B3 - Test run

B3 - Test run
Batch digestion tests with controlled input
Calibration of COWS subsystem
Incremental optimisation of the full process
Test of operational limits
M - Validation of full scale COWS process
D5 - COWS performance report

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Description and methods employed (what, how, where and when)

The main purpose of this action is to get:

• optimal processing through the COWS pre-treatment prototype subsystem;
• optimal overall performance of the plant

In order to achieve this goal adjustment and balancing of process parameters are to be done.

Adjustments of COWS pre-treatment prototype subsystem depend on the technology adopted; they are anyway similar in both cases of screw-press and piston-press (the most probable technologies). It would be different for hydro-mechanical separation.

We take as reference the extrusion process.

In order to evalute the performance of pre-treatment unit (COWS prototype) the presence of contaminants will be consider the principal factor. Tests include both chemical, physical, and ingredient analyses. The following contaminants/contrary materials are measured (relative to the organic fraction)

• Putrescible
• Plastics
• Metals
• Glass
• Textiles
• Wood
• Paper
• Inerts

Adjustments should consider the performance of each stage and the effects on subsequent steps. Characterization will be made at each step on residuals and in-flow materials, starting from influent OFMSW characterisation. Following steps are:

• after pre-treatment, out of the press/screw system;
• mixer content (floating, pulp precipitate, pulp outflow);
• digester (fermentation values and digestate)
• surnatants

Main process data monitored are:

• Chemical composition of OFMSW and WAS influent (average monthly)
  • TS, g/kg
  • TVS, %TS
  • TCOD, mgO2/l
  • TKN, mgN/l
  • Ptot, mgP/kgTS
  • Alkalinity, mgCaCO3/l
  • pH
• Operational conditions in the reactor
  • Feed caracteristics
    • Material
    • TS feed, %
    • TVS feed, %TS
  • Operational conditions
    • OLR (kgTVS/m3reactor day)
    • HRT (days)
    • Digester temperature, °C
  • Process parameters
    • pH
    • Alkalinity (@pH 6), gCaCO3/l
    • Alkalinity (@pH 4), gCaCO3/l
    • Volatile fatty acids, mgCOD/l
    • TS reactor, %
    • TVS reactor, %TS
  • Yields
    • GP, m3biogas/twaste
    • GPR, m3biogas/m3reactor day
    • SGP, m3CH4/kgTVSfeed
    • SGPsludge, m3CH4/kgTVSfeed
    • SGPofmsw, m3CH4/kgTVSfeed
    • CH4, %
    • TVS removal, %

Foreseen adjustment of the prototype considering the case of extruder technology can be done acting mainly on the following:

• extruder piston pressure (or cochlea speed);
• distance between piston (or cochlea) and the head of extrusion chamber;
• screen patterns (hole diameter and distribution).

While pressure regulation and feeding can be done continuously, changes in distance between piston and cylinder and subtitution of screens must be off-line, with mechanical operations.

Adjustments on mixer are about rotation speed and the height of suction pump.

Ajustments on digester are about

Constraints and assumptions

Indicate what may prevent you from implementing the action as planned and what will be done to address this risk. Please ensure that these constraints and assumptions are in line with those indicated on Form B5.

Beneficiary responsible for implementation

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Expected results

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Indicators of progress

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Notes and References

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