Water and Effluent Treatment Magazine
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16 WET NEWS JULY 2017 An AD plant's longevity can be adversely a ected by a number of things, but toxic gas can impact performance if left untreated. Top tips on toxic gas treatment to prolong AD plant lifespan INSIGHT Sewage & sludge treatment THE CONCEPT The Sulfurex Selection Work Expert Tool correlates gas flow rate and inlet H2S concentration † gures to identify the best suited technology A tailor-made business case is generated by con¬sidering site-speci† c conditions NEED TO KNOW 1 Biogas produced through the decomposition of organic matter contains hydrogen sulphide 2 Removing H2S can increase uptime by 50% to 30,000 hours 3 The most damaging side e ect of H2S is its ability to corrode essential plant equipment 4 For high concentrations of H2S, chemical scrubbers are usually recommended, while for biogas upgrading, activated carbon † lters are typically used as a pre-treatment THE VERDICT "The SSweet allows an AD plant operator to select the most suitable technology for their project from both a tech¬nical and † nancial standpoint, preserving the life of their plant – and their pro† t margins – for years to come" DMT D eveloping an anaerobic digestion (AD) plant does not come cheap. Costs range from £100,000 up to as much as £24M. When calculating their costings and potential return on investment (ROI), developers o- en plan for a plant lifespan of 20 years, so it is essential that plants are well maintained to avoid unexpected expense. This is particularly important as there are a number of things which can adversely a… ect a plant's longevity, such as large deposits of grit, the absence of a pressure relief valve, foaming and process instability, for example. In addition, there is ‡ DMT's Sulfurex CR desulphurisation technology at a Manchester AD plan an invisible threat to AD plants which, if le- untreated, can seriously impact performance, proˆ t and plant lifespan – sulphide. Bugs Biogas produced through the decomposition of organic matter contains hydrogen sulphide (H2S), a colourless, toxic gas which is one of the main inhibitors of micro- organic growth; if the bugs can't get to work within the digester to break down the organic matter, then the volume of biogas produced per tonne of feedstock will be dramatically reduced, a… ecting an AD AD operators use the Sulfurex Selection Work Expert Tool (SSweet) to determine the best desulphurisation technology Desulphurisation sweet spot selection Gas Flow Rate (Nm 3 /h) 3.000 ppmv Bio-chemical or Biological Biological Chemical ACFs Inlet H2S concentration (ppmv) Bio-chemical Biological Bio-chemical or Biological Bio-chemical or Biological Biological Chemical Biological 3.000 ppmv Bio-chemical or Biological Bio-chemical or Biological Bio-chemical or Biological