Fermentation steps in the fermented food production process cause to odor problems by emiting many volatile organic compounds and the other gases to environmental air. Especially in beer, wine, bread and yeast production processes, anaerobic activity of Saccharomyces cerevisiae named ferment species on polysaccharide molecules resultant intense alcohol emission may cause odor nuisance. In addition to ethanol and acetaldehyde, other alcohols such as 2,3-bütadiol, butanol, and isopropyl alcohol, organic acids and acetate compounds also are subject to odor emissions, but these compounds are observed at very low concentrations when compared with ethanol and acetaldehyde compounds. 
Emissions of a yeast manufacturing plant were analyzed to represent food fermentation process because of getting complaints about the facility from nearby settlement. When the waste gas emission (total waste gas emissions by volume per an hour is 65.000 m3/h) was characterized by anaytical measurement method, ethanol concentration being representative pollutant for process was found roughly 800 mg/m3 at time of the peak of process emissions. The fermentation process wastegas emission contains by 70-75% ethanol, 25-30% and ≤5% acetone and other volatile organic materials, such as propanol. 
The main odor substances emitted into the atmosphere are organic and inorganic sulfur compounds (hydrogen sulfide (H2S), methyl mercaptan (CH3SH), dimethyl sulphide (CH3)2S and dimethyl disulfide (CH3)2S2), organic and inorganic nitrogen compounds (ammonia (NH3) and amine groups of compounds) and the volatiles organic compounds (aromatic, aliphatic and chlorinated hydrocarbons, saturated acids, alcohols, aldehydes, terpenes and ketones). 
Volatile organic compounds (VOCs) are the main compounds that bring about the odor pollution and VOCs creates several environmental problems like causing the formation of atmospheric ozone, contributing to the adverse effects of greenhaouse gases by their oxidation products. In addition, these chemicals are accepted as hazardous air pollutans (HAPs) for human health. 
In Turkey, specific compounds released from specific facilities which causes air pollution are limited with "Regulation on Control of Industrial Air Pollution" enacted by 03.07.2009 dated and 27277 numbered Official Gazette, but this regulation doesn't involve any commands about the odor nuisance that air releasing compounds create. Because the relevant regulation can not answer to odor complaints, new regulations were needed for measurement and controlling of odor pollution. Therefore, "Regulation on Control of Emissions that Contribute to Odor (KOEKHY)" dated July 19, 2013 is enacted. This regulation contains procedures and sanctions related to determination and solution of odor problems from the activities leading to odor complaints. 
After the determination of the odor pollution, the topic of odor pollution controlling comes to the fore. Different methods with different technologies have been developed from past to present to remove odor pollutants. These methods are basically divided into two groups, physicochemical and biological processes. Physico-chemical methods include adsorption, absorption, condensation, chemical scrubbing, thermal oxidation, catalytic oxidation and ozonation systems with different technologies. Biological methods are based on removal of contaminants by microbial activities and these methods are divided into biofilters, bioscrubbers, biotrickling filters, activated sludge diffusion systems and memrane bioreactor sub-groups. In order to provide an effective removal must be considered pollutant emission characteristics. The suitable controlling method should be selected according to several features such as wastegas flow rate, pollutant concentration, water solubility and biodegradability of contaminants. 
Biological odor controlling methods are more environmentally friendly and sustainable methods when compared with physicochemical methods used from past to present. These biological methods has been widely used in the industry and has been a topic for relevant researches. Besides, industrial-scale applications of biological treatment processes are increasing due to stable and durable performances of them under ambient temperature and pressure conditions and they can be established with relevant costs. 
Wastegas treatment with biofilter system is based on the microbial degradation of the odor compounds in a packing material serves to filter. In order to perform an effective treatment in the biofilter system, optimal conditions should be provided. 
Therefore, loading rate, empty bed residence time, packing material, type of microorganisms, oxygen and nutrient contents, moisture, temperature, pH and pressure drop parameters are very important for designing of biofilter system. In order to examine the performance of pilot scale biofilter; empty bed residence time, surface loading rate, mass transfer rate, removal efficiency and removal capacity parameters were monitored. 
Based on EPA Compendium Method TO-17 "Determination of Volatile Organic Compounds in Ambient Air Using Active Sampling Onto Sorbent Tubes", 20:35 Tenax-TA™, 60:80 Carboxen™ 1000, and 60:80 Carbosieve™ SIII containing multisorbent tubes and TD/GC-MS method were used for gas sampling and analysing. Also, dynamic olfactometry analysis were conducted in facility by an accredited laboratory based on TS-EN 13725:2004 "Air quality. 
Determination of odour concentration by dynamic olfactometry" standard and odor concentration was detected approximately 40,000 OU/m3. A pilot scale biofilter system was designed and set into operation to fulfill the treatment need of food fermentation process. The biofilter system was operated continuously with 100 s. residence time in packed column. 
The treatment efficiencies for 200-400-800 mg/m3 waste gas inlet concentration conditions were respectively %96.81 - %95.19 - %90.50. The elimination capacities for the same conditions were respectively 10.70 - 13.91 - 22.46 g/m3∙h. To determine the limits of biofilter system's elimination capacity, the mass transfer test was conducted by increasing waste gas inlet concentration from 800 mg/m3 to 1600 mg/m3 and doubling the elimination capacity was observed.