Across the world, there continues to be huge volumes of wastewater
discharged directly into rivers, streams and oceans. Disposing of
wastewater is largely an issue in developing nations like Nepal.
It is important to treat the wastewater before it comes in contact
with the environment. In order to treat the wastewater and to
design the treatment system, it is crucial to know the nature of
the wastewater, as the quality of effluent largely depends upon the
influent characteristics. The capacity and efficiency of treatment
systems are designed based upon the influent concentrations and the
effluent requirements. This study analyzed 269 untreated wastewater
samples received by the Environment and Public Health Organization
(ENPHO) laboratory and characterized them in terms of pH,
Biological Oxygen Demand (BOD), Chemical Oxygen Demand
(COD), Nitrate (NO3
), Ammonia (NH4
), Total Kjeldahl Nitrogen
(TKN), Total Phosphorus (TP), Total Suspended Solids (TSS), Oil
& Grease (O&G) and Dissolved Oxygen (DO). Based on the source
of generation, these samples were categorized as domestic, industrial
or hospital wastewater. The mean BOD and COD values of tested
samples were found to be 377 mg/L and 638 mg/L respectively. The
maximum COD was found to be 10,032 mg/L and maximum BOD
was found to be 5,050 mg/L. Significant differences were found in
TKN and DO values among different types of sources. Difference
in characteristics of wastewater from different sources indicates the
necessity of their characterization before choosing treatment options.
In general, the high values of the tested parameters in comparison
to the national industrial effluent standards show the urgency of the
treatment of wastewater owing to the practice of its unsafe disposal
into the environment without any treatment.