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Waste Water Treatment
Transcript of Waste Water Treatment
-consists of applying known technology to improve or upgrade the quality of a wastewater.
- Usually involves collecting the wastewater in a central, segregated location (the Wastewater Treatment Plant) and subjecting the wastewater to various treatment processes.
-A complete treatment system may consist of the application of a number of physical, chemical and biological processes to the wastewater.
-include processes where no gross chemical or biological changes are carried out and strictly physical phenomena are used to improve or treat the waste water.
- is a very common process operation and is routinely employed at the beginning and end of wastewater treatment operations.
- physical phenomena relating to the settling of solids by gravity are allowed to operate.
- consists of simply holding a wastewater for a short period of time in a tank , allowing the heavier solids to settle, and removing the "clarified" effluent.
- physically adding air, usually to provide oxygen to the wastewater.
- waste water is passed through a filter medium to separate solid
the use of sand filters to further remove entr
ained solids from a treated waste water.
Flotation and Skimming
- Wastes are sometimes held, mixed with other wastewaters, and gradually released, thus eliminating "shocks" to the treatment plant.
- can be used to even out wide variations in flow rates.
- consists of using some chemical reaction
or reactions to improve the water quality
Chemical Treatment Methods
- most commonly used chemical process
- Chlorine, a strong oxidizing chemical, is used to kill bacteria and to slow down the rate of decomposition of the wastewater.
- Bacterial kill is achieved when vital biological processes are affected by the chlorine.
- ozone is another strong oxidizing agent that has also been used as an oxidizing disinfectant
-consists of the addition of acid or base to adjust pH levels back to neutrality.
- Since lime is a base it is sometimes used in the neutralization of acid wastes.
- consists of the addition of a chemical that, through a chemical reaction, forms an insoluble end product that serves to remove substances from the wastewater.
- Polyvalent metals
- iron containing compounds (such as ferric chloride or ferric sulfate)
- alum (aluminum sulfate).
- involves exchanging certain ions for others - are not used to any great extent in waste water treatment.
Use of activated carbon to "adsorb" or remove organics.
mostly bacteria, in the biochemical decomposition of wastewaters to stable end products.
-Activated Sludge Treatment Methods -Trickling Filtration
- Aerobic Digestion
- Anaerobic Digestion
- Septic Tanks
- done to protect the operation of the wastewater treatment plant.
- This is achieved by removing from the wastewater any constituents which may clog or damage pumps, or interfere with subsequent treatment processes.
The preliminary treatment devices used are designed to:
1. Remove or to reduce in size the large, entrained, suspended or floating solids. These solids consist of pieces of wood, cloth, paper, plastics, garbage, etc. together with some fecal matter.
2. Remove grits (heavy inorganic solids such as sand and gravel as well as metal or glass).
3. Remove excessive amounts of oils or greases.
Devices that are used
for Preliminary Treatment
- These consist of bars usually spaced three-quarter inches to six inches.
- Can be set vertically or inclined in 45 or 60 degrees.
Racks and Bar Screens
Grinders, cutters and shredders
These are devices that breaks and cuts up solids to such size that they can be returned to the wastewater without danger of clogging pumps or piping or affecting subsequent treatment devices.
Waste water usually contains a relatively large amount of inorganic solids such as sand, cinders and gravel which are collectively called grit. Grit will damage pumps by abrasion and cause serious operation difficulties in sedimentation tanks and sludge digesters by accumulation around and plugging of outlets and pump suctions. This grit is removed by grit chambers
removing organic and inorganic solids by the physical processes of sedimentation and floatation is by the
Parts of Settling Tanks:
-Septic tanks - tank itself
-Two story tanks
-Plain sedimentation tank with mechanical sludge removal
-Upward flow clarifiers with mechanical sludge removal
-designed to substantially degrade the biological content of the sewage
-depends primarily upon aerobic organisms which biochemically decompose the organic solids to inorganic or stable organic solids
-consists of the biological treatment of wastewater by utilizing many different types of microorganisms.
The devices used in secondary treatment may be divided into four groups:
1.Trickling filters- microorganisms are attached to a fixed surface forming a biological film
2.Activated sludge and modifications with final settling tanks- microorganisms are dispersed throughout the water phase
3. sand filters
(Advanced waste water treatment)
Types of advanced wastewater treatment
it is a treatment similar to secondary treatment.
The main difference is that some operations are added to the flow. It can be addition of suspended solids removal or much complex organic, nitrogen and phosphorous removal.
it is a treatment where biological and physical-chemical processes are incorporated to achieve the effluent wanted.
it is different from tertiary treatment since this combined treatment mix biological and physical-chemical are mixed rather that simply added after the basic biological treatment.
Another basis in classifying advanced wastewater treatment is by their goals. It is used for:
1. Additional organic and suspended solids removal
2. Removal of nitrogenous oxygen demand (NOD)
3. Nutrient removal
4. Removal of toxic materials
Why do we have to undergo
1.Advanced wastewater treatment plant effluents may be recycled directly or indirectly to increase the
available domestic water supply.
2.Advanced waste water treatment effluents may be used for industrial process or cooling water supplies.
3.Some receiving waters are not capable of withstanding the pollutional
loads from the discharge of secondary effluents.
4. Secondary treatment does not remove as much of the organic pollution in wastewater as may be assumed.
this can prevent the depletion of oxygen from nitrogenous demand. It is simply the conversion of ammonia to nitrate.
it is the removal of nitrogen as nitrification satisfies nitrogenous oxygen demand
filtration is the process where you remove the suspended and colloidal solids that are accumulated from other unit processes. It is a common process in advanced wastewater treatment.
Advanced wastewater treatment can be used depending on the desired level of treatment. This uses complex processes and equipment that is why it is expensive to run and operate.
EXAMPLE (Ginebra SAN MIGUEL, Inc):
Wastewater Treatment Process of GSMI DBI Distillery:
2.Cooling Spray Pond
3.Holding / Neutralizing Tank
5.Up-Flow Anaerobic Sludge Blanket (UASB) Reactors
6.Primary Aeration Basin
8.Secondary Aeration Pond
10.Wetland and Aquatic Plant Pond
Luis Caeg, Jeremy Enriquez
Marvin Lim, Ivan Samaniego
1. Primary Treatment
Waste water flows into the primary chamber. Initial settlement and
floatation of solids occur. The liquid effluent passes forward for treatment through the tube located at the middle of the tank.
2. Secondary Treatment
From the primary treatment zone the separated liquid now enters the secondary treatment zone.The micro organisms consume those organic pollutants reducing the levels of BOD (Biological Oxygen Demand)