assimilation capacity study of river erne to accept ...be ceng miei diposh gradiosh hdipbs &...
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1
Farragh Proteins
Location:
Monery
Crossdoney
Co. Cavan
IPPC Register Number:
P0025-04
Issue Date of Report:
01st April 2011
Consultants:
Tom Rowan BE CEng MIEI DipOSH GradIOSH HDipBS
&
John Lynch BSC MSc AIEMA
Rowan Engineering Consultants Ltd.
58 Academy Street
Navan
Co. Meath
Tel: 046-9030102
Web: www.rec.ie
Email: [email protected]
Assimilation Capacity Study of River Erne to Accept
Proposed Treated Effluent from Farragh Proteins
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DOCUMENT CONTROL SHEET
CLIENT FARRAGH PROTEINS
PROJECT TITLE
Assimilation Capacity of River Erne
DOCUMENT NO. FARRAGH WAC 2011-01
VER STATUS AUTHOR REVIEWED BY APPROVED BY ISSUE DATE
01 DRAFT TOM ROWAN JOHN LYNCH TOM ROWAN 20/2/2011
02 FINAL TOM ROWAN JOHN LYNCH TOM ROWAN 1/4/2011
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Table of Contents Page No.
1. INTRODUCTION ....................................................................................................................................................... 4
1.1 BACKGROUND INFORMATION ............................................................................................................................................. 4
1.2 PROPOSED CHANGES TO EFFLUENT FLOWS AND QUALITY ......................................................................................................... 4
1.3 METHODOLOGY OF WASTE ASSIMILATION CAPACITY (WAC) .................................................................................................. 4
2. CURRENT WASTEWATER TREATMENT PLANT (WWTP) AND IPPC LICENCE REQUIREMENTS .................................... 5
3. BAT AND BREF GUIDANCE ....................................................................................................................................... 7
4. PRESENT WATER QUALITY OF RIVER ERNE .............................................................................................................. 8
5. REQUIRED WATER QUALITY OF IRISH RIVERS .......................................................................................................... 9
6. REQUIRED WATER QUALITY OF RIVER ERNE .......................................................................................................... 10
7. WASTE ASSIMILATION CAPACITY (WAC)................................................................................................................ 11
5.1 ASSIMILATION CAPACITY & MIXING CALCULATIONS OF EXISTING RIVER QUALITY ........................................................................ 11
5.2 ASSIMILATION CAPACITY & MIXING CALCULATIONS OF NOTIONALLY CLEAN RIVER ..................................................................... 12
8. CONCLUSION ......................................................................................................................................................... 13
REFERENCES .............................................................................................................................................................. 14
APPENDIX A – EPA MONITORING LOCATION MAP .......................................................................................... 15
APPENDIX B – CAVAN COUNTY COUNCIL RIVER ERNE ANALYSIS .............................................................. 17
APPENDIX C – REC RIVER ERNE ANALYSIS CERTIFICATES .......................................................................... 19
APPENDIX D – COMBINED ANALYSIS OF RIVER ERNE .................................................................................... 27
APPENDIX E – WAC CALCULATIONS FOR EXISTING RIVER ERNE .............................................................. 28
APPENDIX F– MIXING CALCULATIONS FOR EXISTING RIVER ERNE .......................................................... 29
APPENDIX G – WAC CALCULATIONS FOR NOTIONALLY CLEAN RIVER ERNE ........................................ 30
APPENDIX H – MIXING CALCULATIONS FOR NOTIONALLY CLEAN RIVER ERNE ................................... 31
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1. Introduction
1.1 Background information
Rowan Engineering Consultants (REC) were contracted to carry out an assimilative capacity study
(ACS) on behalf of Farragh Proteins on the River Erne adjacent to their Wastewater Treatment
(WWTP) discharge location. Farragh Proteins obtained their reviewed IPPC licence No. P0025-04
from the Agency in 2007 under Section 90(2):‘The disposal or recycling of animal carcasses and
animal waste with a treatment capacity exceeding 10 tonnes per day.’
A rendering facility has been in operation at this site since 1951. Farragh Proteins took over this
facility in 2004 and have invested heavily in upgrading it to adhere with BAT and BREF guidelines.
The Farragh Proteins IPPC license currently permits them to discharge 240m3 of effluent per day to the
River Erne in accordance with maximum emission limit values (ELV’s). Farragh Proteins propose to
install extra condensing and air abatement systems into their process. These systems will condense
some of the vapours, converting the vapour into wastewater which will be treated by the WWTP in
accordance with agreed ELV parameters.
1.2 Proposed changes to effluent flows and quality
The proposed changes to the abatement systems above will increase the quantity of wastewater to be
treated and discharged to the River Erne. It is expected that the flow will increase from 240m3/day to
340m3/day. However Farragh Proteins want to reduce the amount of Ammonia discharged to the River
Erne and propose to reduce the Ammonia ELV in their IPPC license from 25mg/l to 10mg/l. They
propose that all other parameter ELVs remain the same. We used the following ELVs in the
assimilation capacity study calculations.
• Discharge flow of 340m3/day
• Ammonia ELV of 10mg/l
• All other ELVs remain the same
1.3 Methodology of Waste Assimilation Capacity (WAC)
The WAC has been carried out in accordance with the following legislation and guidelines:
• WSTG – ‘Guidance to Application for a Licences to Discharge to Surface Waters’
• European Communities Environmental Objectives (Surface Waters) Regulations 2009
The analysis carried out on the River Erne consists of a combination of samples and analysis by the
EPA, Cavan County Council and Rowan Engineering Consultants Ltd (REC).
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2. Wastewater Treatment Plant (WWTP) and IPPC Licence
requirements
The WWTP at Farragh Proteins consists of preliminary, secondary and tertiary treatment prior to
discharge.
Preliminary Treatment
The raw effluent enters a grease trap and is then pumped to a 2mm rotary drum screen. The screened
effluent gravity flows into a concrete balancing tank. The balanced effluent is then pumped through a
chemical DAF to remove fats, oils and greases and excess BOD and suspended solids before flowing
into a 706m3 balancing tank. A new 1004m
3 balancing tank will replace the existing tank.
Secondary Treatment
The balanced effluent is currently forward fed to a 726m3 anoxic tank where the Nitrates are broken
down, before gravity feeding to 2 No. aeration tanks (1,432m3) in series to remove BOD and
Ammonia. An additional 1004m3
aeration tank will be constructed increasing the aeration capacity to
2436m3. The aerobically treated effluent is then settled in a large clarifier.
Tertiary Treatment
The settled treated effluent is stored in a buffer tank before being passed through a sand filter.
Capacity of the Wastewater Treatment Plant
The limiting factor in the wastewater treatment plant is the breakdown of Ammonia in the aeration
tanks and Nitrates in the anoxic tank. Farragh Proteins has a proposed aeration capacity of 2436m3 and
an anoxic capacity of 726m3. The proposed flow of 340m
3 day will allow 2.1 days anoxic treatment
and 7.1 days aeration. These retention times indicate the WWTP should be more than capable of
treating the proposed effluent.
The treated effluent from the sand filter (Emission point reference number: SW1) currently adheres to
the emission limit values (ELV’s) which are outlined in Schedule B2 of their IPPC Licence and table 1
below.
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Parameter Units Emission Limit Value
(ELV)
Maximum Daily Flow m3/day 240
Maximum Hourly Flow m3/hr
10
Temperature oC Not increase river temp by
1.5oC or >22
oC
pH pH units 6-9
BOD mg/l 20
Suspended Solids mg/l 25
Nitrates (as N) mg/l 15
Ammonia (as N) mg/l 25
Total Phosphorus (as P) mg/l 2
Oils, Fats & greases mg/l 15
Table 1: Farragh Proteins SW1 Emission limit Values as outlined in IPPC licence P0025-04
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3. BAT and BREF Guidance
The EPA published a ‘BAT Guidance Note On Best Available Techniques for the Disposal or
Recycling of Animal Carcasses and Animal Waste’. This document is based on and references the
European Communities ‘Integrated Pollution Prevention and Control Reference Document on Best
Available Techniques in the Slaughterhouses and Animal By-products Industries May 2005’. The
wastewater treatment system in Farragh Proteins described in section 1 above adheres to the BREF
guidelines. The BAT guidance provides appropriate emission limit values for a rendering facility. The
existing IPPC ELV’s adhere to the BAT guidance document as can be seen in table 2 below.
Parameter units BAT Emission Level FP IPPC ELV
pH pH units 6-9 6-9
BOD mg/l >90% removal, or 20
- 40mg/l
20
Suspended Solids mg/l 50 25
Nitrates (as N) mg/l 15
Ammonia (as N) mg/l 10 - 25 25
Total Phosphorus (as P) mg/l >80% removal3
, or
0.5 - 2mg/l
2
Oils, Fats & greases mg/l 10 - 15 15
Table 2: Farragh Proteins SW1 ELV’s compared with BAT guidelines
The proposed change in Ammonia ELV from 25mg/l to 10mg/l will ensure Farragh Proteins are
discharging to the minimum emissions recommended in BAT.
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4. Present Water Quality of River Erne
The River Erne has a catchment area of approx 318km2 and stretches from Beaghy Lough, two miles
south of Stradone to Loch Gowna, Lough Oughter, Lough Erne (Upper and Lower) and discharges to
the sea at Ballyshannon. The Office of Public Works (OPW) has a hydrometric station located at
Bellahillan Bridge on the River Erne approx 950m prior to the emission point (SW1) from Farragh
Proteins (See Appendix A). The OPW provided us with 95%ile and 50%ile flow rates for the River
based on records from 1955 to 2005 (See Appendix B). This provided us with a 95%ile flow rate of
0.45m3/s (1,620m
3/hr) and a 50%ile flow rate of 4.28m
3/s (15,408m
3/hr). Biological and chemical
monitoring is also carried out at this station by Cavan County Council (See Appendix B.3 and table 4
below). Rowan Engineering Consultants also took 4 No. grab samples of the river 100m upstream
from SW1 and analysed them for BOD, Ammonia, Nitrate, ph, Total Phosphate, Ortho Phosphate and
suspended solids (See Appendix C). The average analysis of the Cavan County Council 2010 analysis
and REC 2011 analysis was used for the assimilation capacity calculations (See Appendix D).
EPA biological monitoring of the River Erne at Bellahillan Bridge since 1997 can be seen in table 4
and Appendix B.2 below. This shows that the Q-Rating of the river has deteriorated slightly from Q4
in 1997 to Q3-4 in 2010.
Q- Biological Rating
Location Station No. 2010 2007 2004 2001 1998 1997
Bellahillan Bridge 36011 / 1100 3-4 3-4 4 4 4 4
Table 3: Recent Biological Water Quality Monitoring of River Erne 1.
The River Erne c.500m upstream of the Farrgh Proteins discharge to Lough Oughter is part of the
Lough Oughter Special Protection Area (SPA) (Site code: 004049). Furthermore, the River Erne from
Bellahillan Bridge to Lough Oughter is part of the Lough Oughter and Associated Loughs proposed
National Heritage Area (Site code: 000007).
The Lough Oughter SPA is of importance for both wintering and breeding birds. Of particular note is
the internationally important population of Whooper Swan that is based in the area. The site also
supports nationally important populations of a further four wintering species including the Great
Crested Grebe
1 Results extracted from Agency’s ENVision Maps
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5. Required Water Quality of Irish Rivers
The most recent Irish legislation set down as part of the Water Framework Directive to provide
guidelines for river water quality in Ireland is SI No. 272 of 2009 known as ‘The European
Communities Environmental Objectives (Surface Waters) Regulations 2009’. The Surface Water
regulations provide targets for water quality on 22nd
December 2015, based on the existing water
quality.
Section 28.2 states “A surface water body whose status is determined to be less than good (or good
ecological potential and good surface water chemical status as the case may be) when classified by the
agency in accordance with these regulations shall be restored to at least good status (or good
ecological potential and good surface water chemical status as the case may be) by not later than 22nd
December 2015 unless otherwise provided for by these regulations.”
These target values are included in schedule 5 and include:
• Biological quality elements
• Oxygenation conditions (BOD)
• Nutrient conditions (Ammonia and Phosphorous)
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6. Required Water Quality of River Erne
Schedule 5 of the Surface Water Regulations is included as table 4-5 below, with the appropriate
targets for the River Erne highlighted in orange.
Oxygenation Conditions (Biological Oxygen Demand)
Oxygenation Conditions River Water Body
BOD mg O2/l High Status <1.3 (mean) or <2.2 (95%ile)
Good Status <1.5 (mean) or <2.6 (95%ile)
Table 4: Oxygenation Conditions
Nutrient Conditions
Nutrient Conditions River Water Body
Total Ammonia (mg N/l) High Status <0.040 (mean) or <0.090 (95%ile)
Good Status <0.065 (mean) or <0.140 (95%ile)
Molybdate Reactive Phosphorous
(MRP) (mg/l)
High Status <0.025 (mean) or <0.045 (95%ile)
Good Status <0.035 (mean) or <0.075 (95%ile)
Table 5: Nutrient Conditions
The above tables inform us that if the River Erne is to have a river quality of ‘Good Status’ it will
require to have the following conditions at 95%ile flow rate:
• BOD of 2.6mg/l
• Total Ammonia of 0.14mg/l
• Molybdate Reactive Phosphorous of 0.075mg/l
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7. Waste Assimilation Capacity (WAC)
The definition of assimilative capacity, as used by the Environmental Protection Agency (EPA), is ‘the
ability of a body of water to cleanse itself; its capacity to receive waste waters or toxic materials
without deleterious effects and without damage to aquatic life or humans who consume the water’
(Ref. 7.10). Guidance issued by the EPA and Water Services Training Group on the assessment of
assimilative capacity was used in this project. The guidance details the following:
a. Assess the assimilative capacity with respect to BOD, Ammonia and Orthophosphate
(P), in accordance with S.I. No. 272 of 2009 (Surface Water Regulations) using the
following calculation.
Assimilative capacity = (Cmax - Cback) x F95 x 86.4kg/ day
Where Cmax = maximum permissible concentration (mg/l)
Cback = background upstream concentration (mg/l)
F95 = 95%ile flow in river/ stream (m3/s)
b. Assess the impact of the treated effluent on the River using the mixing calculation:
Downstream C = (Upstream flow x upstream C) + (discharge flow x discharge C)
Upstream flow + discharge flow
5.1 Assimilation Capacity & Mixing Calculations of existing river quality
An assimilative capacity assessment was carried out for a potential discharge of 340m3/day to
determine if the River Erne had the assimilative capacity to accept the proposed discharge. The 95%ile
flow rate was used for all parameters. The waste assimilation capacity and mixing calculations can be
seen in Appendix E & F. The results are summarised in table 6 below.
Parameter Assimilative
Capacity of Erne
(kg/d)
Proposed
discharge
(kg/day)
Existing River
Quality (mg/l)
Predicted
Downstream
quality (mg/l)
Surface Water
Quality Standards
(mg/l)
BOD 52.49 6.8 1.25 1.41 2.6
Ammonia 4.24 3.4 0.03 0.117 0.14
Ortho P 1.29 0.47 0.0419 0.053 0.075
Table 6: Waste Assimilation Capacity & Mixing Calculations of River Erne.
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Based on the proposed final effluent analysis and on an estimated 95%ile flow rate of 0.45m3/s, the
mixing capacity of the River Erne is sufficient to meet the water quality targets for BOD, Ammonia
and Orthophosphates to ensure the River Erne can attain Good Quality status by 2015 in accordance
with the Surface Water Regulations. It should be noted that by reducing the Ammonia ELV from
25mg/l to 10mg/l Farragh Proteins will actually reduce the amount of Ammonia discharged from the
WWTP by 43% from 6kg/day to 3.4kg/day.
5.2 Assimilation Capacity & Mixing Calculations of Notionally Clean River
Assuming that the river management plan upstream will be capable of providing a notionally clean
river then the river could be expected to have a future upstream river quality of BOD – 0.26mg/l,
Ammonia – 0.008mg/l and Orthophosphates of 0.005mg/l. I also carried out an assimilative capacity
assessment for a potential discharge of 340m3/day on a notionally clean River Erne. The waste
assimilation capacity and mixing calculations can be seen in Appendix G & H. The results are
summarised in table 7 below.
Parameter Assimilative
Capacity of Erne
(kg/d)
Proposed
discharge
(kg/day)
Existing River
Quality (mg/l)
Predicted
Downstream
quality (mg/l)
Surface Water
Quality Standards
(mg/l)
BOD 90.98 6.8 0.26 0.43 2.6
Ammonia 5.13 3.4 0.008 0.09 0.14
Ortho P 2.72 0.47 0.005 0.02 0.075
Table 7: Waste Assimilation Capacity & Mixing Calculations of Notionally Clean River Erne.
This shows that if the upstream river plan is successful then Farragh Proteins discharge would have
even less of an effect on the River Erne.
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8. Conclusion
The EPA/OPW Bellahillan station provided us with detailed flow rates, biological and chemical
analysis of the River Erne. We combined the above with four sample analysis carried out by REC to
determine average background concentrations for the River Erne.
We used the discharge ELVs proposed by Farragh Proteins to determine the overall daily
concentrations to be discharged. These ELVs included:
• Increased discharge flow of 340m3/day.
• Reduced Ammonia ELV to 10mg/l.
• All other ELVs remain the same.
By reducing the Ammonia ELV from 25mg/l to 10mg/l Farragh Proteins will actually reduce the
amount of Ammonia discharged from the WWTP to the River Erne by 43% from 6kg/day to
3.4kg/day. This will have a positive effect on the River Erne.
We then used the following legislation and guidelines to determine the waste assimilation capacity of
the River Erne.
• WSTG – ‘Guidance to Application for a Licences to Discharge to Surface Waters’
• European Communities Environmental Objectives (Surface Waters) Regulations 2009
Based on the proposed final effluent ELV concentrations and a 95%ile flow rate of 0.45m3/s, the
mixing capacity of the River Erne is sufficient to meet the water quality targets for BOD, Ammonia
and Orthophosphates to ensure the River Erne can attain Good Quality status by 2015 in accordance
with the Surface Water Regulations.
Signed: Dated: 01st April 2011
Tom Rowan John Lynch
BE CEng MIEI DipOSH GradIOSH HDipBS BSc MSc AIEMA
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References
Description
1) Water Services Training Group. (2010) Applicant Guidance – Application for a
Licence to Discharge to Surface Waters.
2) European Communities Environmental Objectives (Surface Waters) Regulations
2009
3) Higgins, B. (2006) Assimilative Capacity and Licence Conditions presented at EPA
National Water Conference 13th
June 2006. Office of Licensing and Guidance,
Environmental Protection Agency
4) EPA (2007). Estimated Dry Weather Flow & 95percentile Flow. EPA
5) EPA (2001). Parameters of Water Quality Interpretation and Standards
6) www.epa.ie Environmental Protection Agency website
7) www.met.ie Met Eireann website
8) www.gsi.ie Geological Survey of Ireland
9) IPPC Licence No. P0025-04
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Appendix A – EPA Monitoring Location Map
Bellahillan
Bridge
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Appendix B.1 – OPW Flow Data on the Erne at Bellahillan Bridge
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Appendix B.2 –Biological River Quality
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Appendix B.3 – Cavan County Council River Erne Analysis
EntityName StationName
Station Local Code
Sample Date
Ammonium (N) mg/l BOD mg/l
Ortho-phosphate (mg/l as P)
ERNE Bellahillan Br 1100 15/04/2010 0.01 3 0.01
ERNE Bellahillan Br 1100 01/07/2010 0.037 <2 0.061
ERNE Bellahillan Br 1100 21/10/2010 0.014 <2 0.057
ERNE Bellahillan Br 1100 14/12/2010 2 0.038
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Appendix C – REC River Erne Analysis Certificates
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Appendix D – Combined Analysis of River Erne
EntityName Sampler Station Name Station Code
Sample Date
Ammonium (N) mg/l
BOD mg/l
Nitrates (N) mg/l
Ortho-p (mg/l as
P)
Total P
(mg/l) P
Ratio pH TSS
ERNE Cavan CC Bellahillan Br 1100 15/04/2010 0.01 3 0.277 0.01 8.1
ERNE Cavan CC Bellahillan Br 1100 01/07/2010 0.037 1 0.183 0.061 7.73
ERNE Cavan CC Bellahillan Br 1100 21/10/2010 0.014 1 0.341 0.057 7.79
ERNE Cavan CC Bellahillan Br 1100 14/12/2010 1 0.93 0.038 6.9
ERNE REC Farragh Proteins Upstream 26/01/2011 0.017 1 1.13 0.04 0.057 0.7017544 7.6 1
ERNE REC Farragh Proteins Upstream 02/02/2011 0.019 1 0.95 0.034 0.046 0.7391304 7.5 1
ERNE REC Farragh Proteins Upstream 09/02/2011 0.069 1 1.71 0.06 0.092 0.6521739 7.5 3
ERNE REC Farragh Proteins Upstream 16/02/2011 0.05 1 1.85 0.035 0.059 0.5932203 7.4 1
Average 0.03 1.25 0.92 0.042 0.064 0.672 7.57 1.50 * BOD & SS Figures of less than 2 are shown as 1mg/l
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Appendix E – WAC calculations for existing River Erne
Parameters used in calculations Units BOD NH3-N Ortho P
Effluent Concentration based on IPPC ELV's mg/l 20 10 1.396
Effluent Volume m3/day 340 340 340
Effluent Volume m3/s 0.0039 0.0039 0.0039
Weight of parameter discharged per day kg/day 6.8 3.4 0.47464
Regulation requirement mg/l 2.6 0.14 0.075
River Concentration as per laboratory analysis mg/l 1.25 0.03 0.0419
95%ile River Flow F95 m3/s 0.45 0.45 0.45
50%ile River Flow F50 m3/s 4.28
Notes:
*BOD samples of <2 were taken as 1mg/l
Discharge Ortho P based on Total P *0.698 as per laboratory analysis.
Ortho P permitted based on moderate quality river in 2009 requiring to be good quality by 2015.
WAC of River C max mg/l 2.6 0.14 0.075
C back mg/l 1.2500 0.0309 0.0419
F 95 m3/sec 0.45 0.45 0.45
Multiplying factor 86.4 86.4 86.4
WAC = (Cmax- C back) * F 95 x 86.4kg/day) kg/day 52.49 4.24 1.29
Maximum Flow permitted at expected concentration m3/day 2624.4 424.347429 922.56447
% of capacity to be assimilated at proposed discharge rate 13% 80% 37%
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Appendix F– Mixing calculations for existing River Erne
River Quality after Mixing Calculation
Using 95%ile/50%ile Flow Units BOD NH3-N Ortho P
(Effl conc * Effl vol) + (Median River conc x River Flow 95/50%) 0.641204 0.053238 0.024337
River flow 95% + Effl vol 0.4539 0.4539 0.4539
Permitted under appropriate Regulations mg/l 2.6 0.14 0.075
Existing River Concentration as per laboratory analysis mg/l 1.25 0.03 0.041875
Final River Concentration mg/l 1.4125 0.1173 0.0536
Change in river concentration mg/l 0.1625 0.0864 0.0117
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Appendix G – WAC calculations for notionally clean River Erne
Parameters used in calculations Units BOD NH3-N Ortho P
Effluent Concentration based on IPPC ELV's mg/l 20 10 1.396
Effluent Volume m3/day 340 340 340
Effluent Volume m3/s 0.0039 0.0039 0.0039
Weight of parameter discharged per day kg/day 6.8 3.4 0.47464
Regulation requirement mg/l 2.6 0.14 0.075
Notional clean river values provide by the EPA mg/l 0.26 0.008 0.0050
95%ile River Flow F95 m3/s 0.45 0.45 0.45
50%ile River Flow F50 m3/s 4.28
Notes:
*BOD samples of <2 were taken as 1mg/l
Discharge Ortho P based on Total P *0.698 as per laboratory analysis.
Ortho P permitted based on moderate quality river in 2009 requiring to be good quality by 2015.
WAC of River C max mg/l 2.6 0.14 0.075
C back mg/l 0.2600 0.0080 0.0050
F 95 m3/sec 0.45 0.45 0.45
Multiplying factor 86.4 86.4 86.4
WAC = (Cmax- C back) * F 95 x 86.4kg/day) kg/day 90.98 5.13 2.72
Maximum Flow permitted at expected concentration m3/day 4548.96 513.216 1949.5702
% of capacity to be assimilated at proposed discharge rate 7% 66% 17%
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Appendix H – Mixing calculations for notionally clean River Erne
River Quality after Mixing Calculation
Using 95%ile/50%ile Flow Units BOD NH3-N Ortho P
(Effl conc * Effl vol) + (Median River conc x River Flow 95/50%) 0.195704 0.042952 0.007744
River flow 95% + Effl vol 0.4539 0.4539 0.4539
Permitted under appropriate Regulations mg/l 2.6 0.14 0.075
Notional clean river values provide by the EPA mg/l 0.26 0.008 0.005
Final River Concentration mg/l 0.4311 0.0946 0.0171
Change in river concentration mg/l 0.1711 0.0866 0.0121
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Appendix 7.4 Groundwater Results
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1
Farragh Proteins
Location:
Farragh Proteins
Monnery Upper
Crossdoney
Co. Cavan
Date of Report:
16th
December 2011
Consultant:
Tom Rowan BE CEng MIEI DipOSH GradIOSH HDipBS
Rowan Engineering Consultants Ltd.
58 Academy Street
Navan
Co. Meath
Tel: 046-9030102
Web: www.rec.ie
Email: [email protected]
Review of capacity of proposed Waste Water
Treatment Plant to treat wastewater
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2
Table of Contents
1. INTRODUCTION .............................................................................................................................................. 3
2. BACKGROUND INFORMATION .................................................................................................................. 3
2.1 EXPECTED PRODUCTION .................................................................................................................................. 3 2.2 EXPECTED EFFLUENT PRODUCTION ................................................................................................................. 3
2.2.1 Current effluent produced ...................................................................................................................... 3 2.2.2 Extra production proposed .................................................................................................................... 3 2.2.2 Extra effluent proposed .......................................................................................................................... 3
2.3 EXPECTED EFFLUENT CONCENTRATIONS ......................................................................................................... 4 2.4 IPPC LICENSE DISCHARGE PARAMETERS ........................................................................................................ 4
3. DESIGN OF THE WWTP ................................................................................................................................ 5
3.1 GREASE TRAP .................................................................................................................................................. 8 3.2 ROTARY SCREEN .............................................................................................................................................. 8 3.3 CONCRETE SUMP ............................................................................................................................................. 8 3.4 COLLEGE PROTEIN CHEMICAL DAF ................................................................................................................ 8 3.5 BALANCING TANK – NEW TANK NO. 10 .......................................................................................................... 9 3.6 ANOXIC ZONE (TANK NO. 2).......................................................................................................................... 10 3.7 AERATION ZONE (TANKS NO. 3, 1 & 9) ......................................................................................................... 11 3.8 CHEMICAL PRECIPITATION ............................................................................................................................. 13 3.9 CLARIFIER ...................................................................................................................................................... 13 3.10 SLUDGE TANK ........................................................................................................................................... 14 3.11 DEWATERING DECANTER .......................................................................................................................... 14 3.12 SAND FILTER ............................................................................................................................................. 15 3.13 DISCHARGED TREATED WATER ................................................................................................................. 15
4. MONITORING AND ANALYSIS ................................................................................................................. 15
5. MANAGEMENT, OPERATION & TRAINING .......................................................................................... 15
6. MAINTENANCE ............................................................................................................................................. 16
7. CONCLUSION................................................................................................................................................. 16
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1. Introduction Farragh Proteins is a rendering facility located in Crossdoney Co. Cavan. The facility proposes to
upgrade one of the technical processes and several of the abatement systems including the wastewater
treatment plant (WWTP) at the facility. The proposed technical changes to the site will increase the
amount of wastewater produced from 240m3/ day to 340m
3/day. I inspected the wastewater treatment
plant and met with John Gilroy and Lisa Clarke from Farragh Proteins to review if the proposed
upgraded wastewater treatment plant would have adequate capacity for the proposed increase in
wastewater produced. The infrastructural changes to the existing WWTP are to replace the existing
706m3 balancing tank with a 1,000m
3 balancing tank and to construct an additional 1,000m
3 aeration
tank.
2. Background Information
2.1 Expected Production
An annual production of 125,000MT is expected at the facility.
2.2 Expected Effluent Production
2.2.1 Current effluent produced
Farragh Proteins currently discharge a maximum of 240m3/day effluent to the River. This is equivalent
to 1,680m3/week.
2.2.2 Extra production proposed
The process upgrade to low temperature rendering in line 3 will produce a maximum of 2,270m3 of
production wastewater per week.
2.2.2 Extra effluent proposed
Maximum rainfall in Clones usually occurs in October, with a mean rainfall of 97mm and we have
assumed a maximum rainfall of 48.5mm per week in our calculations. The environmental principle of
diverting rainwater to stormwater drains rather than effluent drains means that modern building and
yard design should minimise the amount of rainwater diverted to the WWTP. The current facility will
provide a WWTP and a factory dirty yard area of 3,270m2which will drain directly to the WWTP.
Assuming a maximum weekly rainfall of 48.5mm per week and a run off coefficient of 0.7 this would
produce an extra 110m3 of effluent per week (0.048m*0.7*3,270m
2).
The combined effect of this is that Farragh Proteins could produce discharge up to 2,380m3 of effluent
per week. As a result the maximum daily amount discharged will be 340m3/day at a maximum rate of
15m3/hr.
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2.3 Expected Effluent Concentrations
Farragh Protein carries out daily analysis of the effluent at various stages throughout the process. The
raw effluent in the balancing tank which is forward fed to the biological system is used to design the
WWTP. The effluent produced after the proposed upgrade will have a similar concentration to the
existing effluent which is shown in table 1 below.
Date COD BOD SS NH3-N Total P
mg/l mg/l mg/l mg/l mg/l
After DAF 6,000-10,000 2100 2,500-4,000 800-1,500 <200
Table 1: Expected Effluent Concentrations
2.4 IPPC License Discharge Parameters
Table 2 below outlines the discharge emission limit values (ELVs) we are proposing for the IPPC
application review. The current IPPC license permits a discharge of 240m3/day and a maximum total
Ammonia of 25mg/l. Following our waste assimilation capacity assessment in Appendix 7.1 we
propose that the maximum ELV for flow is increased to 340m3/day and the Ammonia ELV is reduced
to 10mg/l. This has been included in our application to the EPA for the IPPC license review.
Parameter Existing ELV Proposed ELV
pH 6-9 6-9
Temperature (°C) < 22 < 22
B.O.D. (mg/L) 20 20
S.S. (mg/L) 25 25
Nitrate as N (mg/L) 15 15
Total Ammonia as N (mg/L) 25 10
Total Phosphorous as P (mg/L) 2 2
Oils, fats and greases (mg/L) 15 15
Max Daily Flow (m3) 240 340
Max Flow per hour(m3) 10 15
Table 2: IPPC license - Emission limit values (ELVs).
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3. Design of the WWTP The existing and proposed Wastewater Treatment system consists of:
o Grease Trap To remove raw grease and fat
o Rotary Screen To pre-screen effluent and remove heavy solids and rags
o Raw Sump Sump to hold raw effluent and pump to the balancing tank
o Chemical DAF To control the loading to the biological system
o Balancing Tank To equalise the effluent before biological treatment
o Anoxic Zone To remove Nitrates and total Nitrogen
o Aeration Tanks To remove BOD, COD and Ammonia (NH3-N)
o Chemical Dosing To remove phosphorous
o Clarifier To separate the treated liquid from the solids.
o Supernatant Tank Store treated effluent for sand filter
o Sand Filter Tertiary treatment of final effluent
o Decanter To dewater sludge
The expected removal rates from the proposed WWTP can be seen in Table 3 below. The removal
rates will be explained throughout this section and are consistent with the existing removal rates of the
WWTP.
Date COD BOD SS NH3-N NO3-N Total P FOG
Stage mg/l mg/l mg/l mg/l mg/l mg/l mg/l
After Screen 15,000-20,000 <10,000 8,000-12,000 1,000-2,400 300-500
After DAF 6,000-10,000 2100 2,500-4,000 800-1,500 <200
Discharge 90-130 <20 <25 <10 <9 <1.7 <10Table 3: Expected removal rates of WWTP.
A flow diagram of the proposed WWTP can be seen on the following page.
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Proposed WWTP Flow Diagram (Proposed tanks shaded blue) No Tanks 3 on the
diagram? Is the capacity for Tank 1 & 4 right?
Rotary Screen
30m3/hr
Balance Tank (T10)
1004m3
Chemical DAF
30m3/hr
Anoxic Zone (T2)
726m3
Clarifier
9.5m Diam
Sludge Tank (T7)
20m3
Decanter
10m3/hr
River Erne
Sludge
Grease Trap
Concrete Sump
200m3
Aeration Tank (T9)
1004m3
Supernatant Tank
(T6) 200m3
Sand Filter
20m3/hr
Aeration Tank (T3)
706m3
Existing Tank
Proposed Tank
Sludge
Effluent
Water
Aeration Tank (T1)
726m3
NC Influent
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3.1 Grease Trap
Volume 3m3
Sump Pumps 2 No. 20m3/hr Variable Speed drive pumps
An existing grease trap is used to remove the readily available fats, oils and grease from the effluent.
The grease is removed from the tank by an auger. There is adequate capacity for the proposed effluent.
3.2 Rotary Screen
Maximum Capacity 30m3/hr
Screen Width 1.5mm
The effluent from the grease trap is pumped up to the existing 30m3/hr rotary screen. The existing
30m3/hr capacity of the DAF is double the required capacity. The heavy solids are removed in the
screen mesh while the liquid effluent gravity flows into the concrete sump. Existing removal rates of
10% of influent COD, BOD, SS and 20% of FOG’s are achieved. The screened material will be
diverted to a waste bin for disposal as CAT 1 material.
3.3 Concrete Sump
Sump dimensions 10m, 5.4m by 4.5m deep
Total Volume 243m3
Working Volume 216m3
Sump Pumps 2 No. 30m3/hr Variable Speed drive pumps
Mixer 1 No. 24kW compressor and diffused aeration
The concrete sump acts as a balancing tank prior to the chemical DAF. The effluent is mixed with
diffused air. The effluent is pumped from the concrete sump to the chemical DAF.
3.4 College Protein Chemical DAF
Maximum Capacity 30m3/hr
Volume 10m3
Internal Equipment Flocculant, Coagulant and ph pipe dosing system
The inconsistency of the incoming effluent requires a chemical DAF which can reduce incoming
loading by 75-80%. A College Proteins manufactured DAF with chemical dosing and pipe mixing
system flocculates and coagulates the organic material. The existing 30m3/hr capacity of the DAF is
double the required capacity. The dose rate and the scraper speed can be controlled to increase or
decrease the food required to the bacteria in the biological system.
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3.5 Balancing Tank – New Tank No. 10
Type Concrete Tank
Dimensions Int. Diam = 17.66 m and height = 4.5m, WH=4.1m
Total Volume 1,102m3
Working Volume 1,004m3
Mixing 1 No. 45kW diffused aeration system
Forward Feed Pumps 2 No duty/standby V.S.D of 5-30m3/hr pumps
The inconsistency of the incoming effluent requires equalisation in a balancing tank prior to pumping
to the biological system. The existing 706m3balancing tank (Tank No. 4) would provide 2 days
retention. As a result it will be replaced by the new 1,004m3 balancing tank (Tank No. 10) to increase
retention and operate consistently over bank holiday weekends.
Retention
The 1,004m3 balancing tank will have the capacity to hold three full days of effluent.
Mixing
The diffused aeration will ensure that the effluent will be kept mixed and homogenised. This will also
prevent settlement and a crust forming on the surface.
Forward Feed
The forward feed pumps are designed to allow flexibility in feeding the biological plant, while
maintaining energy efficiency.
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3.6 Anoxic Zone (Tank No. 2)
Type Concrete tank (Tank 2)
Tank Dimensions Diam: 15.6m, height: 4.1m Working depth: 3.8m
Total Volume 783m3
Working Volume 726m3
Mixing 1 No. 11kW propeller mixer & 32kW surface aerator if required
Recycle Pump 2 No. duty /Stand by V.S.D. 150-600m3/hr pumps
Equipment D.O meter.
The anoxic zone has been designed to remove Nitrates (NO3-N) from the effluent which has been
converted from the ammonia breakdown in the aeration tank. This de-nitrification process will also
provide for better ph stabilisation. Nitrate is converted to nitrogen and oxygen. Anoxic conditions and
food source are required.
6NO3- + 5CH3OH >>>>> 5CO2 + 3N2 + 7H2O + 6OH
-
Retention Time
A retention time of 2.1 days provides adequate retention to breakdown Nitrates (NO3-N) in the
effluent.
Nitrate removal
Assuming a maximum of 1500mg/l NO3-N and a maximum flow of 340m3/ day with a specific
denitrification rate (SDNR) of 0.15g NO3-N gMLVSS/day1 I have incorporated various MLSS rates to
determine the Nitrate removal capacity of the entire system in table 4 below:
Max Flow rate Max NO3-N
Nitrate to be
removed Anoxic Volume MLSS SDNR rate
Nitrate removal
capacity
m3/day mg/l kg/day m3 mg/l
gNO3-N/g
MLSS kg/day
340 1500 510 726 5000 0.15 544.5
340 1500 510 726 5500 0.15 598.95
340 1500 510 726 6000 0.15 653.4
Table 4: Nitrate removal rates.
This designated anoxic zone provides 128% capacity to remove Nitrates from their maximum level.
1 Metcalf & Eddy. 2003. Wastewater Engineering Treatment and Reuse p.754 – 4
th Edition. Mc Graw-Hill & Farragh
Proteins
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Recycle Rate
The variable speed drive pump will allow the recycle rate to be adjusted from 10 to 20 times forward
feed at a range of flows.
Mixing
The 11kW mixer will ensure that the food, bacteria and NO3-N will be appropriately mixed to ensure
de-nitrification occurs.
Dissolved Oxygen (D.O)
A continuous D.O. meter is installed. This will permit the operator to monitor D.O.
3.7 Aeration Zone (Tanks No. 3, 9 & 1)
Type 3 No. Steel/Concrete Tanks
Tank 3 Dims Diam = 15.38m Ht = 4.1m WD = 3.8 (WV = 706m3)
Tank 9 Dims Diam = 17.66m Ht = 4.5m WD = 4.1 (WV = 1,004m3)
Tank 1 Dims Diam = 15.6m Ht = 4.1m WD = 3.8 (WV = 726m3)
Total working Volume 2,436m3
Tank 3 Aeration 45 kW Diffused Aeration System & 11kW mixer
Tank 1 Aeration 50kW Surface Aerator & 11kW mixer
Tank 9 Aeration 45kW Diffused Aeration System
F:M Ratio 0.05 - 0.1.
MLSS 5000-6000 mg/l
The effluent will gravity feed from the anoxic tank through the three aeration tanks in series (tank 3 –
tank 9 – tank 1) to breakdown BOD and Ammonia. Tank 9 will be a newly constructed tank to ensure
thorough aeration. In the event of high Ammonia influent the flexible anoxic/aeration or balancing
tank/aeration systems can also be used to provide aeration.
Retention Time
A minimum retention time of 2.5 days is required to ensure complete breakdown of BOD and
Ammonia. This provides a retention of 7.1 days.
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Dissolved Oxygen (D.O)
A diffused aeration system should be capable of producing 2.0kg O2/kW and a surface aerator should
produce 1.5kg O2/kW. The proposed combined Farragh Proteins aeration system will produce:
90 kW*2.0 kg O2/kW *24 hrs + 50 kW*1.5 kg O2/kW *24 hrs
= 6,120 kg/O2 /day.
Assuming maximum Ammonia of 1,500mg/l, BOD of 2,100mg/l at a flow rate of 340m3/day it is
expected that 3,600 kg/O2 /day will be required. As a result there is more than adequate aeration in the
system.
Feed to the Masses (F:M)
A standard F:M would be expected as follows: Feed to the bacteria =
Bacteria
Max Flow
rate BOD F
Aeration
Volume MLSS M F:M
m3/day mg/l kg/day m3 mg/l kg/day kg/day
340 2100 714 2432 5000 12160 0.059
340 2100 714 2432 5500 13376 0.053
340 2100 714 2432 6000 14592 0.049
Table 5: BOD removal rates.
This F:M is within required parameters. This can be increased if required by increasing the BOD load
or reducing the tank volume or MLSS. F:M can be reduced by increasing the MLSS in the aeration
tank. Further BOD removal will also occur in the anoxic tank.
Ammonia to the Masses (NH3:M)
It has been calculated that 1.16 gNH3/kg MLSS/hr or 40 gNH3/kgMLSS/day of ammonia is the
nitrification removal rate at the existing WWTP. During the aeration phase ammonia is converted to
Nitrite and then Nitrate. Oxygen, nitrifying bacteria and alkalinity are required for nitrification.
Conversion is a two stage process as described in the equations below:
NH4+ + 1.5O2 >>>>> NO2
- + 2H
+ + H2O (Nitrosomonas)
NO2- + 1/2O2 >>>>> NO3
- ( Nitrobacter )
Assuming a maximum of 1500mg/l NH3-N and a maximum flow of 340m3/ day with a specific
Nitrification capacity of 40gNH3-N/kgMLVSS/day I have incorporated various MLSS rates to
determine the Ammonia removal capacity of the entire system in table 6 below:
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Max Flow
rate Max NH3-N
Ammonia to be
removed
Aeration
Volume MLSS
Nitrification
rate
Ammonia
removal
capacity
m3/day mg/l kg/day m3 mg/l
gNH3-N/kg
MLSS kg/day
340 1500 510 2432 5000 40 486.4
340 1500 510 2432 5500 40 535.04
340 1500 510 2432 6000 40 583.68
Table 6: Nitrification capacity.
This designated aeration system provides 114% excess capacity to remove Ammonia from their
maximum level.
Internal Equipment
A continuous D.O. meter will be installed. The D.O. meter will control the variable speed drive
aerators to keep D.O. between 2-3mg/l.
3.8 Chemical Precipitation
Chemical Ferric Sulphate (Fe2 SO4)
Dose Pump Rating 1 no. dosing pump (1-10 l/hr)
Ferric Sulphate will be dosed into the effluent as it leaves the aeration tank at an appropriate rate. .
This will allow the chemical to mix with the effluent before entering the clarifier. The chemical will
cause the phosphorous in the effluent to settle to the bottom of the Clarifier and be removed as return
sludge.
3.9 Clarifier
Tank Steel tank
Tank Dimensions Diam = 9.5m Ht = 2.8m sidewall depth
Working depth 2.6m
Surface Area 70.8m2
Total Volume 184m3
RAS & WAS pumps (Ph 2) 2 No. 0-60m3
/hr
Upward Flow
The maximum upward flow recommended in a Clarifier should be 0.5m/hr – 1m/hr. However in meat
abattoirs and rendering facilities I have found that a maximum upward flow of 0.5m/hr is ideal.
Assuming 0.5m/hr as the maximum upward flow the Clarifier is capable of handling 35m3/hr. The
upward flow at 15m3/hr will be 0.21m/hr, which is ideal.
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Solids Loading
The sludge feed to the clarifier will be the forward feed + the return activated sludge rate (RAS). This
will allow a maximum sludge feed of 37.5m3 (15+22.5). The solids loading is a measure of the
quantity of sludge solids (kg) applied to the surface area of the clarifier (m2). The optimum solids
loading may vary but should be within 0.25 to 6 kg/m2/hr. The estimated solids loading to the clarifier
can be calculated as follows:
MLSS mg/l x (Forward Feed + RAS)(m3/hr) = 6000 x 37.5
1000 x Clarifier surface area (m2) 1000 x 70.8
= 3.21kg/m2/hr
Retention
An ideal retention time for the forward feed and RAS in a clarifier is 2.5 - 4 hrs retention. Excessive
retention time can cause sludge to rise. However the removal of Nitrates in the anoxic zone will help
settlement to occur. Good sludge settlement, stabilised denitrified sludge and an increased RAS should
overcome this. Some clarifiers have retention times up to 8.5 hrs without any sludge rising issues. The
retention time at 15m3/hr will be 4.9 hrs, which is slightly high but should be OK as there is a greater
retention time at the existing facility.
3.10 Sludge Tank
Tank Steel tank
Tank Dimensions Diam = 3m, Ht = 4.0m
Total Volume 28m3
The sludge tank stores and settles waste sludge prior to dewatering. Assuming a maximum of 85m3 of
sludge will be produced per day, the tank has a capacity for 8 hrs sludge.
3.11 Dewatering Decanter
Decanter Capacity 10m3/hr
Internal Equipment Chemical Coagulation unit
Assuming that 25% of effluent will require to be dewatered depending on the thickness of the WAS
then the plant will need to be capable of dewatering 85m3/day. A decanter with a capacity of 10m
3/hr
will be operated for a maximum of 8.5 hrs/day. The centrate from the decanter will be transferred
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directly to the anoxic zone or balancing tank. The sludge will be dropped or augered into an adjacent
skip.
3.12 Sand filter
Filter Capacity 20m3/hr
The existing sand filter has the capacity for the extra effluent. The centrate from the clarifier gravity
feeds to a buffer tank, which is then pumped into the final tank 6 and through the sand filter to remove
fine solids. The sand filter will be back washed as required.
3.13 Discharged treated Water
The final treated water will pass through a composite sampler and pH meter before being gravity fed
to the River Erne.
4. Monitoring and Analysis The monitoring of a waste water treatment plant is essential to ensure it is operated correctly. The
WWTP operator will daily record parameters such as D.O., pH, flows, tank levels, Cone Test, MLSS,
SVI to ensure the WWTP is operated in accordance to its design parameters.
Daily and or weekly/monthly samples will be taken and analysed to monitor incoming effluent and
discharge COD, SS, pH, NH3-N, NO3-N, FOG’s, BOD & P etc in accordance with IPPC license
ELVs. The existing laboratory will carry out most of this analysis and contains the following
equipment:
o Spectrophotometer
o COD Digester
o Oven
o Balance scales
o Imhoff Cones
o Microscope
o Laboratory equipment (jars, bottles etc.)
o Pipettes & other ancillary items
o Hot water & washing facilities
5. Management, Operation & Training A manual specifying detailed operational procedures and laboratory analysis of the WWTP will be
compiled. The environmental manager and WWTP operator will be trained into operating the WWTP
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in accordance with the manual. The daily records will be recorded by the WWTP operator and
reviewed and signed by the environmental manager daily.
6. Maintenance A preventative maintenance schedule and spares list will be documented and included on the
maintenance system.
7. Conclusion The existing Farragh Proteins WWTP is capable of treating the current volume of effluent in
accordance with their IPPC license ELV’s. The existing screen, DAF, anoxic zone, 2 No. Aeration
tanks, clarifier and sludge dewatering systems together with the proposed construction of two new
1004m3 tanks as a balancing tank and aeration tank ensures that there is adequate capacity to treat the
proposed increase in production wastewater.
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