Start Up, Shut Down

Start Up • •

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Steam clean through maintenance hatch to ensure sterility Digester flled with bioethanol plant euent while agitation starts when operating level reached Stabilised to mesophilic temperature (35 oC) Headspace purged with itrogen gas ! also biogas piping purged ("or sa"ety and ensure completely anaerobic conditions) Digester seeded with biologically activated sludge (procured "rom similar plant) ! #roduces population o" bacteria re$uired "or %D& 'olume o" seed solid is approimately &5* o" total volume& (Can reduce the start+up time to two wee,s or less compared to the - days o" no seeding) ! Saves on additional chemicals to control pH .low o" organic slurry starts at very slow rate and incrementally increased over ensuring digester conditions remain within the ranges provided/ o Temperature Temperature between 34.5 and 35.5 C, with 35 C target value. Ratio of volatile acids/alkalinit less than !.35 o o  p" between #.5 and $.!, with target value of %.& o Ratio of T' feed/T' in digester between !.!5 to !.& o Ratio of (' feed/(' in digester between !.!3 to !.& )igester gas methane concentration higher than 55* b volume concentration o +ntil full flow is increased, the digester effluent can be reccled

0t can ta,e up to 3-days to achieve "ull operation o" the digester due to the slow growth o" the anaerobic1 methane "orming bacteria&

2& Hatigeirgiou 4 & 6wsene, (7--8) ! Startup o" %naerobic 2esophilic Digesters1 9ater :nvironment .oundation #&C& Suryawanshi 4 %&& Chaudhari (7-;3) ! 6perating #rocedures o" :ournal o" %nimal1 'eterinary and .ishery Sciences1 'ol ;

Maintenance 9hen maintenance may be re$uire Hydraulic washout1 temperature loss1 mechanical repairs1 organic overload or toic loading/ %ll piping can be isolated "or cleaning itrogen purge to remove any ?ammable biogas be"ore access to digester Suitable plans to replace any "ailed e$uipment e&g& agitator 2ultiple temperature sensors to ensure mesophilic conditions& 'ariable ?ow on heating system to help maintain system temperature1 alter ?ow until temperature is e$ualised& Slow miing to reduce heat loss through the thin fed dome roo"& 0" hydraulic washout occurs through accidental over pumping ! recycle slurry "rom the digester and reduce the "eed rate&

6rganic or toic over loading ! increase in?uent to dilute content

Cleaning 2aimum "re$uency is once every three years& Cleaning re$uired i" ! @rease or grit accumulation occurs1 miing e
Shut Down • • • •

 urn o "eed and agitation Drain digester (i" going to be restarted ! leave ;5* "ull) #urge system with nitrogen Eeave to e$ualise ;+7 days and re+purge then open to environment