Odor in Wastewater Management System

SAFETY CONSIDERATION DURING OPERATION
1.0 Risk assessment
The screen in the plant contains mechanical movement parts to remove the
rubbishes from the mesh to the solid waste basin. The movement parts may lead to
accidents if the workers and operators do not have good knowledge and training to
deal with it. In the other hand, all equipment and motors are working on electricity.
The possibility of electrical shocks is very high due to deal with water in all sections
of the plant. Table *** below shows the possibility and risk assessment for screen
and grit tank.Table 1: Risk identification during operations
Risk Type Factor Effects Actions Possibility
Failure of
bar screen Qualitative Ordinary
Clogging of
mesh
&Loss of
screening
Repair or
clean the
screen and
mesh
1 time each
year
Existing of
large
damps of
greasy feed
Qualitative External
Clogging of
outfall
grease
chamber
Unclogging
of outfall
grease
chamber
1 time each
year

Hazard of
Bacteria
formulation
Qualitative
and
operational
External Formulation
of scum
layer
&
Infection
Remove
scum layer
and
Cleansing
3 times
each year
Electrical
power
outage
Operational Internal - No power
- electrical
shocks
Using
emergency
power
supply
1 time each
year
2.0 What-IF analysis
Table below shows the What-IF analysis of Automatic Bar Screen and greasing
removal tanks
Unit Screen Bar (E-101) Analysis Saleh
What-if Hazard Safeguard Recommendations
High flow of Feed?
Increase the level in
the tank and
cumulative of solid
waste on the mesh
 Cleaning the screen
faster than normal
 Bypassing
 Slowdown the feed
flow
 Open drain
 Open outfall valve
High solid waste in
the feed?
cumulative of solid
waste on the mesh
 Cleaning the screen
faster than normal
Failure of feed
control valve?
Over flow + Biohazard
contamination
 Maintenance team call
 Manual calculation by
globe valve
 Isolation and cleansing
the contaminated area
 Flow Alarm install
 Isolation of the
failed valve
Unit Aeration V-102 Analysis Saleh
What-if Hazard Safeguard Recommendations
High flow of feed?
Failure of aeration in
tanks & yield
Increase the level in
the tanks
 Opening effluent valve
 Recycling to feed
storage basin
 Isolation of control
valve
 Cleansing
Low level in the
tank?
Failure of aeration in
tanks  Emergency shutdown
Odor control? Psychological stress
to people
 Mask
 Ventilation

2.0 Feed air compressor design (Add this heading and info below under Ancillary
equipment)
The aim of the compressor is to compress and feed the air into the aeration tanks
from the bottom. The height of water in the tanks was found before to be 4m while
the flowrate of air was found to be 1.08 m3/min. the required outlet pressure is
found as:
Pout=P¿+ ρgh
Pout=101,325+ ( 1000 ) ( 9.81 ) ( 4 ) =105,245 Pa
The design pressure will be taken as 25% additional where the design compressor
pressure is 131.6 kPa. The performance chart of selected compressor can be seen
in Figure below:
- The pressure ratio is 131/101.3 = 1.3
- The mass flowrate= M wt PV
RT
- The mass flowrate=29 ( 101.325 ) 1.08
8.314 (298) =1.28 kg /min (2.82lb /min) for each chamber
- There are 5 chambers so, the total mass flowrate is 14.1 lb/min (take it as 20
lb/min)