Harnessing non-conventional water Urban wastewater

Transcription

1 International Seminar on Olive Growing and the Environment Harnessing non-conventional water Urban wastewater Guy Levy Agric. Res. Org. (ARO) The Volcani Center Bet Dagan Israel Aerial photo of the Dan region effluent treatment plant 1 1

2 TWW differ from their water of origin by: Higher concentration of nutrients (N,P, K). Higher concentration of Boron Presence of pathogenic microorganisms (e.g., viruses, bacteria, protozoa) Higher total salinity and concentration of electrolytes that could lead to specific toxicity (Na, Cl, B, HCO 3 ). Higher sodium adsorption ratio (SAR). Higher organic load (dissolved organic matter (DOM) and total suspended solids (TSS). 2 2

3 Table 1. Chemical characteristics of secondary treated waste water (TWW) and fresh water (FW) used for irrigation in the Bet She an Valley, Israel. Average values for four years ( ). Water quality parameter TWW Irrigation water FW SAR 5.1 (0.95) 3.1 (0.37) EC (ds m -1 ) 1.9 (0.23) 1.2 (0.10) ph 7.6 (0.27) 7.6 (0.32) N-NH 4+ (mg L -1 ) 35.1 (11.0) 0.0 (0.00) N-NO 3- (mg L -1 ) 0.14 (0.24) 0.06 (0.12) P (mg L -1 ) 2.3 (3.23) 0.00 (0.00) K (meq L -1 ) 0.97 (0.05) 0.32 (0.26) Ca + Mg (meq L -1 ) 6.8 (0.83) 5.9 (0.70) Na (meq L -1 ) 8.7 (1.44) 5.4 (0.29) Cl (mg L -1 ) (24.7) (28.01) B (mg L -1 ) 0.28 (0.06) 0.10 (0.005) TSS (mg L -1 ) (69.8) 0.0 (0.00) BOD (mg L -1 ) 86.8 (52.7) 0.0 (0.00) COD (37.1) 0.0 (0.00) 3 3

4 Why are we concerned by the higher levels of sodicity (SAR) and organic matter load in TWW? 4 4

5 Irrigation with TWW Potential risks associated with higher SAR and organic load Presence of suspended solids 100 Loess Can lead to physical blocking of water conducting pores during the irrigation Relative hydraulic conductivity (%) High quality TWW (DOC 54 mg L -1 ) Low quality TWW (DOC 313 mg L -1 ) Pore volume (V/Vo) 0.02 N 5 5

6 Irrigation with TWW Potential risks associated with higher SAR and organic load Higher SAR and dissolved organic matter (DOM) (i) Enhances clay dispersion and aggregates destabilization. Stability ratio Fresh water (ESP ~1.5) TWW (ESP ~5) TWW (ESP~8) Clay content (%) 6 6

7 Irrigation with TWW Potential risks associated with higher SAR and organic load Higher SAR and dissolved organic matter (DOM) (ii) May cause a deterioration in soil permeability to water and to increased levels of runoff and soil erosion. Total soil loss (g m -2 ) Irrigation treatment Sandy soil Prewetting treatment Clay soil Dry Prewett ed Dry Prewetted Fresh water TWW (From Levy 28.1 et al., 2005)

8 Irrigation with TWW Potential risks associated with higher SAR and organic load Presence of dissolved organic matter (DOM) (iii) May cause the development of hydrophobic conditions (i.e. water repellency) at dry soil surfaces. FW (From Levy et al., 2005) (Tarchitzky et al., 2007; EJSS 58: ) TWW 8 8

9 Concluding comments Irrigation with TWW may have some positive effects, mainly being a source for key nutrients. The higher salinity of TWW may require changing of common irrigation practices. Effects of irrigation with TWW on important soil physical properties are inconsistent and depend on: (i) soil properties, & (ii) conditions prevailing in the field. Cont./ 9 9

10 Concluding comments (cont.) There is a constant improvement in the quality of the treatments that raw effluents are being subjected to, thus yielding TWW of better quality. Our soils are a valuable resource. Irrigation with TWW should, therefore, be accompanied by close monitoring of different soil properties in order to maintain the soils in a satisfactory state for continued productive use by future generations

11 Thank you for your attention 11 11

12 Thank you for your attention 12 12

13 The importance of soil structural stability is reflected by its impact, amongst others, on: Air to water ratio (aeration). C cycle. Availability of nutrients. Ability of the soil to absorb, hold and transmit water. Soil susceptibility to processes controlling seal formation, runoff and soil loss

14 Processes that may affect soil structural stability: Clay swelling and dispersion. Clay movement down the soil profile. Aggregate breakdown as a result of: (i) slaking. (ii) impact of water drops of high kinetic energy. Cont / 14 14

15 In what ways could irrigation with TWW lead to soil degradation? Irrigation with TWW could enhance the previously mentioned phenomena that adversely affect soil structure because of: (i) Its higher SAR. (ii) Its higher organic load: - dissolved organic carbon

16 Concluding comments (cont.) 4. It is very difficult and extremely costly to reclaim and amend soils whose structure and stability have been severely degraded. Consequently, caution should be exercised, and soils that are subjected to irrigation with TWW should be closely monitored with respect to possible degradation of their structure, so that it is ensured that our soils are passed on to future generations in a good shape

17 Effects of DOM on Na-clay behavior (From: Tarchitzky et al. 1999, SSSAJ 63: ) FV (meq/l) DOC (ppm) 17 17

18 Does irrigation with TWW pause a danger to soil structural stability? Irrigation with TWW could enhance the previously mentioned phenomena that adversely affect soil structure because of: (i) Its higher SAR. (ii) Its higher organic load: - dissolved organic carbon. - total suspended solids. (iii) Its possible effects on changes in the properties and quantity of soil organic matter

19 Indicators used to determine changes in soil structural stability: 1. Clay depletion from the upper soil layer (clay dispersion). 2. Aggregate stability (slaking). 3. Saturated hydraulic conductivity (clay swelling and dispersion, agg. slaking). 4. Infiltration, runoff and soil loss in sealing soils ( agg. slaking, raindrop impact, clay swelling & dispersion)

20 Clay depletion from the upper soil layer 20 20

21 Clay (volume %) Parent Soil Depth (cm) Loam Parent Soil Fresh Water TWW 21 21

22 Aggregate stability test 22 22

23 (Adapted from Levy and Mamedov, 2002, SSSAJ 66: ) Fresh water (ESP ~1.5) TWW (ESP ~5) TWW (ESP~8) Stability ratio Clay content (%) 23 23

24 Field - FW Field - TWW Orchard - FW Orchard - TWW 0.75 Stability ratio From: Levy et al. (2005) Depth (cm) 24 24

25 Saturated hydraulic conductivity (Lab. study) Effects of long term irrigation with TWW 25 25

26 Leaching with DW - fast vs. slow wetting 100 Sandy clay 80 Relative HC (%) ESP 1.6 (fast) ESP 1.6 (slow) ESP 5.5 (fast) ESP 5.5 (slow) Pore volume (Adapted from Shainberg et al., 2001, AJSR 39: ) 26 26

27 Leaching with DW effects of soil type & cultivation 65 Relative hydraulic conductivity (%) Clay (From Levy et al., 2005) Cultivated - fresh water Cultivated - TWW Non-cultivated - fresh water Non-cultivated - TWW Soil type Sandy clay 27 27

28 Infiltration, runoff and soil erosion 28 28

29 Runoff effects of soil texture & rate of wetting (Lab. Study) W etting rate (mm/h) Fresh water Effluent Runoff (mm) Fig. 1 Clay content (Adapted from Mamedov et al., 2001, AJSR 39: ) 29 29

30 Soil loss effects of soil texture & rate of wetting (Lab. Study) 1400 Fresh water 1400 Effluent 1200 Wetting rate (mm h -1 ) Soil loss (g m -2 ) (Adapted from Mamedov et al., 2001, JEQ 30: ) 30 30

31 The kinetics of soil reclamation by lime (From: Agassi et al., 2003, JEQ 32: ) 31 31

32 Thank you for your attention 32 32

33 International Seminar on Olive Growing and the Environment Harnessing non-conventional water Urban wastewater Guy Levy Inst. of Soil, Water & Environmental Sciences, Agricultural Res. Org., The Volcani Center Bet Dagan, Israel Madrid, 18 Nov

34 מים שפירים: איכות מי הקולחים - פרקציה אי-אורגנית סקר קולחים ארצי ( ) מליחות :(EC) חציון בין 0.87 ל :SAR חציון = 1.3 מי קולחים: ל מליחות (EC) חציון בין 1.52 :SAR חציון = 4.4 מי קולחים מוחדרים בשפד"ן (2002): מליחות = (EC) 4.8 = SAR 34 34

35 איכות מי הקולחים: מפעל הקו השלישי (שפד"ן).II מי הפקה (2002): מליחות (EC) = = SAR מי קולחים מוחדרים (2002): מליחות (EC) = = SAR 35 35

36 איכות קולחי השפד"ן (מקןר: חברת מקורות, ניטור מפעל הקו השלישי, דו"ח לשנת 2003)

37 המעבר להשקיה במי קולחים - פגיעה אפשרית במבנה הקרקע ויציבותה סיכונים אפשריים ליציבות מבנה הקרקע ויכולתה להוליך מים כתוצאה מהשקייה במי קולחים יכולים לנבוע בעיקר מרמות גבוהות (SAR) יותר של חומר אורגני ויחס ספיחת נתרן במי הקולחים בהשוואה למים שפירים, ומהתפתחות תנאים הידרופוביים בפני הקרקע

38 גרומוסול (חפץ חיים) - שטיפה במים מזוקקים; השפעה של עיבודים 40 Autumn sampling Field - fresh Field - effluent Orchard - fresh Orchard - effluent Initial HC (mm h -1 ) Relative HC (%) Depth (cm) Depth (cm) 38 38

39 Poor quality TWW EC SAR COD TSS COD* TSS* ds/m Mg/L Mg/L Mg/L Mg/L * after filtration with a 1.2 micron filter 39 39

40 Effects of leaching with poor-quality TWW on soil HC (From: A. Rosenthal. (1998). MSc thesis. Faculty of Agric. HUJI) 100 Sandy clay 75 Control Relative HC (%) (UF) High OM load RWW (F) Pore volume (V/V 0 ) 40 40

41 Quality of TWW organic loads (data taken from the DAN region plant, 2003) Year BOD TSS COD 41 41

42 Loamy sand (From: A. Rosenthal. (1998). MSc thesis. Faculty of Agric. HUJI) 100 Control 75 Low OM load RWW (UF) (F) Relative HC (%) Pore volume (V/Vo) 42 42

43 Loamy sand consequtive leaching with DW (From: A. Rosenthal. (1998). MSc thesis. Faculty of Agric. HUJI) Control Relative HC (%) 50 (F) (UF) 25 Low OM load RWW Pore volume (V/V 0 ) 43 43

44 Soil samples from Lyzimeter study effects of soil texture 0.8 Soil depth 0-20 cm Stability ratio FW 2000 FW 2002 Effluent 2000 Effluent Grumusol Loess Hamra 44 44

45 Soil samples from Lyzimeter study leaching with DW Fresh water Effluent 100 Depth 0-35cm Initial HC (cm/h) Final RHC (%) Hamra (C) Hamra Loess Grumusol Hamra (C) Hamra Loess Grumusol

46 Sandy clay leaching with DW, fast wetting 100 Sandy clay Relative HC (%) ESP 1.6 (fast) ESP 5.5 (fast) Pore volume 46 46

47 Samples from a clay soil effects of tillage Autumn Field - fresh Field - effluent Orchard - fresh Orchard - effluent 0.70 Stability ratio Depth (cm) 47 47

48 Loam leaching with DW, fast wetting 100 Loam Relative HC (%) ESP 2.1 (fast) ESP 5.4 (fast) Pore volume 48 48

49 Loam leaching with DW, fast vs. slow wetting 100 Loam Relative HC (%) ESP 2.1 (fast & slow) ESP 5.4 (fast) ESP 5.4 (slow) Pore volume 49 49

50 Saturated hydraulic conductivity field meas. Clay soil הנורחא היקשה 8 ל /ש 50 50

51 Summer FW Effluent Ks (cm h -1 ) Date 51 51

52 Runoff from a sandy clay and a loam (Lab. Measur.) (From: Agassi et al., (2003). JEQ 32: ) 52 52

53 Runoff from natural rain storms Lyzimeter study 53 53

54 Clay (volume %) Parent Soil Depth (cm) Clay Parent Soil Fresh Water TWW 54 54

55 55 55

56 56 56

57 Soil structural stability describes the ability of soil to retain its arrangement of solid and void space when exposed to different stresses (e.g., traffic, tillage, wetting & drying, etc.)

58 Processes that may affect soil structural stability (cont.): The processes that adversely affect soil structural stability are expected to occur mainly in winter when the soil is leached with rain water (i.e., water free of electrolytes); under these conditions the sensitivity of the soil clay to swelling and dispersion is high

59 Effects of DOM on clay behavior at different SARs (From: Tarchitzky et al SSSAJ 63: FV (meq/l) DOC (ppm) SAR 59 59

60 The likely effects of TWW depend on: 1. Quality of the water of origin (composition and concentration of electrolytes) 2. Level of treatment (i.e., load of organic matter) 60 60

61 cm Orchard - effluent Orchard - fresh Field - effluent Field - fresh Orchard - effluent Orchard - fresh Field - effluent Field - fresh Fluctuations in ESP between Autumn and spring 0-10 cm Autumn Spring Clay soil ESP

62 Saturated hydraulic conductivity (Lab. study) A. Leaching with TWW 62 62

63 Saline sol / TWW DW RHC Saline sol Leachate volume (ml) Sandy soil (Adapted from: Tarchitzky et al., 1999, SSSAJ ) 63 63

64 Control (UF) (F) Relative HC (%) Low OM load RWW Sandy clay Pore volume (V/V 0 ) (Adapted from: Levy et al., 1999, JEQ 28: ) 64 64

65 Israel a few facts Total Area 8, sq mi (20, sq km) (slightly smaller than New Jersey) Cultivated land ~ 400,000 ha Irrigated land ~ 200,000 ha Water used for irrigation: Total ~ 1000 million m 3 FW ~ 550 million m 3 TWW ~ 350 million m

66 Quality of TWW I. inorganic fraction (National TWW survey, ) Fresh water: Median EC = 0.87 Median SAR = 1.3 TWW: Median EC = 1.62 Median SAR = 4.4 II. organic fraction (Government regulations) TWW: BOD = 20 ppm, TSS = 30 ppm 66 66

67 Clay (volume %) Parent Soil Depth (cm) Sandy Loam Parent Soil Fresh Water TWW 67 67