Organic Waste Recycling

Aquatic weeds and their utilization 349

description Gravitational settling of solids (and constituent contaminants) i

n

ponds/marsh settings. Particulates filtered mechnically as water passes through substrate, rout

e

masses, or fish. Inter particle attractive force (Van der Waals force) Formation of, or co-precipitation with, insoluble compounds.Adsorption on substrate and plant surfaces. Removal of colloidal solids and soluble organics by suspended, benthic,and plants- supported bacteria: bacterial nitrification/denitrification.

Bacteria

and viruses

I

Refractory

organics

I S P

Heavy

metals

I P P

Phosphorus I P P

Nitrogen I P

BOD I P

Colloidal

solids S S S P

Contaminant affected

a

Settleable

solids

P S

Mechanism Physical Sedimentation Filtration Adsorption Chemical Precipitation Adsorption Biological Bacterial metabolism

b

Table 7.7 Contaminant removal mechanisms in aquatic systems