Anaerobic digestion (AD) is a treatment that composts organic waste in the absence of free oxygen, producing a biogas that can be used to generate energy, taking into account several parameters that affect the anaerobic digestion process i.e. pH, Temperature, Chemical Oxygen Demand and Total Solid.
The main objective of this project is to produce biogas from organic waste by anaerobic digestion, applying this project has importance such as using a clean, economical, and attractive method for waste disposal instead of different contaminated methods like land fill or incineration.
This project consists of five experiments; the first one was to study the pH variation during biogas production with food seeding, the second was to select the suitable buffer type from (Na2CO3 as powder, NaHCO3 as powder , and a buffer solution of Na2CO3 and NaHCO3) that stabilize the pH within the range (6.8 -7.2), the third was to study the effect of sodium carbonate buffer amount on the pH value for anaerobic digestion process, the fourth was to study the effect of sodium carbonate buffer on the pH stability of anaerobic digestion process, and the final experiment was to study the effect of sodium carbonate buffer on the amount of biogas produced.
For the purpose of executing experiments Food waste (FW) was collected and categorized for its potential to be used as feed stock for AD process.The FW was pretreated by grinding then mixing with seeding and finally diluted with water at different ratios, meanwhile seeding was prepared too, then the bioreactors were incubated in a water bath at 35°C as a mesophilic conditions.
Sodium carbonate buffer was the best buffer type which increased the biogas production and maintained pH stability, and the amount needed to achieve that was 249g for 10L working volume.
Seeding affects the initial pH value; comparing cow manure seeding with FW seeding it was found that cow manure increased the initial pH.
Destruction of total solid for buffer system was from 11.6% to 7.4% which was better and more stable than blank which had unstable values. Biodegradability of FW could be characterized by decreasing of COD value from 11000 to 9900 (mg/L) for blank while the buffer decreased from 16500 to 10800 mg /L; the COD removal for buffer was better than blank with a percentage of 34.5%.