Reality of residential wastewater organic and hydraulic loads - PowerPoint PPT Presentation

Reality of residential wastewater organic and hydraulic loads Consequences with respect to testing small WWTP for CE marking Dr. Anne CAUCHI Technical Department VEOLIA WATER Anne CAUCHI Expert Eaux Usées et Boues 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Stake � Be sure having SWWTP suited to real organic and hydraulic loads � Question 1: are organic and hydraulic loads for individual house well-known? � Standard EN 12566-3+A1 fix the daily volume per inhabitant and the range of concentration of this volume : Daily volume (L/ inh.) 150 BOD 5 concentration (mg O 2 /L) 150 to 500 � Solution : measurements � Question 2 : what are the best design values? � Solution : propositions witch have to be discussed 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

waste water from individual houses: how to sample ? � Punctual sampling ? NO (totally random) � Proportional sampling ? NO (not rather precise) � Sampling from total daily volume : YES The best way to obtain 24h average sample 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Application � equipment is gathered in a mobile unit 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012 4 - Présentation électronique

First waste water collecting tank � each site is equipped with a 200L buried tank upstream to the purification plan � In this tank, all the waste water from the house is rejected (moving T-square) 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012 5 - Présentation électronique

Application � a 1m3 storage tank is installed near the collecting tank � A pump is placed in the collecting tank to transfer waste water into the storage, as soon as they are produced 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012 6 - Présentation électronique

End of the daily collect : pumping the residual volume � After 24h, the residual volume of water witch is still at the bottom of the tank is aspired � There Is no more waste water in the collecting tank (can be 20% of the total pollution). 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012 7 - Présentation électronique

Measurement of the daily volume � horizontality is verified, height can be read 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012 8 - Présentation électronique

The 24h sampling can be done � Total volume collected is well mixed between each elementary samples, to realise finally the 24h sample � Analysis are made in accredited laboratory � Parameters : SS, COD, BOD5, NTK, NH4, NO2, NO3, Pt 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012 9 - Présentation électronique

Results � 138 “24h” samples � for 7 days running minimum each house � Some for 14 days, one for 21 days � Occupiers : Permanent home Active and retired persons With or without children/baby From 2 to 8 persons Different standing 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Distribution of daily volumes per inhabitant Descriptive statistics of 1 accumulated frequency the daily volume (L/inh) Samples 138 0.8 Average 86 Minimum 16 0.6 maximum 244 10% 45 0.4 90% 135 � one inhabitant uses less 0.2 than 90 litres by day Daily volume L/inh.d � Reasonable bounds values are 45 � � � � 135 L/inh.d 0 0 50 100 150 200 250 � average between those bounds : 81 L/inh.d 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

BOD 5 Concentrations in daily volumes 1 accumulated frequency Descriptive statistics of the daily BOD 5 0.9 concentration (mgO 2 /L) 0.8 Samples 138 0.7 Average 667 0.6 Minimum 120 maximum 3380 0.5 10% 268 0.4 90% 1230 0.3 � Concentration of BOD 5 is 0.2 higher than 650 mg O 2 /L 0.1 � Reasonable bounds values BOD 5 of daily sample (mg O 2 /L) are 270 � 1230 mg O 2 /L 0 � Average between those 0 500 1000 1500 2000 2500 3000 3500 bounds : 600 mg O 2 /L 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Comparison with BOD 5 Concentrations from European notified laboratory BOD 5 Influent from 8 notified laboratories 100% 90% 80% urban network 70% Average : 296 mg O 2 /L 60% network from a block of flats 50% Average : 445 mg O 2 /L 40% 30% urban network produce influent with 20% a diluted BOD 5 concentration 10% mg O2/L 0% 0 100 200 300 400 500 600 700 800 900 1000 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

At the beginning, the same organic load to be treated Individual house V< 90L/inh.d BOD 5 > 600 mg O 2 /L A SWWTP has to treat concentrated influent Urban network How to take this V > 150 L/EH.d into account ? BOD 5 < 300 mg O 2 /L BY-PASS SWWTP is tested with diluted influent 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Days after days : not the same loads 300 Daily hydraulic load (L/inh) 250 200 150 100 50 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 200 Daily Organic load (g BOD 5 /L) 180 160 140 120 100 80 60 40 20 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Relation between volume and BOD 5 concentration? � High volume is not necessary 300 Daily volume(L) vs BOD 5 (mgO 2 /L) associated to low concentration 250 � Low volume is not necessary associated to high concentration 200 Daily volume Illustration : regression graph 150 100 50 DBO5 � Its necessary to detail the 0 0 1000 2000 3000 4000 composition of the daily sample � Water use is precisely take down during each 24h collection 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

Split up a daily pollution � The pollution of one inhabitant can be break up into following principal components parts : Theoretical Total inhabitant pollution - bathroom (shower…) -Kitchen (preparation of meals, dishes) showers WC washings dishes meals other -Toilets (human excreta) -Laundry (washes) -Other activities � Each components is not “full” each day : examples washings showers WC dishes meals other Inhabitant pollution - day « X » washings showers WC dishes meals other Inhabitant pollution - day « Y » 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012

First data to think about � What could be the best choice for design rules : weekly average rather than daily ? Hydraulic load Organic load Weekly average (L/inh.d) (g BOD 5 /inh.d) Average 88 54 Min � Max 50 � 160 16 � 140 min/max 3.2 8.6 10% � 90% 51 � 125 21 � 90 90%/10% 2.5 4.3 16 th International EWA Symposium “Sustainable Wastewater Management – New solutions for new problems” Munich, Germany, 8-9 May 2012