Ecological engineering Ecotechnology. Soil for groundwater protection and wastewater treatment. Rainwater harvesting

Transcription

1 THT 281/06 Soil for groundwater protection and wastewater treatment Petter D. Jenssen Department of Mathematical Sciences and Technology Norwegian University of Life Sciences Ecological engineering Ecotechnology The development of human society with nature for the benefit of both. (Mitsch and Jørgensen 1989) (Eritrea) The water cycle Rainwater harvesting Foto: Kjell Esser, Noragric Rainwater Harvesting: Surface collection of water and infiltration/storage Rainwater Harvesting: Surface collection of water and infiltration/groundwater recharge Water collection area Water infiltration /storage The Agricultural University of Norway The Agricultural University of Norway 1

2 Rainwater Harvesting: Surface collection of water and infiltration/groundwater recharge Constructed wetland flow direction/purification The Agricultural University of Norway The Agricultural University of Norway High quality effluent Constructed wetland at Dal primary school Rainwater Harvesting: Surface collection of water and groundwater recharge Average influent (STE) and efluent concentrations (mg/l) Parameter Influent Effluent Total - P 2,9 0,2 Total - N 29,0 12,0 COD SS < 5 T. coli. /100ml < 2 Kabul 2002 Foto: H.P. Mangx Uncontrolled/random infiltration Pathogens NO 3 Foto: H.P. Mang Groundwater 2

3 Decentralized solution? Decentralized solution? Local recycling? Controlled infiltration Foto: H.P. Mang Controlled infiltration Foto: H.P. Mang Groundwater Groundwater Composted faecal matter Kabul 2002 Greywater and urine Faecal matter Foto: H.P. Mang Foto: H.P. Mang Pathogens Foto: H.P. Mangx Uncontrolled/random infiltration Foto: H.P. Mangx Uncontrolled/random infiltration NO 3 NO 3 Groundwater Groundwater 3

4 Decentralized solution? Local recycling? Foto: H.P. Mangx Uncontrolled/random infiltration Controlled infiltration Foto: H.P. Mang Groundwater Groundwater Infiltration systems Open systems - infiltration in ponds Setermoen rapid infiltration system Subsurface (buried) systems - infiltration trenches Illustrations: Jenssen and Siegrist 1991 Photos: P.D. Jenssen Open rapid inf. Dam, 69 o north Design capacity 5000 persons Rapid infiltration 100 Treatment results Rapid infiltration Bardu Lesja 20 0 Organisk stoff Fosfor Nitrogen (Kraft 1998) Foto: P.D. Jenssen 4

5 Infiltration systems - treatment performance* BOD SS Total N Total P Rapid infiltration 90 >90 (30) - 80 > 95 Buried (slow) infiltration Groundwater level Indicator bacteria** <10-3 * See Jenssen and Siegrist 1990 for more details ** Effluent concentration Buried soil infiltration system Large buried infiltration system Pretreatment/septic tank Infiltration unit Photo: K. Robertsen Infiltration trench Mound system under construction Photo: P.D. PDJ Jenssen

6 A mound system Sandfilter Peilerør PDJ 1999 Sandfilter Water level control pipe Buried infiltration systems pollutants of concern; combined wastewater Sand Distribution pipe Soil Wastewater source Pretreatment Effluent delivery Organic matter P NO 3 Bacteria Virus? Infiltration area Clogging zone Percolation GW recharge Ground water Bottom drain PDJ 99 Jenssen1999 (Siegrist et al. 2000) Water treatment by filtration through sand Treatment efficiency Mounds and small infiltration systems Infiltrasjon Jordhaug 20 0 Org. materiale Fosfor Nitrogen (Køhler 1998) 6

7 Infiltration systems - treatment performance* BOD SS Rapid infiltration 90 >90 Buried (slow) infiltration >90 >90 Reduction of organic matter biofilm media in activated sludge conventional systems K1 K2 Natrix O Total N Total P (30) - 80 > (80) 100 Indicator bacteria** <10-3 <10-3 * See Jenssen and Siegrist 1990 for more details ** Effluent concentration d= 9 mm d= 15 mm d= 60 mm Biofilm media surface area m 2 /m 3 Kaldnes TM Reduction of organic matter Expanded clay aggregates (FiltraliteHC TM ) as biofilm carrier Reduction of organic matter Porous media as biofilm carrier Filtralite Sand Particle size 2-5mm Particle size 2-5mm Particle size mm Surface area Bacteria on Filtralite > 5000m 2 /m 3 surface Surface area > 5000m 2 /m Surface area >> 5000m 2 /m Phosphorus removal in soils depth of infiltration trenches Phosphorus removal in soils Organic layer, O horizon Oxidized layer, B horizon Subsoil, C horizon Organic layer, O horizon Oxidized layer, B horizon Subsoil, C horizon 7

8 Phosphorus removal in soils Phosphorus forms in soil dependent on ph Fe 3 (PO 4 ) 2 AlPO 4 Brady Ca 3 (PO 4 ) 2 Small buried infiltration systems Soil Wastewater source Pretreatment Effluent delivery Infiltration area Clogging zone Percolation Infiltration systems bacteria removal Soil surface Depth cm Infiltration trench Bacteria/100ml or 100g of soil E coli Total coli Total bacteria GW recharge Ground water (Siegrist et al. 2000) Cloggede zone (McCoy and Ziebell 1975) Background levels 30 cm below the trench Infiltration systems bacteria removal Clogged zone The fate of microorganisms in soil Soil surface Depth cm Infiltration trench Bacteria/100ml or 100g of soil E coli Total coli Total bacteria Cloggede zone (McCoy and Ziebell 1975) 8

9 The fate of microorganisms in soil Size of soil pores vs. size of microorganisms The fate of microorganisms in soil The fate of microorganisms in soil The fate of microorganisms in soil Rapid infiltration Open rapid inf. Dam, 69 o north Setermoen 5000 pe Foto: P.D. Jenssen 9

10 Treatment results Rapid infiltration - phosphorus Bardu Lesja 20 0 Organisk stoff Fosfor Nitrogen (Kraft 1998) Groundwater level Treatment results Rapid infiltration - nitrogen Nitrogen transformations in soils Bardu Lesja 20 0 Organisk stoff Fosfor Nitrogen (Kraft 1998) (Lance 1978) Rapid infiltration Loading rate assessment Wastewater infiltration system Anaerobic zones Natural groundwater level Groundwater level with infiltration Critical cross-section Oksidized zone Photo: P.D. Jenssen 1. Hydraulic capacity 2. Infiltration rate 3. Purification ability 10

11 Site investigations Office preparations Topographic maps Soil or geological maps Groundwater interests/wells Hand auger Site investigations Surface observations Vegetation type Land formations Soil observations from roadsides/or other open surfaces Groundwater observations from wells/vegetation Site investigations Site investigations Hand auger Subface observations Hand auger Motor hammer Backhoe Hand auger Subface observations Hand auger Motor hammer Backhoe Site investigations The use of a motor-hammer Site investigations - the use of a motor hammer * Indirect assessment of vertical texture profiles 11

12 Site investigations Excavations - the use of a backhoe Hydraulic capacity Wastewater infiltration system Impermeable Groundwater level with infiltration Natural groundwater level Q = K* M*L*i Q= Hydraulic capacity (m3/d) K = Hydraulic conductivity (m/d) M = Acceptable rize in groundwater level (m) L = Length of the infiltration trench (m) i = The slope of the groundwater surface (h/l) Manual infiltrometer Electronic infiltrometer Loading rate assessment Wastewater infiltration system Natural groundwater level Groundwater level with infiltration Critical cross-section 1. Hydraulic capacity 2. Infiltration rate 3. Purification ability Infiltration rate for wastewater How much water can be infiltrated per unit area? Clean water Infiltration rate Wastewater 12

13 Infiltration systems - loading rates Grain size distribution Sorting (So) and mean grain size(md) Open systems - infiltration in ponds cm/d Subsurface (buried) systems - infiltration trenches QuickTime og en Photo - JPEG-dekomprimerer kreves for å se dette bildet. d 10 = d 50 = 0.33 d 60 = 0.59 So (d 60/ d 10 ) = 9.37 Illustrations: Jenssen and Siegrist 1991 Photos: P.D. Jenssen 1-5 cm/d d 10 = d 50 = 0.33 d 60 = 0.59 Loading rate assessment diagram Md/So (Meso) diagram Loading rate assessment diagram Md/So (Meso) diagram Sorting ( d 60 /d 10 ) Sorting ( d 60 /d 10 ) K (m/d) 1,3 L.R. (cm/d) 2-2, > ,0 4,0 Mean grain size (d 50 ) (Jenssen & Siegrist 1991) Mean grain size (d 50 ) Design of wastewater infiltration systems Wastewater infiltration system Natural groundwater level Groundwater level with infiltration Darcy s law: q=k*i Q = K* M*L*i q = Q/(M*L) = K*i Q= Hydraulic capacity (m3/d) q = Darcy flow (m/d) K = Hydraulic conductivity (m/d) M = Acceptable rize in groundwater level (m) L = Length of the infiltration trench (m) i = The slope of the groundwater surface (h/l) Wastewater infiltration system 1. Hydraulic capacity 2. Infiltration rate 3. Purification ability Impermeable Groundwater level with infiltration Natural groundwater level 13

14 Average velocity in the soil pores (v) Average flow velocity (v) Impermeable Wastewater infiltration system Groundwater level with infiltration Natural groundwater level Darcy s law: q=k* i v = q/n e v = average flow velocity in the soil pores (m/d) n e = available porosity (dimensionless) q=k*i, q = Darcy flow (m/d) K = Hydraulic conductivity (m/d) i = The slope of the groundwater surface (h/l) v=q/n e v = average velocity in the soil pores (m/d) n e = porosity available for flow (0-1,0) Clay Gravel Stones Main references Jenssen P.D., Design criteria for wastewater infiltration systems. Presented at the international conference: "Alternative waste treatment systems". IAWPRC, New Zealand, May 26-27, In: Bhamidimarri R. (ed.), "Alternative waste treatment systems", Elsevier, London, pp: Jenssen P.D. and R.L. Siegrist, Technology assessment of wastewater treatment by soil infiltration systems. Wat. Sci. Tech. 22/(3/4). pp Jenssen P.D. and R.L. Siegrist, Integrated Loading Rate Determinations for Wastewater Infiltration Systems Sizing. Proc. Sixth National Symposium on Individual and Small Community Sewage systems, Chicago, ASAE Publ.10-91, pp Siegrist, R.L., Tyler, E.J., Jenssen, P.D Design and peformance of onsite wastwater soil absorption systems. Paper presented at National Research Needs Conference Risk-Based Decision Making for Onsite Wastewater Treatment, St. Louis, Missouri, May USEPA, Electic Power Research Inst. Community Env. Center, National Decentralized Water Resources Capacity Development Project. Jenssen P.D., Jonasson S., og Heistad A Naturbasert rensing av avløpsvann - en kunnskapssammenstilling med hovedvekt på norske erfaringer. VA-forsk Rapport. In print. 14