There are several ongoing tasks which completed 50%. Among the task are collecting used tyres and plastic bags.
On 19 July 2009, 4 tyres were collected from ART Car Auto Service and some plastic bags were accumulated from “Greencamp” organized by ICE uniten student chapter and home usage.
In fact, several parties were informed about the ongoing project which consists of DOE, Business Council for Sustainable Development Malaysia, Global Environment Centre, and journalist from TV3. They were invited to give comment on the ongoing research while assist in future funding. The contact method consists of sending text messages and email on 20 July 2009.
On 27th August 2009, there was an appointed with Mr. Fazli who assist in trimming the tyre. However there was no machine which could be used in trimming the tyres. Hence the only method was trimming it with grinder manually.
- Instability during both start-up and operation of the anaerobic degradation can be problematic due to the low specific growth rate of methanogenic microorganisms.[1]
- Under conditions of unstable operation, intermediate such as VFA and alcohols accumulate at different rates depending on the cause of the instability.[2]
- Most common causes of imbalance are hydraulic or organic overloading the presence of toxins and changes in the substrate concentration. Several parameters are used as indicators of stress, such as variations in gas production rate, gas consumption, pH, PA and VFA concentration.[3]
- Clogging of reactor and decay of material after a year were encountered during the study.[4]
- The reason anaerobic contactor is chosen is due to the production of digested sludge which is mainly used as fertilizer for crop production since nutrients in raw material remain in mineralized sludge as accessible compounds. [5]
- According to the journal, proper design and scale-up of anaerobic reactors requires knowledge regarding correlations between reactor configuration and process efficiency to set the limit for the biochemical operating parameters.
There are 2 types of Anaerobic Digestion process:
- Ø Mesophilic Digestion: Digester heated to 30-35℃ and feedstock remains in digester typically for 15-30 days. This system is more robust and tolerant but gas production is less while larger digestion tanks required and sanitization.
- Ø Termophilic Digestion: Digester heated to 55℃ and residence time is typically 12-14 days. It offer higher methane production, faster throughput, better pathogen and virus “kill” but require expensive technology as greater energy and higher degree of operation and monitoring. During this process 30-60% of the digestible solids are converted into biogas.
The reason anaerobic packed –bed reactor selected for this research is due to the advantages which consist of:
- The packing medium in the packed-bed reactor and the granular sludge in the UASB reactor serve as a filter preventing bacterial washout and also providing a larger surface area for faster biofilm development and improved methanogenesis.[6]
ü Specific surface area porosity, surface roughness, pore size and orientation of the packing material were found to play an important role in anaerobic reactor performance.[7][8] - Many carrier materials have been investigated regarding their suitability as support for biofilm including cheap, readily available materials like sand, clay, glass, quatz and number of plastics.[9]
- Pore size was one of the most important parameter for microbiological and engineering requirements in higher efficiency beds.[10]
- Microorganisms exist not only in the spaces within the carriers but also attached to its surface. Hence, a higher density microbial population is retained within the reactor. Thus allowing a biomass retention time longer than the HRT. [11]
According to the author, the employment of the up-flow type digester as an economical and effective treatment for significance in reducing the organic load of total raw material.
While on the other hand the journal known as “Treatment of screened dairy manure by upflow anaerobic fixed bed reactors packed with waste tyre rubber and a combination of waste tyre rubber and zeolite: Effect of the hydraulic retention time” by Oscar Umana, Svetlana Nikolaeva, Enrique Sanchez, Rafael Broja, Francisco Raposo support the research feasibility.
A wide variety of natural materials such as smooth quartzite, pebbles, shells, granite stones, cinder, volcanic stones, zeolite, wooden blocks, brick ballast and synthetic materials like polyvinyl-chloride sheets, needle-punched polyster, glass, rasching rings, tyre rubber and other materials have been used for the attachment and growth of anaerobic biomass. [12-20] Waste tyre rubber has also been used as support media in the treatment of piggery waste, distillery waste and sewage with considerable removal efficiencies, showing the suitability of the material as a support medium in anaerobic fixed bed reactors. [21]
The author also state that the research should look into the effect of HRT on the process stability organic matter (COD,BOD5,TS and VS) removal efficiencies and methane yield.
