MBR Presentation

1. WHAT IS
SEWAGE
TREATMENT
PROCESS,
IMPORTANCE
& SOURCE
 Sewage treatment is the process of removing contaminants from wastewater
and household sewage, both effluents and domestic. It includes physical,
chemical, and biological processes to remove physical, chemical and biological
contaminants.
 It’s objective is to produce an environmentally safe fluid waste stream and a
solid waste suitable for disposal or reuse.
 The objective of sewage treatment is to produce a disposable effluent without
causing harm to the surrounding environment, and prevent pollution.
 It is very important to provide some degree of treatment to wastewater before
it can be used for agricultural or landscape irrigation or for aquaculture.
 The principal objective of sewage treatment is generally to allow human
effluents to be disposed of without danger to human health or unacceptable
damage to the natural environment.
 According to a research, a large number of people die from water born
diseases in most of the developing countries. Therefore, it is very important to
get the proper treatment of the water for a healthy living.
 Sources of wastewater;
 Human waste
 Washing water
 Rainfall collected on roofs, yards, hard-standings
 domestic sources
 Direct ingress of river water
 Highway drainage
 Industrial waste

2. WASTE WATER TREATMENT PROCEDURE
Sewage treatment generally involves three stages, called as follows;
 PRIMARY TREATMENT:
Primary treatment removes materials that can be easily collected from the raw sewage before they damage
or clog the pumps and sewage lines of primary treatment clarifiers trash, tree limbs, leaves, branches etc..
The settled and floating materials are removed and the remaining liquid may be discharged or subjected to
secondary treatment. Examples for primary treatment are, Bar Screen, Grit and Grease Removal Process
 SECONDARY TREATMENT:
Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically
performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may
require a separation process to remove the microorganisms from the treated water prior to discharge or
tertiary treatment.
 TERTIARY TREATMENT:
The purpose of tertiary treatment is to provide a final treatment stage to raise the effluent quality before it
is discharged to the receiving environment (sea, river, lake, ground, etc.). More than one tertiary treatment
process may be used at any treatment plant. If disinfection is practiced, it is always the final process. It is
also called "effluent polishing."

3. Introduction
• Riyadh University Wastewater Treatment Plant is
designed to treat the total raw sewage that will be
collected from various university applications. Both of
suspended solids and biodegradable organic matters
will be reduced through the treatment stages to an
acceptable limit. The plant is capable to produce
treated water that meets water reuse standards in
volume and quality.
• The combination of both Extended Aeration
system and MBR technology, give this plant a unique
and special value as it is expected to achieve the best
water quality (micro-filtrated water) among other
typical wastewater treatment plants. Moreover, it will
further save space and cost.
• The primary treatment is designed to handle up to
a daily flow of (10,400 m3/d) in phase I and will cover
the future expansion up to (13,000 m3/d) all in one
stream. In the other hand, phase 1 biological
treatment will be able handle up to a daily flow of
10,400 m3/d in four streams, and able to handle the
future expand up to (13,000 m3/d) in five streams.

4. BASIC DESIGN
PARAMETERS

5. COARSE
SCREENS
Two coarse screens are available, one is
mechanical in-duty screen and the other is a
manual standby one. Both screens have clear
bar opening of approximately 25 mm. The
function of these screens is to collect coarse
solids and large material and remove large
trash in the influent sewage in order to protect
the mechanical part of the pumps as well as to
prevent pipes clogging. The accumulated
materials on the screen is cleaned either
mechanically or manually to the box screen
according to the type of the screen in duty. The
raw sewage passed through the coarse screens
goes to the Grit & Grease removal unit as a
next treatment step.

6. GRIT & GREASE
REMOVAL UNIT
• A considerable amount of grit is carried along
with the flow of sewage. If these grit particles are
not removed, they may damage the mechanical
parts of the treatment system. Grit particles are of
large size and have a high density compared to the
organic particles in sewage.
• The Grit and Grease Removal system operates to
separate solids that have a specific gravity larger
than water by precipitation (rags, grit and large
suspended matters). Floating matters, which have a
specific gravity less than water, such as scum, fat,
grease, are separated by flotation techniques.
Precipitates are collected by a mechanical scraper
at the bottom, and disposed out of the unit by air
blower. Meanwhile, a periodic skimmer moves over
the surface of the water to collect buoyant matters
and dispose of them.
• The raw sewage water is entered to the grit and
grease chamber at one end of the tank and is
discharged at the opposite end of the tank. An
aeration system is provided along one side of the
aerated compartment. A spiral flow of the sewage
is created from the inlet to the outlet of the
chamber by the aeration to provide a cyclic
momentum for the flow.

7. EQUALISATION TANK • A two compartment,
concrete influent
balancing tank is provided
to equalize incoming flow.
The tanks are equipped
with coarse bubble
diffusers assuring a good
mixing and preventing
septic results. These
diffusers are connected
with the air blowers
through the piping
network.

8. pH CORRECTION SYSTEM
• A PH correction system is provided
to condition influent before entering
the anoxic zone (PH is corrected in the
equalization tank).
• PH adjustment (neutralization) will
be carried out on raw wastewater
before being pumped to further
biological process, to provide the
required alkalinity that was consumed
through nitrification process.
According to the pH analyzer installed
at the discharge pipe of the
submersible pumps, a dosing rate of
basic (50% caustic soda, NaOH) is
chosen automatically by the PLC in
such a way to keep pH within the range
of (7.5 – 8.0) at the chosen set point.
The pH meter has alarm settings for
both the Low and High levels (Low =
6.5, High = 8.5).

9. ROTARY DRUM SCREENS
• Rotary Drum Screens
correction system is installed at
the top inlet distribution channel
of the anoxic tank to make final
screening up to 2mm. The
purpose of the fine screen is to
remove material greater than 2
mm diameter from the influent
wastewater to prevent
detrimental effects on the
operation of the membrane
process. All flow pumps to the
membrane tank are passed
through drum screens. Equipped
with two wash pumps that both
work periodically. The main task
of those pumps is to clean the
screen openings from the
accumulated debris by clean
water. The flushed water will
pass the screen toward the
equalization tank through the
drainage system.

10. ANOXIC TANKS
• Anoxic zones in wastewater are useful for
nitrogen removal. Some wastewater has a
high nitrate and nitrite content, and the
treatment process must break down those
compounds to avoid causing nutrient
pollution when the plant discharges its
effluent back into the environment.
• In anoxic zones, when bacteria break down
the nitrogen products, the separation of the
molecules releases oxygen, which the
bacteria need to thrive. Because the
biodegradation of nitrogen products naturally
releases oxygen, the bacteria in anoxic tanks
like denitrification basins do not require
supplemental oxygen from diffusers or
surface aerators.
• Agitation is required to blend the basin
contents to increase process efficiencies. This
is achieved by means of mixers.

11. AERATION TANKS
A complete air diffusing system composed of
air blowers with piping and air diffusers take
care of the oxygen input to the system, by
diffusing the air inside the water to maintain
oxygen transfer for aerobic treatment. A
dissolved Oxygen (DO) meter is placed in the
tank to monitor and maintain the DO level in
the wastewater (ranging from 1.5- 3 ppm),
and hence gives indication for the air mixing
efficiency.
Aeration is the process of adding air into
wastewater to allow aerobic biodegradation
of the organic materials.

12. MEMBRANE
BIOREACTOR TANKS
• Four membrane tanks are provided and are equipped with membrane sets with a
suitable air scouring system. Treated effluent from the MBR tanks will overflow to the
final effluent sump.
• The mixed liquid from the Bioreactor tanks flows by gravity to the MBR tanks
Where liquid solid (biomass) separation occurs outside in ultra filtration membranes.
• The membranes are immersed directly into the aerated mixed liquor. The treated
permeate is drawn through the membranes by gravity and discharged from the
system. Organic matters in wastewater are biologically degraded (digested) in the
aerobic bioreactor, and then discharged continuously and evenly into four MBR tanks.
The treated permeate is drawn through the membranes & discharged from the system
by gravity to the chlorine contact tank. Air is continuously supplied to the MBR tanks
through blowers for the sake of membrane scouring, by using coarse bubble diffusers.
• Sludge liquid (biomass) shall be fed continuously from the bioreactor tanks toward
the membrane tanks by means of gravity, and returned back to the Sludge
Recirculation Pit, then to the Bioreactor tank by utilizing the submersible pumps.
• In this project four MBR tanks (one for each stream) are installed. Each tank has
15 modules in one array.

13. CHLORINE CONTACT TANK
& CHLORINATION SYSTEM
• The treated effluent after filtration flows
into chlorine contact tank by gravity,
chlorination and disinfection is done by
using sodium hypochlorite. Chemical dosing
station is used to add chlorine in the treated
water.

14. MEMBRANE
RELAXATION
SEQUENCE
• Two types of operations can be applied during filtration
process, simple continuous filtration and intermittent
filtration. In intermittent filtration process, filtration is
suspended while air diffusion is continuous, Air diffusion
occurs in the absence of permeation, enabling effective
cleaning of membrane surface. Although a control device is
required to start and stop filtration, intermittent filtration is
recommended when you need higher filtration flux. This
procedure is beneficial in removing any reversible fouling that
may have accumulated on the membrane surface. It is
recommended to set the intermittent filtration in 9 minutes
of continuous filtration and 1 minute of suspension (Toray
recommendation).
• The SCADA will automatically carry out this procedure
(intermittent cycles) as long as no inhibits are in place. This
procedure is inhibited during a chemical clean and during
diffusers flushing sequence.

15. RAS WAS PIT
• Sludge from the MBR Tanks overflows to the
RAS (return activated sludge) WAS ( Pit. The pit is
equipped with sludge feed pumps, these pumps
circulate sludge to the bioreactors by mixing with
the incoming raw sewage at the distribution
chamber thereby re-circulating the return sludge
back to the Anoxic and Aeration Tanks, ensuring
the de-nitrification process by providing No3
compounds.
• Excess waste sludge in the pit will be pumped
to the Sludge Holding Tank.
• RAS: It maintains the correct concentration of
activated sludge in the aeration tank, ensuring
that the required degree of treatment can be
achieved within the designated time.
• WAS: Kind of sewage treatment that blows
oxygen (or air) into unsettled, raw sewage, which
digests pollutants and organic content to keep
the biological system in balance.

16. SLUDGE
DEWATERING BELT
PRESS
• Waste pumped sludge
coming from the RAS sump is
directed to the Sludge Break
Tank. This tank is equipped
with an aeration system. Belt
Press Sludge Dewatering
system is provided to handle
the sludge and change to
sludge cakes.
• The Sludge break tank is
mixed to ensure sludge
homogenous and septic free
conditions. Coarse bubble
diffusers are used to perform
mixing for the sludge break
tank. No-clogging diffusers
are attached to the down
comer air pipes at the
specified immersion depth to
produce the coarse size air
bubbles.