Hi All!

For a Trickling Filter design, raw domestic sewage flow rate varies between 0.1 to 0.3 MLD, taking into account the following sewage and the treated wastewater characteristics, and considering that the said sewage is first collected in a septic tank of appropriate size and the effluent from the septic tank is sent to a well of reasonable size, is it necessary to have screen and grit chambers for such a system. Available space is not a problem but economics of the system is prime.

Can our friends let me allow to go ahead with a system having just a septic and feed supply tank without incorporating Screen & Grit chambers?

The attention of all is specifically requested.


Parameters of the Sewage be treated:

Sr. No.         Parameter                                Numeric Value.
                         
01                   pH                                               6.5 – 8.5      
02                   TSS                                             400-500 ppm.      
03                   BOD5 @ 20 oC.                            200-300 ppm.      
04                   COD                                            400-500 ppm.      
05                   Oil & Grease                                  20-25   ppm.
06                   NH3-N                                           20-25   ppm.
07                  Temperature                                     25-35 oC.
08                  Total Coliform                       107-108MPN/102 ml.

Pameters of the treated Wastewater:

Sr. No.      Parameter                                      Numeric Value.
                         
01                   pH                                             5.5 – 9.0      
02             Temperature                                    25-35   C.      
03             BOD5 @ 20 oC.                                ≤ 30  ppm.      
04             TSS                                                 ≤ 1500  ppm.      
05             Oil & Grease                                     ≤    10  ppm.      
06             NH3-N                                              ≤      5  ppm.

Regards

JB

Mr. Grrun


Thanks for the immediate response. Actually the calculations for Screen chamber ended with just one screen bar with the depth of chamber ended up with 1 cm. I was trying to bring to the attention of all that small sewage treatment units require special consideration rather than following standard design calculation.

How far I am true is left for open for further discussion and suggestions.

Regards

JB

when u say trickling filters, the floating matter needs to be screened. U can screen at suction side of the pumps, else if it is gravity flow think of screening it at the inlet of septic tank. u donot go in design, just select 0.3 m x0.3m screen of required spacing.

As for grit, if u have got enough settling time in Septic tank, most of it shall settle there.