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Homepage > CMRC understandings > 【CMRC understanding】With the continuous promotion of environmental protection policies, new carbon sources usher in a good opportunity for development, and future commercial use is worth looking forward to!
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With?the?continuous?promotion?of?national?environmental?protection?policies?and?the?continuous?improvement?of?people's?environmental?awareness,?the?requirements?for?the?discharge?of?treated?sewage?are?increasingly?strict,?especially?the?discharge?of?nitrogen.?At?present,?the?common?method?used?by?many?urban?sewage?treatment?plants?or?reclaimed?water?plants?is?to?remove?nitrogen?by?adding?carbon?sources.?The?traditional?external?carbon?sources?are?mainly?methanol,?sodium?acetate,?glucose,?etc.,?but?the?traditional?carbon?sources?have?shortcomings?of?poor?safety?and?high?cost,?which?limit?their?further?development?and?application.?In?this?context,?new?carbon?sources?usher?in?a?good?opportunity?for?development.
1.?Definition?and?classification?of?carbon?sources
Carbon?sources?are?nutrients?used?to?form?carbon?sources?in?microbial?cells?and?metabolites.?The?common?classification?method?in?the?industry?is?to?divide?carbon?sources?into?single?carbon?sources?and?composite?carbon?sources.
Single?carbon?source:?a?carbon?source?containing?only?one?effective?carbon?source?component.
Composite?carbon?source:?a?carbon?source?consisting?of?two?or?more?effective?carbon?source?components,?which?must?be?compatible?with?each?other?and?free?from?chemical?reaction?and?safety?risk.
2.?Analysis?of?carbon?source?industry?chain
The?whole?industrial?chain?of?carbon?source?includes?the?whole?process?of?raw?material?collection?and?transportation,?carbon?source?processing,?transportation?and?downstream?use.
From?the?perspective?of?carbon?source?raw?material?suppliers,?different?carbon?sources?require?different?kinds?of?raw?materials?with?diversified?sources,?but?they?are?basically?purchased?and?rarely?produced?by?themselves.
From?the?perspective?of?carbon?source?production?enterprises,?due?to?the?low?threshold?of?carbon?source?production?technology?and?the?large?number?of?participating?enterprises,?they?are?basically?in?a?state?of?complete?competition.?In?addition?to?transportation?costs,?few?carbon?source?enterprises?choose?to?develop?across?regions.
From?the?perspective?of?downstream?users,?they?are?mainly?sewage?treatment?plants?(mainly?divided?into?industrial?sewage?treatment?plants,?domestic?sewage?treatment?plants,?and?municipal?sewage?treatment?plants),?some?reclaimed?water?plants?(equivalent?to?the?upgrading?of?sewage?plants,?and?the?reclaimed?water?can?be?used?for?municipal?greening,?parks?and?ponds,?etc.),?and?a?small?amount?of?garbage?leachate?from?garbage?transfer?stations.
3.?Factors?affecting?carbon?source?selection
According?to?the?CMRC?survey,?it?is?found?that?the?influent?water?quality?and?wastewater?retention?time?of?the?water?plant?will?affect?the?carbon?source?selection.?Among?them,?the?carbon?nitrogen?ratio?is?very?important?for?water?quality.?This?indicator?is?related?to?the?region,?water?plant?type,?season?and?other?factors.?If?the?carbon?nitrogen?ratio?is?greater?than?5,?the?water?plant?can?not?add?carbon?sources?throughout?the?year.?If?the?carbon?nitrogen?ratio?is?less?than?5,?different?carbon?sources?will?be?selected?according?to?the?actual?situation.?Take?the?regional?factor?as?an?example:?the?regional?factor?mainly?affects?the?domestic?sewage,?and?the?carbon?nitrogen?ratio?in?the?north?will?be?lower?than?that?in?the?south,?mainly?because?of?different?living?habits.?The?northern?people?are?used?to?drinking?high?protein?and?fatty?foods,?so?the?nitrogen?content?in?the?domestic?sewage?is?relatively?high,?leading?to?low?carbon?and?nitrogen.
4.?Carbon?source?selection
At?present,?the?most?important?indicator?for?measuring?various?types?of?carbon?sources?in?the?market?is?COD?equivalent?(chemical?oxygen?demand).?When?treating?the?same?amount?of?sewage,?the?higher?the?COD?equivalent?of?carbon?sources,?the?less?the?total?amount?needed?to?be?added.?Other?indicators?include?denitrification?rate,?reaction?stability?and?sludge?yield.
Historically,?single?carbon?source?is?the?product?with?the?longest?application,?mainly?including?sodium?acetate,?glucose?and?methanol,?among?which?glucose?and?methanol?are?relatively?less?used,?especially?methanol.
??Sodium?acetate:?from?the?perspective?of?economy,?the?market?price?of?sodium?acetate?is?low,?and?the?price?is?more?expensive?under?the?same?COD?equivalent;?From?the?use?effect,?sodium?acetate?has?the?fastest?reaction?rate,?good?stability?and?nitrogen?removal?effect,?and?the?best?comprehensive?market?performance.
??Glucose:?from?the?perspective?of?economy,?the?price?of?glucose?in?the?market?is?expensive?and?relatively?cheap?under?the?same?COD?equivalent;?From?the?perspective?of?use?effect,?glucose?sludge?has?a?large?output,?high?sludge?treatment?cost?and?few?practical?applications?in?the?market.
??Methanol:?from?the?perspective?of?economy,?the?market?price?of?methanol?is?on?the?high?side,?and?the?price?is?cheap?under?the?same?COD?equivalent,?so?the?economy?is?better;?From?the?perspective?of?use?effect,?methanol?is?single?in?composition,?flammable?and?explosive,?with?high?safety?risks?and?few?practical?applications.
In?general,?there?is?no?standard?product?in?the?composite?carbon?source?market,?which?is?formulated?according?to?customer?needs.?From?an?economic?point?of?view,?the?composite?carbon?source?makes?full?use?of?the?advantages?of?the?main?components,?including?the?high?COD?of?small?molecule?alcohols,?the?high?reaction?rate?of?sodium?acetate,?and?the?high?microbial?absorption?of?sugar.?The?result?is?that?the?concentration?of?organic?matter?is?relatively?high,?the?COD?equivalent?is?relatively?large,?and?the?overall?measurement?results?in?a?significant?reduction?in?the?dosage,?and?also?reduces?the?cost?of?transportation,?unloading,?and?storage?tank?facilities.?The?comprehensive?cost?is?low,?and?the?cost?performance?is?high.?From?the?perspective?of?use?effect,?the?nitrogen?removal?effect?is?good,?and?the?reaction?rate?is?in?the?middle.?Although?the?stability?is?weaker?than?that?of?a?single?carbon?source?(it?does?not?affect?the?use,?and?only?needs?to?be?tested?before?each?batch?is?used),?the?composite?carbon?source?can?be?used?by?denitrifying?bacteria?in?biochemical?sludge,?not?by?microorganisms?such?as?filamentous?bacteria?that?cause?excessive?sludge?growth,?and?the?sludge?production?is?relatively?small.
5.?New?carbon?source
The?new?carbon?sources?can?be?divided?into?solid?carbon?sources?and?liquid?carbon?sources?according?to?the?physical?state,?of?which?the?solid?carbon?sources?include?natural?cellulose?carbon?sources,?artificial?synthesis?solid?carbon?sources,?etc;?Liquid?carbon?sources?include?high?concentration?industrial?organic?wastewater,?sludge?hydrolysate,?kitchen?waste?hydrolysate,?fruit?and?vegetable?waste?anaerobic?fermentation?liquid,?etc.
Under?the?influence?of?the?new?sewage?treatment?concept,?the?new?carbon?source?with?high?efficiency,?environmental?protection?and?low?cost?has?become?the?current?research?focus?of?universities?and?manufacturers.?The?new?solid?carbon?source?is?difficult?to?control?and?has?high?cost.?The?new?liquid?carbon?source?represented?by?high?concentration?industrial?organic?wastewater,?sludge?hydrolysate,?food?waste?hydrolysate,?and?fruit?and?vegetable?waste?anaerobic?fermentation?liquid?can?not?only?remove?nitrogen?efficiently,?but?also?conform?to?the?concept?of?waste?resource?reuse.?However,?there?are?still?some?problems?that?restrict?its?wide?commercial?use,?Therefore,?the?research?focus?of?new?carbon?sources?in?the?future?will?be?more?on?how?to?widely?commercialize.
summary
There?are?more?or?less?problems?with?the?traditional?carbon?sources?currently?used.?With?the?promotion?of?environmental?protection?policies,?sewage?discharge?requirements?are?increasingly?strict;?With?the?impact?of?the?epidemic?and?the?economic?downturn,?manufacturers?have?to?control?costs,?so?there?is?an?urgent?need?to?use?a?new?type?of?carbon?source?that?is?more?environmentally?friendly?and?economical?at?present?and?in?the?future.?Although?most?of?the?existing?new?carbon?sources?are?still?in?the?laboratory?stage,?and?there?are?still?various?problems?in?practical?application,?they?have?the?advantages?of?environmental?protection,?low?cost,?and?research?has?been?making?progress.?It?is?worth?looking?forward?to?when?they?can?be?large-scale?commercial?in?the?future.
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