Microirrigation of wastewater effluent 

Ted Sammis 

Introduction. 

Wastewater is normally applied as land application using flood or sprinkler irrigation systems because of the plugging problems associated with using a drip irrigation system. However, researchers have applied wastewater through drip irrigation systems where the drip system was a self-flushing and tortuous -path turbulent flow emitter system and also using drip tape where the drip tape was manufactured by molding or attachment of the emitter. The research indicated that drip laterals should be flushed with a minimum velocity of 0.5 m/s every two week and that a sand media filer be used along with chlorination of 150 mg/l NaOCl for three hours every 10 days or more frequent is bacterial slime growth is detected in the sand media filter. Flushing of the sand media filter should be height enough to prevent slime build up in the filters.  However, the research was done using effluent from an activated sludge wastewater treatment plant  where the BOS and TSS are less than in a lagoon wastewater treatment system. Table 1. Wastewater from Ismailia has been applied using drip irrigation with tortuous-path emitters and no major clogging has occurred.  The wasterwater sites (table 2) in Wisconsin have not shown any plugging problems and the TSS and BOD were higher than the effluent from the wastewater treatment plant at Davis California  and the lagoon system in Egypt. 

The best management practice  for the application of effluent  from a lagoon wastewater system  should be the use of a drip system than has tortuous -path emitters or drip tape with molding or attachment emitters. Also  the system  should have both a sand media and screen filter and chlorine be injected into the system along with a regular flushing cycle.

Table 1. Water quality effluent from different Wastewater treatment systems.

Parameter/Site

Ojinaga, Mexico

Las Cruces, USA

Ismailia, Egypt

Davis California

Treatment Train

Screens/Primary/Anaerobic  lagoon

Screens/Primary/Aerated Lagoon

Screens/Grit/Primary/Aerated /Facultative Lagoon

Activated sludge wastewater treatment plant

Disinfection

No

No

No

Yes

Effluent BOD, mg/L

29-43

30

46

15.2

Effluent TSS, mg/L

15

30

23

8.3

Effluent TN, mg/L

14-37

45

45

 

Effluent TDS, mg/L

1,950-2,220

2,000-3,000

550

 

Soil SAR, mg/L

5.5 7.0

N/A

N/A

 

Flow, m3/day

6,048

1,514

90,000

 

Land Application. Area, ha

500

22.3

200-2000

 

Rainfall, mm/year

280

216

<2.0

 

PET, mm/year

2,450

2,220

2,341

 

Selected Crop(s)

Eucalyptus/Hybrid Popular

Creosote Bush, FourWing Saltbush, Mesquite

Arizona Cypress, Afghan Pine, Eucalyptus, and others

 
Irrigation system  flood sprinkler Drip turbulent flow emitters Drip tape. 

Table 2.  Effluent  of septic for different locations in Wisconsin 

Parameter/Site

Barron Rest Area  Fond Du Lac Home Wood -School

Treatment Train

Septic Tank Septic Tank Septic Tank

Disinfection

no no no

Effluent BOD, mg/L

173 110 24

Effluent TSS, mg/L

51 20 49

Effluent TN, mg/L

185 45 92

Effluent TDS, mg/L

2906 6718 1921

Type of emitters

pressure compensating emitters 0.65gph pressure compensating emitters 0.65gph  

None of the system have been running for more than 3 years. Plugging may still be a problem because no chlorination is occurring 

 

Reference Hills, D. J. and M. J. Brenes, 2001. Microirrigation of wastewater effluent using drip tape  Applied Engineering in Agr. vol. 17(3):303-308

Bohrer R. M. and J. C. Converse. 2001. Soil treatment performance and cold weather operations of drip distribution systems  On Site wastewater treatment prodceedings of the ninth national symposium on infividual and samm community sewage system March 1-14 For Worth, Texas  pp561-584