Eng. Piero Rusconi Clerici

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New integrated solution for disposal of household
food waste to enable decentralized production of
energy in existing infrastructures
Eng. Piero Rusconi Clerici Brussels 12th February
2009
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INTRODUCTION
First of all I would like to thank the
Organization and the people attending the
workshop. Its an honor to have the possibility
to tell you the job done by the ReWISe Group
made-up of 6 Companies from three different
Countries in a very effective mix of competences

• two big industrial Groups

• two Universities (plus one in a collateral
  position)

• one big engineering company

• one innovative and highly focused small company

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ReWISe synthetic description

• ReWISe has been supported by European Agency for
  Competitiveness and Innovation (EACI) in the
  frame of an Intelligent Energy Europe (IEE) call,
  with the scope to understand and possibly to
  overcome the problems limiting the intensive use
  of the appliances called Food Waste Disposers
  (FWDs), capable to grind in a high selective way
  the Kitchen Food Waste (KFW) in view of producing
  energy from renewable sources, using existing
  infrastructures i.e. sewerage and Waste Water
  Treatment Plant (WWTP) fitted with an anaerobic
  digester.

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The conservative/negative attitude toward the FWDs

• The FWDs are appliances quite old, being
  invented in the far 1927 in USA. In this Country
  they had a booming development across the Sixties
  and the Seventies up to the Eighties. FWDs were
  adopted by a lot of real estate developers for
  their friendly use in disposing the KFW.
• Clearly this appealing feature is not
  sufficient to let sell nowadays the machines in
  Europe, in view of the strong concern on the
  environmental respects. In other words its
  difficult to sell the FWD in an uncontrolled
  market, because at least they require the
  presence of a sewerage and a WWTP well
  performing.
• Besides this right worry it could be naïve to
  forget that FWDs operate an important revolution
  in the way of collecting the KFW because they
  transform a solid waste in a waste water and by
  consequence they can transfer a huge amount of
  work of the Municipal Solid Waste (MSW) from the
  existing solid stream to the liquid one.
• Finally we have also to consider that, in most
  of the cases, the managers leading the
  environmental companies are cautious, sometime
  reluctant, to change because of understandable
  reasons.

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The ReWISe answers
Starting from the aforementioned points the
ReWISe partners have approached step by step the
new managerial model under the following respects

• Economical respects
• Legal respects
• Technical respects
• Environmental respects

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Economical respect

• This respect represents in our opinion an
  important barrier to the FWDs spreading.
  Therefore the FWDs used in ReWISe have a peculiar
  improvement they are equipped with a innovative
  quantifying device that, through a complex
  statistical algorithm, can give an approximate
  (/- 8) value of the organic load routed to the
  Waste Water System (WWS) by each household.
• This fact, for the first time, allows to
  overcome two important issues to keep informed
  the Authorities on the amount of waste diverted
  from the solid stream to the liquid one, and to
  create the conditions through which the Companies
  treating the KFW can manage the correlated costs.
• In effect the FWDs revolution create a lack of
  balance in economics the Water Company (WC)
  incurs in a rise of costs not always compensated
  by the incomes generated by the sale of green
  energy (as well see later on), while the
  Municipal Solid Waste Company (MSWC) should loose
  part of its job.

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Economical respect

• Its clear that machines capable to give the
  amount of waste processed can allow, from one
  side the WC to apply for a tariff for this
  service and/or to MSWC to keep the work, asking
  the WC to employ its infrastructure and paying
  for that an agreed fare.
• We can say that in this way its accomplished
  what is called Waste Water-Waste Integrated
  Cycle. For the WC its important to notice that
  this new service is not included in the existing
  fares, but its a new service that the users have
  to pay saving probably part of the waste taxes.
• It s available an on line tool on the ReWise
  website (www.re-wise.org) to evaluate
• the Municipality costs and the family costs both
  for the separate system collection and the Rewise
  model adoption
• the costs for the investors and the gains
  associated to the implementation of the Rewise
  model

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Legal respect

• This is another important issue because the bans
  or the limits to the FWDs use are different
  throughout Europe.
• First of all we can say that today a ban is
  contrary to the general rules of the
  international trade agreements (like WTO) and the
  Authorities, banning the use of the FWDs, can
  face a sentence of abuse of dominant position.
• I dont want to enter in a legal discussion but
  I can say that the case is under evaluation at
  the Antitrust Commission in Italy and we presume
  that they will confirm this position.
• The risk of abuse of dominant position
  sentence of course doesnt mean that the
  Authorities are invited to deregulate the FWDs
  sale, but only that the ban is illegal and agreed
  limits on the number of FWDs are to be
  pinpointed.
• The rise of FWDs installed will depend on the
  business opportunity perceived by the WCs, on the
  reduction of costs of this model (and fares for
  the household) and on the environmental benefits
  depending on biogas produced and Global Warming
  Potential (GWP) reductions.

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Technical respects

• The FWDs are machines that, despite the fact
  they were designed to simplify the life, have
  their grinding apparatus capable to select the
  waste dropped in.

• First of all they shred the material
  projecting it against a grinding ring. Only
  fragile materials are affected, while lighter
  wastes (plastic) remain in the centre of the
  grinding chamber because of the their reduced
  centrifugal forces (lower mass)

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Technical respects

• Regarding the sewerage impact we can divide it
  in two principal themes sedimentation and FOG
  (Fat-Oil-Grease).
• Sedimentation depends of course on the local
  diet, according to an intensive study carried out
  in Italy 13 of the waste sediment, while 87
  reach the WWTP (Ingegneria Ambiente 2002).
• Fog phenomenon is a nightmare for the WC and we
  know that an intensive study is undergoing in UK.
  It will terminate by the end of 2009. Actually it
  can be said that the constituents of fog that are
  into the food waste tend to coalesce to the
  ground particles once treated by a FWD and not to
  adhere to the drain surfaces (Tim Evans and De
  Konig).
• In any case a ReWISe Model can be implemented
  trough a step-by-step growth. This is a very
  important issue for a community adopting the
  model because all the impacts or actions needed
  to be implemented can be controlled installing
  the FWDs in an identified area and then in the
  next one.
• This is possible in view of approaching the FWDs
  as tools for the waste collection and not as
  simple household appliances.

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Technical respects

• Once the ground food waste arrives to WWTP its
  necessary to intercept it into the primary
  clarifier where sediments and floating materials
  are collected and routed to the anaerobic
  digester.
• The suspended organic load (a ready
  biodegradable COD), increasing the carbon
  quantity, can be usefully used at the biological
  treatment section of the plant for nitrogen and
  phosphorus removal (D-N and BNR treatments).
• The wastes routed to the Anaerobic Digestion
  (AD) represent the most attracting opportunity.
  Today it is possible to exploit existing
  infrastructures treating only the secondary
  sludge.
• The co-digestion sludge and food waste represent
  an extraordinary increase to the biogas
  production (realistic figure, including any
  possible loss in the sewerage network, indicate
  120m3/ton_waste) and to the actual performances
  of the digester.
• The increased biogas and the correlated energy
  achievable 720 kWh/ton_waste can be totally
  exploited to the plant thanks to the electrical
  energy sold to the national grid, while the heat
  generated can be used in part to keep the
  anaerobic process more efficient or to bring it
  to the thermophilic stage instead of the
  mesophilic one, in part, if requested, to dry-up
  the sludge.

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Technical respects

• With respect to IEE priorities, the proposed
  action would contribute to set up the basis for
  ultimately reaching the implementation of the
  proposed model, which would lead to an increase
  in biogas production for anaerobic co-digestion
  of household organic food waste at WWTPs equipped
  with primary clarifier, of up to 77 for a
  penetration rate of domestic food waste disposers
  of 100. The following graph gives an overview of
  the increase in biogas production at the WWTP,
  for different rates of penetration of domestic
  food waste disposers and for different sizes of
  the WWTP.

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Technical respects

• The digestate obtained at the end of the
  anaerobic process is very interesting because
  is free of physical contaminants conserve
  nitrogen from feedstock whereas composting
  volatilizes it as ammonia gas.. (and thus)the
  proportion of nitrogen that is plant-available is
  greater in digestate than it is in compost (Tim
  Evans, 2007).
• Considering the viscous aspect of the digestate
  it can be probably used in a quite new
  techno-agricultural application called
  hydro-seeding used on the reinforced ground
  structures or green walls fitted along the new
  high speed railway in Italy.

• This application present less impact because its
  an agricultural use separated from the alimentary
  cycle.

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Environmental respects

• Its not easy to calculate the environmental
  advantages of one technology even because there
  is the risk to forget something or to over
  evaluate the contribution due to the
  unpredictable behavior of the each situation.
  Here below we tried to point out some evident
  savings.
• Thanks to ReWISe its possible to reduce the
  amount of CO2 generated by the vehicles
  collecting the KFW. The carbon footprint
  according the information found (Tim Evans 2007)
  is 0,25Kg CO2/ton/km that means in a year time
  1000 FWDs can save 52 kg of CO2 each km non
  traveled to the disposing site.
• Under the digestate point of view the Tim Evans
  study reports the following figures Using
  digestate has the same benefits as using compost
  and conserves more of the nitrogen fertilizer
  value .(having) 22kg short-cycle CO2 sequestered
  /t waste and 36 kg CO2e GWP avoided/t waste for
  the fertilizer replacement value.

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Environmental respects

• Finally we can underline that the most fine
  particles of the KFW treated by the FWDs, not
  intercepted in the primary clarifier, can
  contribute to increase the ratio C/N at the D-N
  and BNR treatments, being ready biodegradable COD
  (rbCOD).
• The test conducted in central Italy (Battistoni
  et al. 2006) has shown clearly this behaviour.
• Last but not least in modern environmental
  policy the people participation is considered
  central.
• Sustainable Environmental Communities can play
  a great role to develop Re WISe thanks to fact
  that the ReWISe FWDs are capable to give to
  their inhabitants the perception of how much they
  contribute to the production of green energy
  (even if other environmental parameters can be
  used such as GWP reduction) using these
  intelligent households.

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Field tests and SECs

• We clearly understand for the aforementioned
  reasons, that ReWISe should be analyzed with
  high attention and caution by the decision
  makers, nevertheless we believe that its worth
  to remember, as already said, the story of
  diffusion of such technology in North America,
  where the growth of the FWD market shown an
  important trend during the Sixties and Seventies.
• At that time an important migration flow (mostly
  young and single) took place from the North to
  the South States, with a correlated changes in
  life style, including the time dedicated to the
  wastes collection. A lot of new buildings were
  equipped with FWDs.
• Today most of 110 millions of disposers are not
  presumably equally distributed all over the
  Country, most probably they are concentrated in
  specific areas, even these statistics are hard to
  be found.

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Field tests and SECs

• If we accept this analysis, we can say that
  intensive use of FWDs is not new, what is new is
  the control of the new stream, it is mandatory to
  fairly charge the appropriate costs and revenues,
  its strategic to produce green energy
  exploiting existing infrastructures.
• In Europe FWDs have been tested under this
  environmental and managerial respect in Sweden,
  where a number of cities promoted the
  installation of FWDs through tax incentives,
  Norway, in UK (e.g. up to 80 cashback for
  residents of Herefordshire and Worcestershire for
  buying and installing a FWD, 2007), in Italy, in
  Ireland.
• Among SECs the ones located in the islands are
  among the most promising, mainly for the lack of
  space typical of these areas and their economy
  based on the tourism.
• For that reason we welcome Santa Cruz de
  Tenerife as the first SEC evaluating ReWISe
  model.

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Opportunities

• We would appreciate the developers of new
  technologies involving the biogas production or
  the managers of the WWTP to let us know their
  interest in the implementation of the Rewise
  model
• We remain at your disposal for any further your
  request
• Our contacts are
• www. Re-wise.org (see the webpage on the
  background), you can register and be part of the
  Rewise virtual community
• piero.rusconi_at_ecofast.eu

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THANKS FOR YOUR ATTENTION