ANGLIAN WATER SERVICES LTD. Great Billing Wastewater Treatment Works Odour Management Plan

Transcription

1 ANGLIAN WATER SERVICES LTD. Great Billing Wastewater Treatment Works Odour Management Plan Document Approval Graham Hackney- (AWS) Catchment Manager Pat Green- (AWS) Odour Practitioner Group Date This document must be reviewed at intervals not exceeding 12 months Revision Authors Date of Issue Comments 1.0 T Hilsdon (AWS) Great Billing Treatment Manager 18/06/2008 Draft for Comment L Tuplin (AWS) 2.0 T Hilsdon (AWS) Great Billing Treatment Manager 17/08/2008 Draft for Comment L Tuplin (AWS) 3.0 T Hilsdon, Treatment Manager, Northampton 2/2/2009 To be reviewed by 2/2/2010

2 Contents Operation of Great Billing STW (GBILST) 3 Overview 3 Preliminary Treatment 3 Primary Treatment 3 Activated Sludge (Biological) Treatment 3 Final Settlement 4 Surplus Activated Sludge 4 Sludge Treatment Processes 4 Centrifuges 5 Storm Tanks 6 Sources of odour and control measures 7 Site Management Responsibilities 15 Great Billing STW Management Structure 15 Procedures for Reporting Faults 15 Identifying Maintenance and Inspection Needs 15 Replenishing Consumables 16 Receipt of Complaint 16 Action taken to resolve complaint 16 Odour Critical Plant Operation and Management 17 Operation and maintenance of odour control units 17 Odour monitoring 18 Site Operative Training 19 Spillage Management Procedures 20 Key areas at risk from spillage and control measures. 20 Record Keeping 20 Emergency Breakdown and Incident Response Planning 21 Odour Response Procedure for Great Billing STW 21 Annotated plan of Great Billing STW 23 2

3 Great Billing Odour Management Plan Operation of Great Billing STW (GBILST) Overview 1.1 GBILST serves a population equivalent of 302,000 which spans the catchment of Northampton town and surrounding villages. Treated effluent discharges into the Rive Nene. 1.2 An annotated plan of GBILST is attached as Appendix The main receptors for odour are within the immediate vicinity of Great Billing STW and are located at Cogenhoe village, Great Billing Aquadrome, the industrial estate off Crow Lane, local amenity refuse and waste disposal site off Lower Ecton Lane, the area around Lower Ecton and Lower Ecton school. Preliminary Treatment 1.4 Crude sewage gravitates to the inlet works. Earls Barton TPS rising main, also discharges into the inlet. The treatment process begins with the removal of rag and plastics using 25mm coarse mechanical screens. Grit is then removed in Detritors and transferred to skips before disposal in landfill. Following this, flow passes through three 6mm fine screens. Screenings from coarse and fine screens are collected in skips and disposed of via landfill. These processes are known as Preliminary treatment. The open channel feeding these processes has a series of odour masking spray nozzles along its length. See section 2.1, 2.2, 2.3, 2.4 and 2.5 of the action plan for future actions. Septic tankers discharge upstream of the coarse screens, emergency tankers may also discharge at this point. Primary Treatment 1.5 Preliminary treated sewage is distributed to 5 primary settlement tanks. There are a series of odour masking spray nozzles around the tanks. Settled sludge solids are removed by automatic desludge pumps, these are then pumped through 3 primary sludge strain presses for further screening and then into to a raw sludge blend tank prior to being thickened by gravity belt thickeners. Thickened sludge is then transferred to sludge holding tanks before being fed to anaerobic digestors. The desludge chambers on the primary settlement tanks are not covered and are potential odour sources, along with the primary settlement tanks. See sections 2.6 and 2.7 of the action plan. Activated Sludge (Biological) Treatment 3

4 1.6 The settled sewage from the primary settlement tanks is then delivered by gravity to the Y-split. This portions flow between the biological phosphorous removal (lanes 8, 9 and 10) and activated sludge plant (lanes 1-7). Diffused air aeration is employed in both activated sludge plants. There is little potential for odours from this area. See section 2.8 of the action plan. Final Settlement 1.7 Mixed liquor from the aeration lanes is settled by gravity in 16 circular tanks, these separate activated sludge from the treated effluent, which is discharged to the river Nene. Settled activated sludge is returned back to the aeration lanes to provide further treatment. There is little potential for odours from these sources. See section 2.9 of the action plan. Surplus Activated Sludge 1.8. Surplus Activated Sludge (SAS) is produced due to the excess growth of the micro-organisms in the aeration tanks. This is pumped to the SAS holding tank prior to transfer onto gravity belt thickeners, thickened SAS is then pumped to sludge holding tanks T1 or T2 to mix with raw thickened sludge before digestion. See section 2.10 Sludge Treatment Processes 1.9. Great Billing STW is designated as a sludge treatment centre and receives imported sludge from other sewage treatment works (STWs) in the area for treatment in addition to treating the sludge produced by the on site processes. Imported sludge is brought in by tankers and is pumped through strainpresses (screens), which remove any rag or plastics and into the sludge import tank. This sludge is then pumped to the blend tank that feeds the raw sludge thickening belts to mix with and follow the same path as the indigenous sludge. This sludge is then anaerobically digested, the digested sludge is discharged via a pipeline into sludge holding tank T4. From there it is pumped to the centrifuge sludge feed tank and fed into centrifuges to produce a thickened sludge cake. Sludge cake produced at Great Billing must be stored onsite for a minimum of 90 days to meet HACCP requirements. The sludge import tank and raw sludge blend tank had covers fitted in October During October/November 2008 odours inside the tanks will be measured to allow appropriate odour control units to be specified. The pipeline taking sludge from the digestors to tank T4 has odour control units installed at various points along its length. Intermittent odours may be due to sludge tanker discharges. The sludge cake is stockpiled in open bays and also has an odour potential. See sections 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.22 and

5 1.10. SAS is pumped into an enclosed holding tank and thickened using gravity belt thickeners. Thickened SAS treatment has been mentioned previously. Centrifuges The centrate produced from the centrifugation of the sludges is a potential source of odours but the plant is situated centrally on the site, minimising the potential for odours to reach the boundary. See sections 2.20 and 2.21 of the action plan. 5

6 Storm Tanks There are seven storm tanks, which intermittently fill during heavy rainfall, there is a potential source of odour from any sludge retained on the floor of the tanks when they empty automatically after the rainfall has abated. As part of their duties, operational staff clean the tank floor as soon as is practicably possible when the tanks have emptied. See sections 2.24 and 2.25 of the action plan. 6

7 Sources of odour and control measures Section Potential Odour Source Current control measures Future proposals Date Documents 2.1 Inlet works- off-site pumping station discharges Earls Barton TPS discharge pipe. In May 2008, Earls Barton TPS discharge pipe was extended so that the end of the pipe is below normal sewage levels in the channel, reducing risk of turbulence, aerosols and associated odours. Continued use of odour log Monday-Saturday Odour log inclusive from 01/0408 Odour masking spray nozzles around inlet usually effective at masking odours from this area. Odour log is kept at inlet works to record operation and efficacy of odour masking spray. In May 2008, pipework and nozzles replaced. 2.2 Inlet works- septic tanker discharge point Tanker discharge pipework. Odour masking spray nozzles around inlet usually effective at masking odours from this area. In May 2008, pipework and nozzles for odour spray system replaced. Continued use of odour log Monday-Saturday N/A inclusive from 01/0408 Septic tank discharge pipework at inlet works extended in October 2008 to reduce turbulence, aerosols and associated odours 2.3 Inlet works- coarse screen Odour masking spray nozzles around inlet June in N/A N/A 7

8 Skips usually effective at masking odours from this area. discussion with Biffa regarding impermeable covers for all skips on site. 2.4 Inlet works- fine screen Skips None. June in discussion with Biffa regarding impermeable covers for all skips on site. 2.5 Detritors Grit skips. None June in discussion with Biffa regarding impermeable covers for all skips on site. 2.6 Primary treatment Primary tanks Odour masking spray nozzles around primary tanks usually effective at masking odours from this area. Odour log is kept at the primary tank pumping station to record operation and efficacy of odour masking spray. Ferric sulphate dosing will be initiated during 2008/09 as part of STW improvements due to building of new sludge treatment centre. This will reduce odour by N/A N/A N/A N/A Monday-Saturday Odour log inclusive from 01/04/08 8

9 2.7 Primary treatment Desludge chambers 2.8 Biological treatment Activated sludge plants- little potential for odour 2.9 Biological treatment Final settlement tanks- little potential for odour 2.10 Surplus activated sludge Gravity belt thickeners- little potential for offensive odour. locking up any H2S that may be present in the incoming sewage. Odour masking spray nozzles around primary tanks usually effective at masking odours from this area. Odour log is kept at the primary tank pumping station to record operation and efficacy of odour masking spray. Upgrade to auto desludge pumps- due 2008/09 as part of STW improvements due to building of new sludge treatment centre. Sludge pumping regime will alter. This may reduce odour potential. Monday-Saturday Odour log inclusive from 01/0408 None None N/A N/A None None N/A N/A Existing odour control plant on the building is not working. As part of STW 2008/ /09 improvements, extra GBTs are proposed. Odour potential will be 9

10 2.11 Sludge treatment processes Sludge holding tanks T1-T Sludge treatment processes 3 strainpresses for indigenous primary sludge 2.13 Sludge treatment processes Sludge import tank 2.14 Sludge treatment processes Sludge import tank strain press skips assessed as part of this process. All tanks are covered Odour control system is unserviceable. As part of STW improvements, tanks will have mixing systems installed and odour control unit will be refurbished/replaced. None June in discussion with Biffa regarding impermeable covers for all skips on site. Tank covered Tank covered, odour control system to be specified following odour measurement None June in discussion with Biffa regarding / /2009 Ongoing N/A Tank covered N/A October Odour levels will be assessed and odour treatment plant installed following assessment. Ongoing N/A

11 impermeable covers for all skips on site Sludge treatment processes Raw sludge blend tank (pre-belt thickeners) None Tank covered, odour control unit to be specified Tank covered N/A October Odour levels will be assessed and odour treatment plant installed following assessment Sludge treatment processes Raw sludge thickening belts Odour extraction and treatment for the building. This is only partly effective. Asset Engineering team reassessing performance of odour extraction and treatment. Assessment started Sludge treatment processes Raw sludge thickening belts strain press skips None June in Ongoing N/A discussion with Biffa regarding impermeable covers for all skips on site Sludge treatment processes Digestors- the Whessoe valves None None N/A N/A 2.19 Sludge treatment processes In May 2008, odour control units were installed Monitor and record in June 2008 Site diary 11

12 Inspection chambers on pipeline delivering digested sludge to tank T Centrifuge feed tank storage The centrifuge sludge feed holding tank is not covered Centrifuge centrate Centrate returns into humus well 2.22 Sludge cake storage Sludge cake stored in bays Centrifuge/cake storage Movement of cake. on 5 chambers on pipeline. site diary off-gas from odour control units at monthly intervals. None None N/A N/A None None N/A N/A Part of cake bays have odour masking sprays New STC will produce 2009 N/A enhanced treated cake which will not need to be stored for three months to meet HACCP, thereby reducing odour potential. Potential to co-compost in this area in Will revisit odour potential as part of this scheme None Potential to cocompost in Will 12

13 2.24 Storm tanks When full Storm tanks Delay in cleaning. re-visit odour potential as part of this scheme None None N/A N/A Tanks are cleaned out as soon as practicable once empty None N/A N/A 13

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15 Site Management Responsibilities Great Billing STW Management Structure Operational Administrator Treatment Manager Great Billing Facilities Administrator Works Technician (Process Optimiser) Works Technicians (Process Controllers) Procedures for Reporting Faults 3.1 Works Technicians check plant Monday-Saturday (inclusive) and update the odour logs for the masking spray in the inlet and PST area. They inform the Treatment Manager, Optimiser or OMC Duty Manager of any issues that may cause odour problems if necessary. 3.2 The operational team are required to record in the site diary any plant breakdowns or spillages that may give rise to odour problems. 3.3 The Works Technician Optimiser will raise an M&E job if necessary to facilitate repairs. 3.4 The Treatment Manager ensures that odour control records are made available and that potential odour issues are identified and effort is made to secure investment in best practicable solutions. 3.5 The Treatment Manager will also ensure the timely replacement of spent odour control media. 3.6 The Treatment Manager will maintain dialogue with Environmental Health Officers as and when necessary. 3.7 Gt Billing STW also incorporates a Sludge Treatment Centre operated under a HACCP plan (held by the Treatment Manager). 3.8 Build up of sludge in the primary tanks may cause odours, depth of sludge in tanks is recorded on primary sludge tank depth record sheet Identifying Maintenance and Inspection Needs 3.9 Routine operational maintenance and monitoring of odour control equipment on site is carried out by Works Technicians as part of their daily duties Odour control equipment is maintained by site staff in accordance with suppliers instructions. Any additional maintenance requirements beyond the scope of operational site staff are raised as jobs on the Click system for Maintenance or Electrical personnel to carry out. If M&E personnel are 15

16 unable to resolve a problem, specialist contractors are employed. (Click is a computer based scheduling system that deploys work directly to Works Technicians laptops and records jobs completed onto a central SAP system). Replenishing Consumables 3.11 The Process Optimiser (or Process Controllers in his absence) is responsible for replenishing consumables. Receipt of Complaint 3.12 Complaints relating to Great Billing STW are directed to AWS via any of the following: Customer call into the AWS Operational Management Centre (OMC) on (24hr emergency contact) Great Billing Operations contacted direct by customer by telephone, mail or verbally at property Customer reports odour complaint via the AWS mailbox; mailbox is titled customerservices@anglianwater.co.uk Action taken to resolve complaint 3.13 The complaint is logged in the AWS SAP database; this system holds records of all customer jobs/complaints received by the company and follows a history of the actions taken. Complaints are received either by the Customer Response Manager or the Treatment Manager. Contact is then made with the customer by telephone unless otherwise requested. If the complaint is written, Anglian Water will respond in writing within 10 working days as defined in the levels of service set by OFWAT unless the complainant says that there is no need to do so: 16

17 Odour Critical Plant Operation and Management Operation and maintenance of odour control units 4.1 Odour control units on Digestor de sludge chambers. Digestor de sludge chambers are fitted with covers and extract odorous gases to OCS peacemaker units. These operate with a single duty fan in continuous run mode. Operational staff check correct fan operation daily. Faults are reported to maintenance personnel via the scheduling team. 4.2 Odour control unit sludge import tank Tank covered in October 2008; odours will be monitored during October/November 2008 and a suitable odour control unit installed. 4.3 Odour control unit blend tank for raw sludge thickening belts Tank covered in October 2008; odours will be monitored during October/November 2008 and a suitable odour control unit installed. 4.4 Odour control unit for raw sludge thickening belt building This will be upgraded and refurbished either as part of the Capital Scheme relating to the building of a new sludge treatment centre or by local Asset Engineers 4.5 Odour control unit sludge holding tanks T1, T2, T3 & T4 This will be upgraded and refurbished as necessary as part of the Capital Scheme relating to the building of a new sludge treatment centre 4.6 Odour control unit Surplus Activated Sludge thickening belt building This will be upgraded and refurbished if necessary as part of the Capital Scheme relating to the building of a new sludge treatment centre 4.7 Odour spray masking system at inlet works, Primary Settlement Tanks (PSTs) and sludge cake storage bays Works Technicians check plant Monday-Saturday (inclusive) and update the odour logs for the masking spray in the inlet and PST area. They are required to inform the Treatment Manager, Optimiser or OMC Duty Manager of any issues that may cause odour problems. 17

18 The operational team are required to record in the site diary any plant breakdowns or spillages that may give rise to odour problems. The Works Technician Optimiser will raise an M&E job if necessary to facilitate repairs. Odour monitoring 4.8 Odour monitoring is carried out on a daily basis as detailed elsewhere in this document. In addition to this, a Modeller from Thorpe Wood House regularly carries out surveys of the site by monitoring odours at designated points on the operational site and around the perimeter fence. 18

19 Site Operative Training Job role Training Completed Future training Start date Licence to Operate training.(this will include specific COTC level 4 in Waste Management modules on Treatment Manager Operations. odour control.) 2008 Treatment Manager Process Qualifications in Sewage Treatment Complete Treatment Manager Advanced Process Qualifications in Sewage Treatment Complete Works Technician (Optimiser) Works Technician (Controller) Process Qualifications in sewage treatment. Complete 08 Licence to operate training.(this will Minimum production qualifications for include specific sewage pumping, primary treatment, modules on secondary treatment. odour control.) 2008 Manufacturers training in Odour Control plant operation Licence to operate training. (This will include Minimum production qualifications for specific modules sewage pumping, primary treatment, on odour secondary treatment. control.) 2008 Licence to operate training. (This will include specific modules COTC level 4 in Waste management on odour operations. control.) 2008 Production qualification for sludge treatment and HACCP (Includes requirement for odour management plan.) 2008 Manufacturers training in Odour Control Unit plant operation Sludge Treatment Technician No sludge technicians appointed yet. 19

20 Spillage Management Procedures 6.1 All Works Technicians at Great Billing STW have a responsibility to maintain good housekeeping and clean up spillages at the earliest opportunity to prevent unnecessary odour. Anglian Water have a purchase agreement with Industrial Water Jetting Services and JK Environmental who can provide additional clean up services at short notice. Key areas at risk from spillage and control measures. 6.2 Sludge reception area. Tanker drivers instructed to clean up spillages after every load. A hose is supplied for this purpose. Entire site. Routine site inspections by Treatment Manager- a minimum of once per month. Record Keeping 7.1 Odour Monitoring Sheet for masking spray at inlet and PSTs at Great Billing 7.2 Log book recording plant breakdowns and any site issues is kept in the main office building 7.2 Results of Odour monitoring carried out by a Modeller from Thorpe Wood House are kept electronically on the Anglian Water computer system in the Gt Billing team folders 20

21 Emergency Breakdown and Incident Response Planning Odour Response Procedure for Great Billing STW Odour Critical Plant Response to breakdown (callout raised by AWS Operational Management Centre on receipt of alarm) Raw sludge Normally A3 callout if both fail. If Aquabelts. single unit fails standby plant is available, therefore different response time may be used Digester Feed Pumps Normally A4 callout. If single unit fails, standby plant is available, therefore different response time may be used Centrifuge Feed Pumps Normally A4 callout. If single unit fails, standby plant is available, therefore different response time may be used Centrifuges Normally A3 callout. If single unit fails, standby plant is available, therefore different response time may be used Sludge Import Tank Not yet installed Odour Control Unit 1 no. Forseeable consequences on odour if plant breaks down Build up of solids in primary tanks leading to increased potential for odour release Build up of solids in primary tanks & activated sludge plant due to inability to feed sludge forward Build up of solids in primary tanks & activated sludge plant due to inability to feed sludge forward Build up of solids in primary tanks & activated sludge plant due to inability to feed sludge forward 21 Actions to reduce impact Standby Plant/ Spares Person Responsible Repair fault, run second If one unit fails, second Site Operators belt as standby unit is standby. Spares sourced from supplier as required Re-set pump or run standby Standby pump Site Operators available. Spares sourced from supplier as required Use standby feed pump Standby pump available. Spares Site Operators sourced from supplier as required Use standby centrifuge Standby unit available. Spares sourced from Site Operators supplier as required

22 Raw sludge thickening belt feed tank Odour Control Unit Inlet, PST & sludge cake bays odour masking spray system Digestor Odour Control Unit Odour control unit on tanks T1 to T4 Odour control unit on Raw sludge building Odour control unit on Activated sludge building Not yet installed Normally A2 callout Potential for increase dependant on weather conditions Repair as soon as possible Temporary portable odour spray unit (pump + IBC) kept on site Normally A2 callout Immediate odour source Repair plant Source spares from supplier Not yet refurbished & operational Being upgraded as part on the Capital scheme/ by Operational Capital team Not yet refurbished & operational This document is for daily use and reference by Great Billing Site Operators RESPONSE CODES: A0-within 1 hour, A1-within 4 hours, A2-within 1 day, A3-next day, A4-next 2 days 22 Site Operators Site Operators

23 Annotated plan of Great Billing STW Appendix 1: Annotated Plans of Great Billing Sewage Treatment Works Inlet works Digestors Primary Tanks Sludge cake storage bays

24 24 Sludge cake storage bays