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