Wastewater Treatment Assignment

Lab Report 1
LAB REPORT 1
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Lab Report 2
Objectives
The main objective of the lab was to acquire the essential information regarding
wastewater treatment, especially, the stimulated sludge process. In this lab, the wastewater
quality enhancement was illustrated by synthetic wastewater lab tests. Therefore, through the lab,
various parameters were to be measured, and a graph plotted from the data obtained.
Introduction
Wastewater treatment for organic carbon removal is carried out in three conventional
stages. Namely, the primary treatment, secondary treatment, and tertiary stages.
Primary treatment
The primary treatment of wastewater treatment is a three-step process. Firstly, screening
is carried out to remove large objects followed by grit removal which serves to eliminate denser
material such as sand, broken glass or dirt. Subsequently, it is passed through sedimentary tanks
where sludge settles, and the less dense oil and grease are skimmed off from the surface.
Secondary treatment
Secondary treatment is also referred to as sludge activated process. in this process, “the
primary treated wastewater is mixed with biomass in the aeration tank” to form a mixed liquor
(Ramalho, 2013). Additionally, diffused air is passed through to provide oxygen to decompose
the organic compounds through microbiological processes. Then, sludge sediments are
continuously “removed and returned to the aeration tanks to maintain the biological population”
(Mamais, 2014). Consequently, the overflow obtained from the settlement tanks forms the

Lab Report 3
secondary wastewater. Notably, all the oxygen-dependent substances are removed from the
system by biochemical processes.
Furthermore, organic matter is converted to the gaseous state in the presence of oxygen.
The process is performed to obtain energy necessary for the manufacture of new cell tissue and
their maintenance. The processes involved in secondary treatment are illustrated through
equations as follows.
COHNS (organic substances)+bacteria +O2
CO2+ N H3 +energy +other products (oxidation process)
COHNS +bacteria+O2 +energy C5 H7 O2 (synthesis)
5 O2+ C5 H7 O2 N H3+ 5CO2 +2 H 2 O+energy
Tertiary treatment
In this process, the high-level effluents from the activated sludge process such as organic carbon,
phosphorus, and nitrogen are removed.
Procedure
Firstly, Synthetic wastewater was made under constant phosphorus, nitrogen, and carbon
in the ratio 1:15:100 respectively. Secondly, a mixture of synthetic water and biomass from the
wastewater treatment plant was obtained. After that, microbial activities were enhanced by a
supply of oxygen at a temperature of 24oC. Then Dissolved Oxygen (DO) of the sample was
measured continuously in an airtight container. Notably, all these measurements were carried out
after a time interval of 3 minutes. Thereafter, carbon removal was calculated from the equation: