Organic Waste Recycling

Land treatment of sludge 451

require less preparation and can be used with a wide variety of crops. Ridge-
and-furrow and overland flow are suitable to level land and sloped land,
respectively; they also minimize aerosol-related pathogens and aesthetic
problems.
Tank trucks, farm tank wagons and tractors are also effective in applying
sludge on crop lands in which sludge is pumped from roadway onto the field.
Commercial tank trucks with plow furrow cover are available where sludge is
discharged in furrow ahead of plow mounted on rear of the trucks.

Table 9.6 Transport modes for sludge (Knezek and Miller 1976)

Type Characteristics

Liquid sludge

Rail tank car

Barge

Pipeline

Vehicles

Tank truck

Farm tank wagon and

tractor

Sem-solid or solid sludge

Rail hopper car

Truck

100 wet tons (24,000 gala) capacity; suspended solids will

settle while transit.

Capacity determined by waterways; Chicago has used

1,200 wet tons (290,000 gal) barges.

Need minimum velocity of 1 f.p.s. (30 m/s) to keep solids

in suspension; friction decreases as pipe diameter

increases (to the fifth power); buried pipelines suitable

for one-year use.

Capacity-up to maximum load allowed on road

Can have gravity or pressurized discharge. Field

trafficability can be improved by using floatation tires.

Capacity: 830 – 3,000 gal. Principal use would be for

field application

Need special unloading sites and equipment for field
application
Commercial equipment available to unload and spread on
ground need to level sludge piles if dump truck is used.
a 1 gallon = 3.785 L