Wastewater treatment process overview

Summary

This video tutorial provides a comprehensive overview of wastewater treatment, explaining the key stages: preliminary, primary, secondary, and tertiary treatments. The process involves mechanical, biological, and chemical methods to purify water. It covers the separation of solid waste (sludge) and the treatment of liquid waste. The video also discusses sludge treatment, which includes digestion, thickening, and dewatering to make sludge usable as a soil conditioner. The biological treatment stage, which uses microorganisms, is highlighted as the most critical step in ensuring water purification.

Takeaways

• 💧 Wastewater treatment involves two main parts: liquid treatment and solid (sludge) treatment.
• 🚰 The liquid treatment is divided into four stages: preliminary, primary, secondary, and tertiary treatments.
• 🛠️ Preliminary and primary treatments are mechanical processes to remove large solid particles from the water.
• 🧹 Bar screens and grit removal systems are used in the preliminary treatment to separate large items like toys or grease from the water.
• 🏗️ In the primary clarifier, smaller particles are allowed to settle and form a sludge layer at the bottom of the tank.
• 🌱 Secondary treatment involves biological processes, utilizing microorganisms to break down nutrients and waste in the water.
• 🌬️ Aeration basins are used in secondary treatment, introducing air to encourage aerobic bacteria to digest organic waste.
• 🦠 The tertiary treatment (chemical treatment) uses chemicals like chlorine or UV disinfection to remove harmful microorganisms.
• ♻️ Sludge from both primary and secondary treatments undergoes digestion, thickening, and dewatering to prepare it for use as a soil conditioner.
• 🔥 Methane gas produced during sludge digestion can be used as a fuel source to power equipment within the wastewater treatment plant.

Q & A

What are the two main components of wastewater treatment?

The two main components of wastewater treatment are the treatment of the liquid part (water) and the treatment of the solid part (sludge).

How is the liquid part of wastewater treated in general?

The liquid part of wastewater is treated in four stages: preliminary, primary, secondary, and tertiary (chemical) treatment.

What happens during the preliminary treatment of wastewater?

Preliminary treatment is a mechanical process where large solid materials, such as debris and toys, are removed using bar screens and grit removal systems.

What is the purpose of primary treatment in wastewater processing?

Primary treatment focuses on mechanically separating smaller particles from the water, using clarifiers to allow sedimentation of solids to form primary sludge.

How does secondary treatment differ from primary treatment?

Secondary treatment is biological and uses microorganisms to break down nutrients in the water, with processes such as aeration and anaerobic treatment to further clean the water.

Why is tertiary treatment necessary in wastewater processing?

Tertiary treatment is required to remove any remaining microorganisms, including potential pathogens, through chemical processes like chlorination, ensuring water is safe for discharge.

What is the role of microorganisms in secondary wastewater treatment?

Microorganisms, especially aerobic bacteria in aeration basins and anaerobic bacteria in anaerobic chambers, feed on the nutrients in the wastewater, breaking them down and cleaning the water.

What is sludge, and how is it treated in the wastewater process?

Sludge is the solid waste removed during both primary and secondary treatments. It undergoes digestion, thickening, and dewatering to make it safe and useful, such as being used as a soil conditioner.

How is methane gas used in wastewater treatment?

Methane gas is produced during the anaerobic digestion of sludge by methanogenic bacteria. The methane can be captured and used as fuel to power generators and pumps in the wastewater treatment plant.

What are some potential environmental concerns with chlorine use in tertiary treatment?

High concentrations of chlorine can be harmful to aquatic ecosystems if discharged into water bodies, potentially harming flora and fauna. It's important to reduce chlorine levels through additional processes like sulfur dioxide treatment or UV disinfection.

Outlines

00:00

🚰 Introduction to Wastewater Treatment Processes

The video begins with an introduction to wastewater treatment, emphasizing the two main components: the treatment of the liquid part (water) and the solid part (sludge). The overview highlights the importance of understanding each stage of wastewater treatment, which includes preliminary, primary, secondary, and tertiary treatments. Wastewater collected from public channels and homes is first pumped to the treatment station for processing.

05:00

⚙️ Preliminary and Primary Treatment

The focus shifts to the preliminary treatment, which uses mechanical processes to remove large solid particles from the water. Bar screens and grit removal are used to separate items like toys or other solids. The primary treatment then separates smaller solid particles by allowing them to settle through gravity in a primary clarifier. Both preliminary and primary treatments are mechanical in nature.

10:02

🦠 Biological Treatment in the Secondary Stage

In the secondary treatment, biological processes are used to purify water. Aerobic bacteria in aeration basins break down organic matter. This step also includes an anaerobic chamber where anaerobic microorganisms further treat the water. This biological stage is crucial in reducing nutrient levels, aided by bacteria, before the water moves on to the next phase.

15:04

🔬 Chemical and Tertiary Treatment

The tertiary or chemical treatment phase involves removing remaining harmful microorganisms using chemicals like chlorine or UV disinfection. This step is vital for ensuring that no dangerous pathogens remain in the treated water. However, caution is taken to manage chlorine levels, as excess chlorine can harm aquatic life and ecosystems when the water is discharged back into streams.

💡 Handling Chlorine and Final Water Disinfection

Further chemical processes help reduce chlorine concentration, which can otherwise be toxic to humans and aquatic life. Sulfur dioxide or UV disinfection methods are used to neutralize the remaining chlorine, ensuring that the treated water is safe for release. The importance of balancing these chemicals to avoid harmful effects is emphasized.

🌾 Sludge Treatment Overview

This part explains the treatment of solid waste (sludge) separated during the earlier stages. Sludge digestion, thickening, and dewatering are the key steps in converting sludge into a useful byproduct. Methane generated from anaerobic digestion is harnessed as an energy source for running some parts of the wastewater treatment plant. The process results in a thickened sludge that can be used as a soil conditioner.

🌀 Sludge Dewatering and Disposal

The final step in sludge treatment is dewatering, where centrifuges separate excess water from the sludge, leaving a solid cake-like structure. This dewatered sludge is then transported to landfills for disposal, but it can also serve as a nutrient-rich soil conditioner due to its valuable components. This completes the solid waste management process in wastewater treatment.

🔄 Summary of Wastewater and Sludge Treatment Processes

The video concludes with a recap of the entire wastewater treatment process, covering both the liquid and solid parts. Mechanical, biological, and chemical treatments work in conjunction to purify water, while sludge treatment ensures the safe disposal or reuse of solid waste. The secondary (biological) treatment is highlighted as the most critical phase in purifying the water before it is discharged back into natural water bodies.

Keywords

💡Wastewater Treatment

Wastewater treatment refers to the process of removing contaminants from sewage or industrial waste to make it safe for the environment or reuse. In the video, it is divided into two parts: liquid treatment and sludge treatment, with four main stages of the liquid treatment process—preliminary, primary, secondary, and tertiary.

💡Preliminary Treatment

Preliminary treatment is the first stage of wastewater treatment where large solid objects like toys or paper are removed mechanically using bar screens. This process is essential to ensure that these large objects don't damage the equipment or affect subsequent stages of the treatment process.

💡Primary Treatment

Primary treatment involves the removal of smaller solid particles through sedimentation. This process happens in a primary clarifier, where the solids settle at the bottom, forming 'sludge.' This sludge is later processed separately in the sludge treatment phase.

💡Secondary Treatment

Secondary treatment, also called biological treatment, uses microorganisms to break down organic matter in the wastewater. Aerobic bacteria in the aeration basin consume the nutrients, which helps to clean the water further. This phase is crucial as it removes the bulk of organic pollutants.

💡Tertiary Treatment

Tertiary treatment is the final stage of wastewater treatment, where chemical processes like chlorination or UV disinfection are used to kill any remaining harmful microorganisms. This ensures that the water is safe for discharge into streams or for reuse. This step also involves dechlorination to prevent environmental harm.

💡Sludge Treatment

Sludge treatment involves managing the solid waste (sludge) collected from the primary and secondary treatments. It is processed in three stages: digestion, thickening, and dewatering. This process turns potentially harmful sludge into a resource that can be used as a soil conditioner.

💡Aeration Basin

The aeration basin is part of the secondary treatment process, where wastewater is mixed with air to support the growth of aerobic bacteria. These bacteria consume organic material in the wastewater, breaking it down and helping to purify the water. The process requires continuous aeration to maintain oxygen levels for the bacteria.

💡Clarifier

A clarifier is a large tank where solids settle out of the water. There are two types in the wastewater treatment process: the primary clarifier, which removes large solids, and the secondary clarifier, which helps remove coagulated nutrients and bacteria after biological treatment. Clarifiers play a key role in sludge formation.

💡Chlorination

Chlorination is a chemical process used in tertiary treatment to disinfect the treated wastewater by killing any remaining microorganisms. Chlorine can be applied in various forms, including gaseous, liquid, or tablet form. While effective, it can pose environmental risks, so careful control of chlorine levels is necessary.

💡Sludge Digestion

Sludge digestion is a key part of sludge treatment where anaerobic bacteria break down organic matter in the sludge. This process generates methane gas, which can be used as an energy source to power the wastewater treatment plant. It helps reduce the volume of sludge and produces valuable biogas.

Highlights

Introduction to the basics of wastewater treatment, covering both liquid and sludge treatment.

Wastewater treatment is divided into two parts: liquid treatment and sludge treatment.

Liquid treatment is further divided into four stages: preliminary, primary, secondary, and tertiary treatment.

Preliminary treatment uses mechanical methods to separate large solid particles, like bar screens for removing large debris.

Grit removal in preliminary treatment uses gravitational forces to separate grease and fat from the wastewater.

Primary treatment involves a primary clarifier, which allows smaller particles to settle at the bottom to form sludge.

Secondary treatment, also known as biological treatment, uses microorganisms to break down the remaining organic materials in the wastewater.

Secondary treatment has two parts: aeration basins (for aerobic bacteria) and anaerobic chambers (for anaerobic bacteria).

Secondary clarifier helps sediment the coagulated particles, forming secondary sludge.

Tertiary treatment, also known as chemical treatment, uses chlorination and sometimes UV disinfection to kill any remaining microorganisms.

Chlorine must be removed after tertiary treatment to avoid harming aquatic life when the water is discharged.

Sludge treatment has three stages: digestion, thickening, and dewatering.

Methanogenic bacteria in sludge digestion produce methane gas, which can be used as fuel to power some wastewater treatment processes.

Centrifuges in the dewatering process remove excess water from sludge, turning it into a solid cake that can be used as soil conditioner.

The overall process of wastewater treatment ensures that both the liquid and solid components are treated and made safe for the environment.

Transcripts

[Music]

Welcome Friends uh in this video

tutorial I'm going to talk about uh the

basics of

uh wastewater treatment and uh we'll be

seeing uh the different stages of

wastewater treatment and how the

wastewater treatment is being done now

uh I first tell you about the wastewater

treatment and in any kind of wastewater

treatment there is two different way of

handling it uh one is uh the Water

wastewater treatment which is only about

the watery part or the liquid part and

the second part is the treatment of the

solid part that are dispense dispensed

in the water which is called the sludge

treatment so we have to talk about both

of the treatments now in this picture in

this video tutorial I'm going to talk

about the basic overview of the

treatment system but uh in any kind of

Wastewater system uh you must know the

overview otherwise you cannot correlate

each of the steps because each of the

steps are because there are a lot of

different steps

and those STS are done finally to get

rid of all the all the contaminants that

are present in the water now in this

case what we are looking at uh the water

is collected from the public Channel

network in uh from through these pipes

and the small pipes in the bigger pipe

then then those pipe contains all this

waste Waters from from house supplies or

something from Wastewater storm water

basin also and it will come into the

palm station now the palm station will

pump it towards the first round of

treatment which is called the

preliminary treatment now first

treatment is the preliminary second

treatment is a primary then the

secondary then finally the chemical

treatment or the tertiary treatment has

been conducted so if we divide it in uh

we can divide into four parts the liquid

treatment is divided into four parts

preliminary primary secondary and

tertiary so this is a preliminary

treatment uh then then the primary

treatment so this is a primary then

secondary and then tertiary the this

four type of treatments are there now in

the preliminary treatment this only the

mechanical treatment is being done and

any in many wastewater treatment plans

this primary and preliminary treatment

are fused together and they call it the

primary treatment now in this primary

treat treatment basically the physical

apparatus are used to mechanically

separate uh particles from the water

because the water which we collect

contains solid as well as liquid parts

now uh the liquid parts they are also

having the nutrient sources because this

waste water contains the human waste

that means we are having uh those

protein products we are having those

carbohydrate or sugar products and all

these things uh in in it and also the

fatty fatty acid products now in the

solid we are we can have many

different things that means some

sometimes toys are flashed down or

sometime dollar bills are flashed down

so these things can also be collected

and that those things can be uh

separated from the Water by using this

preliminary Tre treatment now in the

preliminary treatment we uses bar

screens to screen all those huge

elements from the water so they screen

out all these things by mechanical bar

screeners now the second treatment is a

grit removal treatment now in this grit

removal treatment what they are doing

they are utilizing uh the gravitational

force and for example like fat uh or fat

materials like gree materials so they

are not water soluble they will uh be

floating on on the water if we give the

time for settling them down now what we

utilize in this case we utilize any fat

solution and we can see all those grease

which uh which uh we have collected and

which can pass us through the bar skins

can be uh coagulated in this tape and we

can have this grease balls formation

which will float and we take those

grease balls scrap off with the help of

the scum removal now we we take up all

these things with the help of scum

removal and you take and uh left them

aside and it will remove all those

Grease materials and right after that we

end up with the water and with with in

in the water we are having small

particles of other nutrient sources but

not the bigger particles because all the

bigger particles are being removed in

this bar screens and the GRE removal

system of preliminary treatment now in

this uh now right after that uh this

this enters into uh the primary

treatment in the primary treatment

basically primary treatment is

consisting of one large SC which is

called uh the primary clarifier in this

primary clarifier what we are having we

are having one Central ring and with the

help of central Ling we have two

different parts we we are having one

strand here at the top and we are having

another strand at the bottom now both of

the strands are functioning in different

ways now this this top strand which is

just moving on the surface of the water

is is collecting all those small

particulate matter which is floating on

which are floating on the water water

and uh they drag them into one side and

keep them away from the water and the

second uh uh second uh what you can say

uh the layer or second uh system which

is placed here which is also rotating

and this second uh layer or second uh

strand what we can see is uh actually

slightly uh rotating in a very very low

uh velocity and as a result of this

rotation it actually helps all the small

sediment all the small particles to

sediment in the in in the layer or the

lower region or lower tank or reserver

tank for this primary clarifier which is

called the primary sludge now I I'm

telling you this this sludge whenever

you heard this name of sludge the sludge

means the solid waste part of a

wastewater treatment in any cases there

are this waste water is consisting of

two parts as I've told you before there

the liquid part then the solid part the

solid part would be very very huge

solids which can easily be separated

using preliminary treatment like bar

screens and grit removal but in the

secondary treatment we in the primary

treatment we must remove all those small

parts we give the time for them to to be

sedimented utilizing the gravitational

force and they start to sediment onto

the bottom and as they're sedimented we

drag them away and take them in the slud

treatment process now we have we will

discuss this SL treatment later now

right after that all the P all the water

which is uh being clarified using

primary clarifier is been taken onto the

second round which is called the

secondary treatment of waste water and

this type of treatment is called the

biological treatment because in this

treatment we utilize uh the

microorganisms to purify the water or to

clarify the water now in this kind of

section there will be two different

sections one is the irration Basin and

another is will be the uh anerobic

chamber now these two things can also

happen now in airation Basin what we

what we have done we take the water from

the primary clarifier we put it onto

this Iration Basin and in this Basin we

actually vigorously air this Basin all

the time throughout the time and we

Propel a fan here and we we keep on

adding air bubbles onto it and it will

help some of the bacterias which we add

onto this water to grow and multiply

very rapidly and those bacteria will

love to eat uh those nutrients which are

being stored on onto this waste water

because this waste water is consisting

of human waste so bacteria can feed onto

it so we need to select the type of

bacteria that we are using in this

Iration Basin because those bacteria

must be aerobic type because there is a

lot of air in this case and we also

design another chamber which is not uh

seen which is not put in this picture

but that is called the anerobic chamber

inside the anerobic chamber we also put

some microorganisms but those

microorganisms are anoxic or anerobic

microorganisms which can also uptake the

nutrients but an aerobically so that's

why you give them their own room for

doing this so we set uh this water there

we put the microorganisms and the

microorganisms do the work for us for

this part and in the Iran Basin almost 5

to 6 hour we need to spend this water so

this this is a long time at this

particular point now right after uh

release from this aration Basin we have

another clarifier which is called a

secondary clarifier because this

clarifier is little bit much more bigger

and this is placed in the secondary

treatment that's why it's called a

secondary clarifier in the secondary

clarifier we we use uh we put this water

from the Iran tank or an arobic

treatment plant and then in this this

clarifier what happens as a result of

bacterial enzymatic action all those

small nutrients start to coagulate with

each other and they are going to

sediment uh they are going to form a

layer at the bottom of this secondary

clarifier as the sludge and this is

called the secondary sludge and we can

also drag this sludge for our treatment

with the help of sludge treatment

process now after that the water uh will

come from the secondary clarifier

towards the third layer of water

treatment which is called the tertiary

treatment or the chemical treatment

because in this part of the treatment we

are treating this waste water with

chemicals to get rid of uh the bacterias

or microorganisms which are left behind

because remember we utilize

microorganisms to degrade our food or

nutrient materials that's fine they do

the job for us but now it's time for

removing those microorganisms because if

they live on the water they can be

dangerous for us because those

microorganisms can be pathogenic can be

devastating for us so we need to kill

them too so we utilize all those

chemical process to kill those

microorganisms in this tertiary

treatment so we utilize all those

chlorination sometimes chlorination can

be a form of gaseous chlorine or can be

a form of liquid chlorine or sometimes

in form of tablet chlorine uh then right

after this chlorination we we we need to

uh uh control the number of or

concentration of chlorine in the water

remember sometimes when the higher

amount of chlorine come into the water

we can we can can taste it really in the

water so this is a flog of this

wastewater treatment or sometimes this

chlorine can make a damage uh to us

because chlorine is halide and any

helide is dangerous for a human body or

any is dangerous for any animal so this

chlorine which we put it is in higher

concentration or sometimes this

chlorinated water if we direct uh

directly discharge this water onto the

streams then it can damage uh our fresh

water Flora for example those fishes and

all those phytoplankton Z planton

whatever place there they can be uh

harmed by by this chlorine that's why we

need to remove the chlorine due to some

extent or we need to uh we need to take

uh the concentration of the chlorine

down to some extent we can do this by

utilizing UV disinfection or sometimes

we can just do this with the help of

another chemical treatment by utilizing

so SO2 sulfur dioxide is a very

important key player in this case so we

add sulfur dioxide right after the

addition of uh the treatment by sulfur

dioxide or UV disinfection our water is

totally pure and it is ready to be

discharged in the Stream again so that

is how the liquid part of the waste

water is travel from preliminary

treatment which is the mechanical

treatment so this is the mechanical

treatment and then we go to the primary

treatment which is also a mechanical

treatment so preliminary and primary are

the mechanical treatment then you go to

the secondary treatment which is a

biological treatment through which

finally we end up with the chemical

treatment which is the tertiary

treatment and finally we release the

water onto the stream where we have

taken all this water from okay so that's

how it's work now let us talk about the

slge treatment process now uh what is

the SL treatment M as we have told

before in the primary clarifier and in

the secondary clarifier we have we have

sedimented out fewer uh not few many

amount of all those solid materials

which are being stored in this waste

water for so long now these nutrients

are dangerous those are toxic but if we

if we utilize them properly if we

process them properly then they might

end up with some very very interesting

and very very uh economic product which

we can utilize in the soil as a soil

conditioner so that is a very important

concept so we take up all those slud

from the primary clarifier as well as

from the secondary clarifier and we take

and we we go through the sludge

treatment process now in any slud

treatment process there are three

different parts one is the sludge

digestion then is uh the sludge uh

thickening and then is the sludge

dewatering so these three part parts are

really important during any sled

treatment process so what we have seen

in this case we utilize we take the

sludge we digest the sludge now what do

we mean by the sludge digestion it means

that we we are having a huge pipes and

pumps are there we utilize heat we

utilize few amount of bacteria which are

present on the sludge to digest the

sludge anaerobically and as a result of

this anerobic digestion of the sludge

they produces methane gases now in this

particular process we can utilize fewer

amount of microorganisms which are

methanogens now we know that action of

methanogens that they can utilize carbon

sources and generate methane gas now the

methanogens can act on this sludge they

can produce methane gas and as a result

of they produce this methane gas as you

can see in this case this methane gas uh

is a very good fuel as we know so we can

utilize the energy which is stored in

this methane gas to run few generators

and few pumps in the same wastewater

treatment plant so it's a circulation of

energy in the wastewater treatment plant

so it is a pretty good for us to utilize

this kind of uh sludge digestion and the

energy which is derived from the sludge

digestion right after this sludge

digestion we we

utilizes the sludge thickener to thick

uh to make the sludge thicken so how can

thick make make sludge thicken so we we

utilizes sludge thickers and in the

sludge thickeners usually there are

different types of sludge thickers like

uh gravitational force gradient

dependent and all these different types

so there are SL ther common type of

Slash ther that are used are called DS

or okay it is called dissolved air flow

type of Slash thicker now this type of

Slash thickner what they are doing they

are actually uh inside a huge chamber

they uh push the air onto the sludge in

very high pressure and then just release

the pressure so that this sludge will

float onto the top and the watery part

remains on the bottom now as a result of

this uh this process we can have really

solid and thick sludge now right after

this made up this sludge thickening we

we have to dry the slud why because in

this particular step or after the

particular step what we end up with we

end up with a pretty thick sludge which

is having almost most of the sludge

components but uh it is uh still

containing very uh moderate amount of

water so we need to dewater it before

utilizing it for the soil conditioning

purpose otherwise those watery part are

pretty uh pretty problem pretty problem

creating for handling and all these

things so we need to make them dry so uh

this drying will help us in different

ways of transport and or or Market uh

marketing or placing them so for that

purpose we need to dry them a little bit

so we we them we dry them we dewater

them utilizing the chambers denoting

here these Chambers are called

centrifuges and we know in scientific

Labs we have used centrifuges and those

centrifuges are small there those are

micro centrifuges but these centrifuges

which are used in this case of slud

dewatering uh these are really really

huge and mega centrifuges and in this

centrifuge the mechanism is remaining

the same so it is sedimented at the

bottom and the water uh is uh placed at

the top and the sludge is sedimented at

the bottom so it's a layer of sludge at

the bottom we just take out this sludge

from this

place and the sludge becomes a solid

cake like structure we we take this

ludge we put it on the van we we take it

onto the Landfield and we dump it there

and this ludge is containing very very

important nutrients and ingredients

which will help to nourish the soil for

a long time so that's why uh this L

treatment is done in this way so this is

the overall wastewater treatment process

so remember wastewater treatment process

is conducted in two different ways one

is the watery part dealing second one is

the solid part dealing in the watery

part dealing we are having four

different sections one is called the

preliminary then primary then secondary

and the tertiary treatment in the

primary and uh preliminary treatment are

mechanical treatments utilizing the

mechanical process to separate out

solids and in the secondary treatment we

utilizes biological system like

microorganisms to treat the water and in

the tertiary treatment we utilizes

chemical uh things to actually take out

all those necessary uh bad things from

the water okay and

and also in the chemical treatment

sometimes utilizes aluminium chloride

and all these type of salts to actually

settle down some of the solid particles

or some of the phosphorus particles who

still uh there in this water but but

most of the nitrogenous compound and

phosphorus particles are gone right

after the secondary treatment so if we

if you uh if somebody tells you which is

the most important part uh of this

system you must say this is the

biological part of the secondary

treatment part which is the most

important because in this part almost

everything is treated except for fewer

uh fewer consideration like odor

sometimes few amount of phosphorus

dissolved phosphorus and sometimes uh

and those bacterias which are added

right except for this the water is

almost ready to be discharged onto the

onto the water stream right so that's

why it's important now in the second

part we are having the slash treatment

process in the slash treatment process

we go through three different steps one

is the slash digestion we in this case

we utilize the energy from the SL dig to

run out a few pumps and generators in

our wastewater treatment plant that's a

very important part and then we are

having thickener and also we are having

those dewatering part so these are the

steps of w waterer treatment plant and I

hope it will help you to understand what

it is thank you