WASTE WATER TREATMENT

 Waste water and its characteristics:

The waste water  which is generated from 'kitchens, bathrooms, and other wash areas' is called "Grey water".
The waste water which is generated from 'Toilets' is called "Black water".

Grey water + Black water = Waste water

          In general, 80% of water used by the population comes out as waste water. If the water availability is 135 lpcd (Municipal+other sources), we consider 108 lpcd as the waste water generation. 

General characteristics of waste water is presented as below:

PARAMETER	HIGH	MEDIUM	LOW
COD Total	1,200	750	500
COD Soluble	480	300	200
COD Suspended	720	450	300
BOD	560	350	230
VFA (as acetate)	80	30	10
N total	100	60	30
Ammonia-N	75	45	20
P total	25	15	6
Ortho-P	15	10	4
TSS	600	400	250
VSS	480	320	200

What is Faecal sludge and septage?

The sludge produced by on-site sanitation systems like septic tanks is called "Septage".

The slude produced from pit toilets is called "Faecal sludge".

It is highly polluting than domestic waste water.

Faecal sludge quantity and quality

Supply based: It is estimated that 230 lts of Faecal Sludge is produced per capita per year.

Demand based: No.of septic tank emptying incidents X Capacity of the septic tank cleaning truck

Characteristics of Faecal sludge/septage is presented below:

Constituent All are units but for PH are in mg/l	Average
PH	1.5 - 12.6
Total suspended solids	12,862
Biochemical oxygen demand	6,480
Chemical oxygen demand	31,900
Ammonia-Nitrogen	97

 

Faecal sludge Management system (FSM):

Source: Bill And Gates Foundation