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Carrigrenan Wwtp

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CE 4010: Water

and Wastewater
Treatment –
Report on
Carrigrenan
WWTP.
Due Date: 6th January 2012

Name:
Student No:
Lecturer:

Denis O’Sullivan
108348006
Prof. Gerard Kiely

University College Cork
Coláiste na hOllscoile Corcaigh

Department of Civil and Environmental
Engineering.

Introduction

near Little Island. Construction of the plant began in 1998 and concluded in 2003. Therefore. Owned by Cork city council. Since 2004. This plant is the final component of the Cork main drainage scheme which cost approximately €340m. The annual operational cost of this plant is approximately €6m. There is capacity for a further 2. Cork city now fully complies with the EU Wastewater Treatment Directive of 1991. it is expected to be able to cater for a Population Equivalent of 413. Following the construction of this plant. state of the art plant. The plant itself cost approximately €89m. the maximum flow to the inlet is 4. This is directed to the storm tanks. The targets for the plant as set out by this EU directive and the average results of 2010 are as follows: Target Average Results 2010 COD 125 mg/l 88 mg/l SS 35 mg/l BOD 125 mg/l 16 mg/l 13 mg/l Examining these results.Denis O’Sullivan.1 m3/s of influent to full treatment.08 m3/s of storm influent. Page | 1 . The plant is a fully automated. approximately 47% is domestic while 53% is industrial. Standards The plant includes both primary and secondary treatment in order to effectively treat the sewage to the EU Wastewater Treatment Directive mentioned above. it was designed and built by EPS Group and is operated by Northumbrian Water International on a 20 year contract. there is opportunity to extend the plant in the future to provide additional treatment if the need arises. It is situated on a 42 acre site in Carrigrenan.18 m3/s. 108348006 CE 4010: Water and Wastewater Carrigrenan Waste Water Treatment plant is the treatment plant which is responsible for treating most of the waste and storm water from Cork city.000. it is apparent that the plant is performing well. As a result of the fact that the plant is designed on a modular basis. surpassing the required standards. It can treat sewage from an estimated Population Equivalent of 324. Of this. the plant has treated approximately 256 million m 3 of raw sewage. By 2020.000. Capacity The plant is designed to handle 2.

Always Full .3 Modes 1.Water at top is clear and is decanted off.System operates mostly in Wet weather Mode.4 No. Speeds up if one basin is under maintenance.Length = 55m .First: Till/Aerate . Anaerobic Sludge Digestion . .8 No. Maintenance: Similar to wet Weather.Breadth = 28m .4 m Storm tanks .Depth = 6.Sludge from middle of SBR is diverted to head of SBR .Biogas produced Page | 2 .Sludge is removed in the last 10 minutes of the decant cycle and sent to the sludge dewatering station.Selector zones aerate at a different rate to the main body . .Covered: .Denis O’Sullivan. Dry Weather: Standard 3.Air is pumped in to ensure that aerobic digestion occurs and not anaerobic digestion which produces septicity (poor odours) Primary Settlement .Uncovered . . 108348006 CE 4010: Water and Wastewater Treatment Treatment Process       Screening and Grit Removal .Next: Bugs settle to bottom of basin . This is pumped into the final effluent.Volume = 3850 m3 .Rarely Full .Screening and Grit Removal for the rest of the city (90%) is carried out in Mahon Pre-aeration for septicity control .Depth = 6.Volume = 3850 m3 .For Little Island only (Approximately 10 % of influent) .2 No. Wet Weather: Fills and Empties faster 2. .Speeds up process . . .Working Volume = 8500 m3 .Depth = 6m .Decides what kind of bugs are required for the micro-organisms .4 m Secondary Biological Treatment with Sequence Batch Reactors (SBRs) .

483 49.Heats Sludge as it is recirculated through the heat exchanges for more efficient digestion .93 m3/s.3 No.016 24.Depth = 15 metres Mechanical Sludge Thickening and Dewatering .Denis O’Sullivan. Daily Data The average daily data for 2010 is as follows below: Actual Design Flow (m3/day) 119.320 Page | 3 71.Pasteurise and Dry the Sludge Odour Control: Chemicals Scrubbers Flows    Max flow to the plant = 4.5% → 5% dry solids) .Hot Air Oven: Three belts – top middle and bottom(44% → 94% dry solids) . Max flow to PSTs from the inlet chamber 3A Max Flow to the SBRs from the PSTs = 1.Volume = 3400 m3 .190 COD Loading (kg/day) 37.792 Suspended Solids (kg/day) 17. .Dry Solids then collected and spread on agricultural land as fertiliser.231 .Mix the sludge in the digesters: It is pumped into the digesters by a gas ring at the bottom of the digester . Use of bio-gas as a fuel source for drying .974 23.Belt Press: two belts pressed against each other to squeeze water out (3% → 20% dry solids) Thermal Drying of sludge .18 m3/s. .Thin Film Evaporator . 108348006     CE 4010: Water and Wastewater .Gravity Belt: Polymers added – long chains of charged particles which attract sludge (0.Sieve (Former): Converts mass into spaghetti-like form.938 BOD Loading (kg/day) 16.

Page | 4 .Denis O’Sullivan. 108348006 CE 4010: Water and Wastewater Percentage Dry Solids The percentage dry solids at each stage are as follows: Pre-digested sludge = 5–7% Digested Sludge = 3–4% Wet cake = 20 -23 % Spaghetti = 40 – 50 % Pellets (Target) = 90 % Process Flow Diagram The process flow diagram is shown overleaf.