Sanitary Wastewater Treatment

A sanitary wastewater treatment eliminates microbial contamination and treats all contaminating agents in form of BOD, COD and TSS down to the environmental standards. This wastewater contains organic substance, fat, carbohydrate and solid particles that must be treated before it returns to the natural cycle or to be reused.

The key process in the sanitary wastewater treatment is biological treatment methods: aerobic and/or anaerobic.

Removing of the suspended solids in sanitary wastewater by physical methods and separation of fat and other low-density components by means of floatation process, and then, use of aeration and sedimentation unit are the most common type of treatment. By using this package, wastewater can be used to irrigate or discharge into rivers and sea.

Since the past years, FARAN has collected lots of successful experiences in designing and fabrication of prefabricated skid-mounted wastewater treatment packages for small capacities up to 200 cubic meters per day and construction of civil based treatment plants for the large scale applications.

Wastewater Composition	Poor	Moderate	Strong
Fresh Sewage Color	gray	gray	gray
Old Sewage Color	black	black	black
BOD5 (mg/l)	200	250	600
COD (mg/l)	400	700	1000
TSS (mg/l)	100	200	300
TKN (mg/l)	15	40	60

The treated wastewater quality which is discharged from the sanitary treatment package must be in accordance to the environmental standards as follow:

Wastewater Composition	Discharge into Absorbing well	Discharge into Surface waters	Agriculture and Irrigation consumption
BOD5 (mg/l)	30	30	100
COD (mg/l)	60	60	200
TSS (mg/l)	–	40	100
Nitrate (mg/l)	10	50	–

In some projects, the end user is interested in recycling the treated stream for irrigation and other applications. In these cases, some complementary processes such as ultrafiltration, advanced oxidation and reverse osmosis depending upon the desired quality may be required.