The O · PARK1 has a design capacity of 200 tonnes per day. It adopts anaerobic digestion and composting technologies to recycle source separated food waste into biogas and compost. The biogas will be used to generate electricity and apart from the internal use within O · PARK1, about 14 million kWh of surplus electricity, which is equivalent to the power consumption by some 3,000 households, can be exported each year.
Food waste collection vehicle passes through the weighbridge for recording the weight of food waste received before discharging into the bunker at the tipping bay. The enclosed tipping bays are equipped with double doors and an advanced deodorisation system to prevent odour from escaping to surrounding areas.
A grab crane is used to transfer food waste to the crusher, which tears up the packaging materials, smashes and turns the food waste into suspension. Food waste suspension is then transferred to the Trommel Sieve Drum to remove the over-size impurities of about 16mm in size or greater, such as plastic bag fragments. Afterwards, the suspension passes through the Sand Grit Trap where heavy impurities such as glass, stones and sand are removed. Metals are also separated from the food waste for recycling.
The processed suspension firstly enters the buffer tank, followed by three digesters, each of approximately 4,300m³ in volume. The digesters operate at about 35°C under anaerobic condition, where mesophilic microorganisms convert the suspension into biogas in around 23 days.
Biogas collected is diverted to the desulphurisation column for biological oxidation of Hydrogen Sulphide (H2S), to avoid corrosion of the downstream equipment. The column operates at a temperature of about 30˚C, which converts H2S into sulphate for removing 95% of the H2S. Cleaned biogas is then stored in a 1,500m³ Double Membrane Gasholder housed inside a steel tank shell. Pressure relief device is also provided to ensure the safe operation of the system.
The Combined Heat and Power generation units combust treated biogas to generate electricity to self-sustain the operation of the facility and export surplus electricity to the power grid, which is sufficient for the power consumption of approximately 3,000 households. Heat is recovered from the system to satisfy the heating demand within the facility.
Digestate from the digester is dewatered by the centrifuge to achieve a solid content of about 25%, and then mixed with bulking agent before being transferred to the composting tunnels for stabilisation. The mixture is placed inside the composting tunnel for about 20 days to facilitate degradation of remaining organic matters. Air distribution system and irrigation system are installed in each tunnel for supplying air to the composting process and adjusting the compost moisture content. Heated air is delivered to the tunnel for maintaining the operating temperature at about 55˚C. The mature compost can be used for landscaping and agriculture applications.
All facilities within O · PARK1 are confined and maintained under negative pressure to avoid odour dispersion. The odorous gases within the facilities are extracted to the deodorisation system. The system comprises of Venturi Scrubber, Wet Scrubber, 2-stage Chemical Scrubber, and Activated Carbon Filter to remove dust particles and odorous chemicals (mainly H2S and NH3). The system can achieve a minimum of 95% NH3 and 99% H2S removal efficiencies. The performance of the CAPCS is continuously monitored to ensure the compliance with statutory requirements.
The wastewater treatment plant is divided into three stages: Pre-treatment, Ammonia Stripping Plant (ASP) and the biological treatment. The pre-treatment involves flocculation and sedimentation to remove a majority of Total Suspended Solids and Phosphorus. Wastewater is then pumped to the ASP for ammonia removal. The ASP column is filled with polypropylene packing to facilitate the ammonia transfer between gas and liquid phases. Sequencing Batch Reactor with anoxic and aerobic stages is adopted as the biological treatment for the removal of the organic pollutants and nitrogen.
A portion of treated effluent is reused on site. The remaining volume is discharged to sewage treatment works for further treatment. Discharge of effluent is closely monitored to ensure its full compliance with statutory requirements.
If you are interested in delivering food waste to O · PARK1, please submit “Expression of Interest” Proforma to us. For any questions or comments about food waste source separation, collection and delivery, or updates of your registered details, please contact us by:
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Environmental Protection Department, Organic Waste Infrastructure Group, Room 1501 - 1504, 15th floor Chinachem Exchange Square, 1 Hoi Wan Street, Quarry Bay, Hong Kong |
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+852 2285 7604 |
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+852 3528 0492 |
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Organic Resources Recovery Centre Phase 1, 5 Sham Fung Road, Siu Ho Wan, North Lantau. |
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+852 2143 7510 |
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booking@opark.hk |
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+852 2264 6661 |
