Food Waste/Odor Treatment Technologies PDF

Lecture 5- FDSC585 FOOD WASTE / ODOR TREATMENT TECHNOLOGIES I hope everybody is SAFE and SOUND  What is the source of odors in Food waste? Control of odor removal and air pollution in Food Industry / wastewater treatment plants has become critical because of the negative impacts of...

Lecture 5- FDSC585 FOOD WASTE / ODOR TREATMENT TECHNOLOGIES I hope everybody is SAFE and SOUND  What is the source of odors in Food waste? Control of odor removal and air pollution in Food Industry / wastewater treatment plants has become critical because of the negative impacts of invasive pollutants that are no longer limited to the working environment of treatment plants, but extend to nearby residential areas.  Waste treatment Plant  MSW plant  Biogas Plant  Food Industries  Background The biological treatment of municipal wastewater is typically based on the so- called activated sludge process. Most odor problems occur in the collection system, in primary treatment facilities and in solids handling facilities. In most instances, the odors associated with collection systems and primary treatment facilities are generated as a result of an anaerobic or “septic” condition. This condition occurs when the oxygen transfer to the wastewater is limited  Background In the anaerobic state, the microbes present in the wastewater have no dissolved oxygen available for respiration. This allows the microbes known as “sulfate- reducing bacteria” to thrive. These bacteria utilize the sulfate ion (SO4-) that is naturally abundant in most waters as an oxygen source for respiration. The byproduct of this activity is hydrogen sulfide (H2S). This byproduct has low solubility in the wastewater and a strong, offensive, rotten-egg odor.  Background Solids handling facilities are another significant problem area connected with odor. In biosolids dewatering and treatment processes, the biosolids commonly undergo extreme turbulence, pH adjustment and/or thermal treatment. Depending on the nature of the biosolids stream and the treatment used, the odor compounds released can consist of any combination of the following compounds in a wide range of concentrations: Ammonia (NH3), Amines, HYDROGEN SULFIDE, Organic sulfides Mercaptans.  Background A range of technologies is available to treat the odorous air aspired from confined sections at Food Plants /Wastewater treatment plants and sludge handling facilities. These can be classified according to the main process involved in the odor removal. Biochemical: biofilters, bioscrubbers, Chemical: scrubbers catalytic oxidation, ozonation; Physical: adsorption (activated carbon), absorption (clean water scrubbers).  Background Waste gases from industry have traditionally been treated using the physicochemical processes. However the biological methods of odor treatment are widely applied in Europe and are increasing the USA, owing to their efficiency, cost-effectiveness, and environmental acceptability. The advantage of the biological treatments over physicochemical techniques relies on reduction of the operating costs. Among other biochemical technologies, the biofilters offer simpler operations and maintenance, with very limited use of chemicals and with the main operational cost related to the replacement of the biofilter media (once every 2–5 years). BIOFILTER  BIOFILTER A biofilter is simply a bed of organic material (media) with a suitable porosity, allowing for air passage, humidity trapping and biomass growth. As the foul air passes upward through the media, the odor causing compounds are adsorbed onto a film of water and microbes developed on the organic material. BIOFILTER  BIOFILTER These microbes then convert the adsorbed compounds by oxidizing them to carbon dioxide, water and inorganic salts. The biofilter is a self-regulating ecosystem, and is therefore likely to function for long time, without excessive control.  BIOFILTER A typical biofilter has the following basic constructed components: 1) the containment 2) the biofilter media, 3) the humidifier and wetting systems, 4) biofilter air diffusion system 5) the air ducts and fans BIOFILTER  BIOFILTER Design of Biofilter-Sizing Empty Bed Residence Time (EBRT) –EBRT required depends on the odorous compound (s) and type of media. A = surface area of biofilter D = depth Q = flowrate  BIOFILTER Design of Biofilter-Sizing Empty Bed Residence Time (EBRT) EBRTs below 60 seconds usually resulted in poor performance, while those above 60 seconds generally performed well. Further sampling and measurement of the exhaust from these biofilters revealed that approximately 20 seconds of EBCT was required to remove H2S (hydrogen sulfide), while the other 40 seconds were required to remove the volatile organic compounds (VOCs) in the inlet air.  BIOFILTER Design of Biofilter-Media Selection Types of media –soil: long life, relatively low loading rates –organic: replacement 2 to 5 years, higher loading rates –synthetic: usually component of mix, site specific  BIOFILTER Design of Biofilter-Media Selection Successful biofilter requires careful: –Media selection –Moisture control –Airflow distribution  BIOFILTER Performance Data for Organic Biofilter  BIOFILTER ODOR UNITS (OU) When measuring odor with an olfactometer, panelists are exposed to the odor sample via the dilution unit of the olfactometer. Initially, the odor is highly diluted, all panelists indicate that they cannot smell it. What is an odor unit? By definition, the point at which 50% of the panelists cannot smell the odor but 50% can, is called the PERCEPTION THRESHOLD and is equal to 1 odor unit per cubic meter.  BIOFILTER ODOR UNITS (OU) To find out how many odor units the sample had in the first place, the operator – once the perception threshold has been reached – adds up all the dilutions that were required to reach that threshold. Example: if the sample was diluted, say, 647 times, in order to reach 1 odor unit, then the sample odor concentration was 647 odor units (o.u./m3), initially.  BIOTRICKLING FILTER The BIOFILTER odor treatment method aims to biologically treat the of odor- causing gases such as Ammonia (NH3), H2S, and other volatile organic compounds (VOC's). The Biotrickling Filter method of treatment is more thorough treatment method that use chemical methods for odor treatment BIOTRICKLING FILTER  BIOTRICKLING FILTER NH3 Scrubber System The base gets to be neutralized with an acidic scrubber (H2SO4),and, thus, it gets removed before the biological treatment which doesn't efficiently remove NH3 Saturating the remaining gas with water (increasing humidity) before the biological treatment step. This step removes potential dust and microsolids, thus, prolonging the life of the packing material  BIOTRICKLING FILTER Packing Material BIOTRICKLING FILTER BIOTRICKLING FILTER  BIOTRICKLING FILTER Temperature The Temperature has an important effect on odor elimination rate. Best temperature are between 28-35 C. So special consideration should be take in cold climates.  PHOTOIONIZATION Photoionization is a method of effective and reliable elimination of odors. Photoionization is mostly used for treatment of odors released by waste, wastewater (sewage) and wastewater sludge, Food processing plants. The technology of Photoionization is essentially based on the application of UV-light and a catalyst. As a physical – chemical treatment method, Photoionization is not sensitive regarding environmental conditions. Photoionization treats odor as a whole and does not focus on elimination of single chemical substances (as chemical scrubbers do).  PHOTOIONIZATION Photoionization, as a new generation in odor control provides the following important advantages: - Effective treatment of high and varying odor loads - High and guaranteed treatment efficiency - Incorporated redundancy - Extremely low maintenance and operation demand - No water, no chemicals and no nutrients required, no effluent produced - Easily expandable - Photoionization works well with high inlet temperatures and humidity’s - Reduced installation and operation costs.  PHOTOIONIZATION Only electricity is required for operation of the treatment units, but no water, no chemicals, no nutrients etc. as for other technologies. Photoionization is basically a switch ON / switch OFF technology, easy to handle, reliable and save in operation. Maintenance demand is considerably low and limited to one day of work per unit per year ! PHOTOIONIZATION