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WASTEWATER REUSE CRITERIA IN GREECE
A. Andreadakis, E. Gavalaki, D. Mamais, A. Tzimas
National Technical University of Athens, Faculty of Civil EngineeringDepartment of Water Resources, Hydraulic and Maritime Engineering
5, Iroon Polytechniou, Zografou, Athens 15780, Greece
WASTEWATER REUSE POSSIBILITIES
Wastewater reuse for non-potable purposes
• Agricultural• Urban• Industrial• Recreational • Groundwater recharge (to aquifers not used for potable purposes)
Wastewater potable reuse
• Indirect (including groundwater recharge to aquifers used for potable purposes)• Direct
Water Shortage
Group I Group II No legal obligation for
secondary wastewatertreatment
Severe scarcity offunds
Severe water shortage Agricultural reuse High risk acceptability
Pay as little as possiblein view of soundepidemiologicalevidence
Legal obligation forsecondary wastewatertreatment
More funds available
Shortage usually local Diversity in reuse Reluctance to accept
even small risk Willingness to pay
more in order toaddress eventheoretical risks
Adequacy of Water Supply
Group III
• North Europe and several industrialised countries
• Most of the EU
• Reuse is envisaged as an interesting concept in the context of sustainability but in practical terms often only industrial reuse (usually in plant) is considered in practice
SIGNIFICANCE OF WASTEWATER REUSE
GENERAL REUSE STANDARDS
Group I
• For unrestricted irrigation no standards and very limited if any treatment requirement
• For unrestricted irrigation and other urban and recreational reuse usually the WHO standards are adopted
– 200-1000 FC/100ml
Group II
• For unrestricted irrigation usually secondary treatment is required with or without disinfection
• For unrestricted irrigation and other urban and recreational reuse tertiary treatment followed by disinfection is adopted
– 2-50 FC or TC/100 ml
Drinking and food
preparation4%
Toilet flushing
32%
Personal hygene
35%
Laundry18%
Other uses11%
DOMESTIC REUSE
Possibility for reuse of grey or rain water
60%
Potable water quality40%
DOMESTIC REUSE
Domestic and commercial consumption
78%
Industrial consumption
12%
Public urban consumption
10%
URBAN REUSE (potential for Athens)
Recommended Guidelines for microbiological and conventional parameters for agricultural wastewater reuse in Greece
Fecal
coliforms/100 mlBOD5
(mg/l)SS
(mg/l)
Turbidity(NTU)
Recommended treatment
Restricted Irrigation Forests and areas where access to the public is not expected, fodder, industrial crops, pastures, trees (including fruit bearing trees on the condition that during collection the fruits do not come into contact with the ground), seed crops, crops that produce products which are processed before consumption. Spray irrigation should not be practiced.
200 as median value
800 for 95% of samples
25 for 95% of samples
35 for 95% of samples
secondary biological treatment a disinfection b
Unrestricted Irrigation All other crops such as vegetables, vineyards, crops with products which are consumed raw, greenhouses. Unrestricted irrigation allows for different irrigation methods including spray irrigation.
5 for 80% of samples
15 for 95% of samples
100 max value
10 for 80% of samples
10 for 80% of samples
2 median value
secondary biological treatment a tertiary treatment c
disinfection b
a. Recommended methods for secondary treatment include various types of activated sludge process, biological filters and rotating biological contactors. Other systems including natural systems and on site systems producing effluents of equivalent quality (BOD/SS = 25/35) can be accepted on the basis of adequate documentation. With respect to nitrogen concentrations in the effluent must be lower than 30 mg/l except in cases of long term surface storage, where a concentration of 15 mg/l for nitrogen and 4 mg/l for phosphorus must be adopted.b. Chlorination, ozonation, or other chemical disinfectants, UV radiation, membrane processes.c. Normally coagulation, flocculation, sedimentation, filtration. Direct or contact filtration can be used if secondary treatment produces effluent with SS concentrations lower than 20 mg/l for 80% of the samples.
Recommended Guidelines for microbiological and conventional parameters for urban non-potable reuse, habitat restoration, recreation in Greece
Fecal
coliforms/100 mlBOD5
(mg/l)SS
(mg/l)
Turbidity(NTU)
Recommended treatment
Landscape areas (cemeteries, freeway landscaping, golf courses, parks), landscape and recreational impoundments, fire fighting, soil compaction, dust control, cleaning roads, sidewalks, toilet and urinal flushing, decorative fountains.
5 for 80% of samples
15 for 95% of samples
100 max value
10 for 80% of samples
10 for 80% of samples
2 median value
secondary biological treatment a tertiary treatment b
disinfection c
a. Recommended methods for secondary treatment include various types of activated sludge process, biological filters and rotating biological contactors. Other systems including natural systems and on site systems producing effluents of equivalent quality (BOD/SS = 25/35) can be accepted on the basis of adequate documentation. With respect to nitrogen concentrations in the effluent must be lower than 30 mg/l except in cases of long term surface storage, where a concentration of 15 mg/l for nitrogen and 4 mg/l for phosphorus must be adopted.b. Normally coagulation, flocculation, sedimentation, filtration. Direct or contact filtration can be used if secondary treatment produces effluent with SS concentrations lower than 20 mg/l for 80% of the samples.c. Chlorination, ozonation, or other chemical disinfectants, UV radiation, membrane processes.
Recommended Guidelines for microbiological and conventional parameters for industrial reuse in Greece
Fecal coliforms/100 ml
BOD5
(mg/l)SS
(mg/l)Turbidity
(NTU)
Minimum recommended
treatment a
Once through cooling waters 200 as median value
800 for 95% of samples
25 for 95% of samples
35 for 95% of samples
secondary biological treatment b disinfection c
Recirculated cooling systems, boiler and process waters
5 for 80% of samples
15 for 95% of samples
100 max value
10 for 80% of samples
10 for 80% of samples
2 median value
secondary biological treatment b tertiary treatment d
disinfection c
a. Additional treatment may be needed depending on the specific requirements of each application.b. Recommended methods for secondary treatment include various types of activated sludge process, biological filters and rotating biological contactors. Other systems including natural systems and on site systems producing effluents of equivalent quality (BOD/SS = 25/35) can be accepted on the basis of adequate documentation. With respect to nitrogen concentrations in the effluent must be lower than 30 mg/l except in cases of long term surface storage, where a concentration of 15 mg/l for nitrogen and 4 mg/l for phosphorus must be adopted.c. Chlorination, ozonation, or other chemical disinfectants, UV radiation, membrane processes.d. Normally coagulation, flocculation, sedimentation, filtration. Direct or contact filtration can be used if secondary treatment produces effluent with SS concentrations lower than 20 mg/l for 80% of the samples.
N=NO e-k D + a SS
F(N)=F(NO) e-F(k) D + F(a) F(SS)
Frequency Chart
(FC/100ml)
.000
.009
.019
.028
.037
0
46.25
92.5
138.7
185
0.00 68,750,000.00 137,500,000.00 206,250,000.00 275,000,000.00
5,000 Trials 104 Outliers
Forecast: No
0.00 83,748,309.24 167,496,618.48251,244,927.72334,993,236.96
No
Frequency Chart
FC/100ml
.000
.009
.018
.027
.036
0
44.75
89.5
134.2
179
0.00 1,375,000.00 2,750,000.00 4,125,000.00 5,500,000.00
5,000 Trials 122 Outliers
Forecast: No SECONDARY
0.00 1,780,144.98 3,560,289.96 5,340,434.95 7,120,579.93
No secondary
Frequency Chart
.000
.007
.015
.022
.030
0
37.25
74.5
111.7
149
10.00 16.00 20.00 27.50 35.00
5,000 Trials 52 Outliers
Forecast: TSS
5.84 12.93 18.81 25.69 32.57
TSS
F(N) F(NO) e-F(k)
D
F(N) F(a) F(SS)
F(N)=F(NO) e-F(k) D + F(a) F(SS)
Frequency Chart
K
.000
.007
.014
.020
.027
0
33.75
67.5
101.2
135
0.05 0.11 0.18 0.24 0.30
5,000 Trials 20 Outliers
Forecast: K(D<60)TERTIARY
0.04 0.10 0.17 0.23 0.29
K
Frequency Chart
.000
.022
.044
.066
.088
0
110.2
220.5
330.7
441
0.00 37.50 75.00 112.50 150.00
5,000 Trials 98 Outliers
Forecast: α-value (D>80)
0.29 112.08 223.87 335.65 447.44
α-value
UV DISINFECTION RESULTS ON SECONDARY EFFLUENT COMPLYING TO 35 mg/l SS FOR 95% OF SAMPLES FOR DIFFERENT DOSES D (mWs/cm2)
1
10
100
1000
10000
100000
1000000
0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
% TIME
FC/1
00 m
l
D=10 D=30 D=40 D=60 D=75 D=90 D=120 D=150
UV DISINFECTION RESULTS ON SECONDARY EFFLUENT GREATER THAN 60 mg/l SS FOR 95% OF SAMPLES FOR DIFFERENT DOSES D (mWs/cm2)
1
10
100
1000
10000
100000
1000000
0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
% TIME
FC/1
00 m
l
D=10 D=30 D=40 D=60 D=75 D=90 D=120 D=150
UV DISINFECTION RESULTS ON TERTIARY EFFLUENT COMPLYING TO 5 mg/l SS FOR 80% OF SAMPLES FOR DIFFERENT DOSES D (mWs/cm2)
1
10
100
1000
10000
100000
0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
% TIME
FC/1
00 m
l
D=10 D=30 D=40 D=60 D=75 D=90 D=120 D=150
Agronomic Guidelines of water quality for irrigation
Degree of restriction on usePotential irrigation problem Units
None Slight to moderate Severe
SalinityECw
1 dS/m < 0.7 0.7 - 3.0 > 3.0orTDS mg/l < 450 450 - 2000 > 2000
InfiltrationSAR2 = 0 - 3 and ECw > 0.7 0.7 - 0.2 < 0.2
3 - 6 > 1.2 1.2 - 0.3 < 0.3 6 -12 > 1.9 1.9 - 0.5 < 0.512-20 > 2.9 2.9 - 1.3 < 1.320-40 > 5.0 5.0 - 2.9 < 2.9
Specific ion toxicitySodium (Na)Surface irrigation SAR < 3 3 - 9 > 9Sprinkler irrigation mg/l < 70 > 70Chloride (Cl)Surface irrigation mg/l < 140 140 - 350 > 350Sprinkler irrigation mg/l < 100 > 100Boron (B) mg/l < 0.7 0.7 - 3.0 > 3.0
Miscellaneous effectsNitrogen (NO3-N)3 mg/l < 5 5 - 30 > 30Bicarbonate (HCO3) mg/l < 90 90-500 > 500pH Normal range 6.5 – 8.0Residual Cl (sprinklerirrigation)
< 1 1-5 > 51 ECw means electrical conductivity in deciSiemens per metre at 25°C2 SAR means sodium adsorption ratio3 NO3-N means nitrate nitrogen reported in terms of elemental nitrogen
Maximum recommended permissible levels of trace elements in reclaimed wastewater
Trace ElementMax concentration (μg/l)
• Al (aluminium) 5000• As (arsenic) 100• Be (beryllium) 100• Cd (cadmium) 10• Co (cobalt) 50• Cr (chromium) 100• Cu (copper) 200• F (fluoride) 1000• Fe (iron) 5000• Li (lithium) 2500
Trace ElementMax concentration (μg/l)
• Mn (manganese) 200• Mo (molybdenum) 10• Ni (nickel) 200• Pb (lead) 5000• Se (selenium) 20• V (vanadium) 100• Zn (zinc) 2000• Hg (mercury) 5