SEWAGE 化学特性,用途語,生産方法
农业用途
Sewage is watery material from chemical plants,
municipal waste and septic systems. Safe disposal of
large quantities of sewage and septage poses an economic
problem.
The end products of all sewage treatment processes
are sewage sludge and effluents. Both components of
sewage are used to increase crop production. Sewage
sludge is the solid portion produced during sewage
treatment. Sewage effluent is essentially clear liquid,
containing low concentrations of plant nutrients and
traces of organic matter, which after chlorinating can be
used for irrigation purposes. Common methods for
disposal of sewage include its burning, burial and
composting.
On average, sewage contains 22 ppm, 5 ppm and 15
ppm of NPK, respectively. In addition, it contains
micronutrients like Zn, Cu, Fe and undesirable materials
like heavy metals (Ni, Cd, Pb). All sewage and septage
sludges generated annually would replace only about 1 % ,
4% and0.5% N, P, K, respectively. Sewage is
allowed to stand in a settling tank or a septic tank to let the
heavier portion to settle, and for organic matter to undergo preliminary fermentation and oxidation. This
oxidized sludge is called activated sludge which is
odorless. It contains 3 to 6% N, 2% P and 1 % K on dry
weight basis.
Raw sewage should not be used directly for growing
vegetables as it may contain toxic elements and bacteria
which are dangerous to health. Treated sewage
wastewater can be used on fields and thus plowed back
into the soil. Field crops grown with sewage irrigation
include: (a) fodder crops like oats, sorghum, maize,
(b) sugar cane, and (c) vegetable crops like cabbage,
cauliflower, potato, lady's finger, brinjal and leafy
vegetables.
Waste material, usually liquid, originating from
households (kitchen, bath and washings), but not
including urine or feces, is referred to as sullage.
SEWAGE 上流と下流の製品情報
原材料
準備製品