Sludge Treatment

SLUDGE TREATMENT
Sewage Sludge - product ng municipal waste water treatment.
THE PRACTICAL AND TECHNICAL CHALLENGES OF SLUDGE

HANDLING ARE:
1. Stabilising - sludge is not inert and can have an unpleasant odour

2. Bawasan ung water content tapos ung volume to the minimum.
3. Bawasan ung harmful micro- organisms if people, animals or plants are in
contact with the sludge
4. Recovering phosphorus for agriculture.
Sewage sludge treatment is more than only thickening, digestion,

dewatering and disposal. It has consequences for the whole treatment
plant.
1. retention time sa primary sedimentation ay may effect sa biogas production. A

higher Retention time decreases the BOD load in biological treatment. This
decreases the denitrification capacity and may require an additional carbon
source. Other possible effects are better dewaterability and lower disposal
costs.
2. Biological phosphorus removal reduces the dewaterability up to 10%.
SLUDGE THICKENING
 Yung water na lumalabas sa Wastewater has a water content of between
97% and 99.5.
 In sludge thickening, dry solids content of sludge is increased by
reducing the water content with low energy input.
 Sludge thickening can be applied both as a pre-treatment for digestion as
well as a pre-treatment for dewatering in WW treatment plants that
operate without digestion.
GRAVITY THICKENING
- is the easiest way to reduce the water content of sewage sludge, low
energy consumption lang ung ginagamit.
- Sludge is pumped directly to a circular tank equipped with a slowly
rotating rake mechanism, which breaks the junction between the sludge
particles and therefore increases settling and compaction.
 Gravity Thickening, reduce the sludge volume to 90% from the original
volume.
 Gravity thickening consumes very little energy.
2- 3% and 3-4%
MECHANICAL THICKENING
- usually used for thickening excess sludge. Mixture of sludges is often
thickened mechanically at plants with a small primary sedimentation unit
or when the sludge is not treated in the digestion process.
o Mechanical thickening needs flocculant aid and electrical energy, and
can be operating continuously.
o Mechanical thickening equipment options include screw, drum and
centrifuge.
STABILISATION
- The aim of stabilisation is the reduction of biological and chemical
reactions to a minimum.
- Anaerobic digestion is one of the oldest and still most commonly used
processes for sludge stabilization.
- Concentrated organic and inorganic sludge matter is decomposed
microbiologically in the abscence of oxygen and converted to methane
and inorganic end products.
- Ang makukuha sa digestion are the stabilized sewage sludge, volume
reduction and biogas production.
- Anaerobic Digestion process is operated either in mesophilic (around
35-40 degree Celcius) or thermophilic (53- 57 degree Celcius)
temperature ranges.
- They are using thermophilic but no success mas better ang mesophilic
temperature.
- Advantage ng mesophilic ay good process stability and supernatant
quality with reliable operation experience.
- Possible na mareduce ung sludge volume and gain biogas for energy
supply.
- It produces a significant amount of reject water that increases the
nitrogen and COD loads in WW treatment plant.
- Ung anaerobic digestion sinasanitize ung sludge to make it safe

spreading to land and provide a fertilizer called digestate.
- Ung digestion takes place in one or several reactors, which can be fed
paralled or in a row with a typical retention time of between 20 and 25
days.
- Minimum retention time is around 14 to 15 days (lower retention time
normally binabawasan ung gas production, some treatment plants are
operating less than 14 days without any reduction of gas production.
Primary sludge is easier to digest and easier to dewater compared to
excess sludge that consists of bacteria from activated sludge process.
- The digestion of excess sludge requires a longer detention time.

- A mixture of primary sludge and excess sludges should reach a dry
solid content of between 4-7% before digestion.
- Increasing the DS content causes lower energy consumption for
heating and a reduced digestion time.
- The digestion reactor is always equipped with a mixing and a heating

device for good mixing and constant temperatures.
- pag ung temperature varies less biogas ung mapproduce.
- Kelangan haluin ung digester mas better.
- pag na degrade ung sludge to 50% means good performance.
PRODUCE GASSES SUCH AS

1. Methane (58- 64%)
2. CO2 (30-40%)
3. Hydrogen Sulfide
CHP - Combined heat and powerplant.
SLUDGE DEWATERING
- this process is simple, increasing the DS content of sludge with
different types of equipment.
- The unit process always requires the use of at least some flocculant aid
that keeps the excess sludge flocculated in the dewatering unit.
Sometimes coagulation chemicals such as iron or aluminum salts are also

added in order to enhance the efficiency of flocculant aids (polymers) and
reduce the consumption of them in sludge dewatering.
- After dewatering, the DS content of the sludge is usually between 19%
and 30%. Depending on the dewaterability, it is possible to reach a dry
solid content of 40%.
- Centrifuge and Belt Filter Presses are currently the most popular
dewatering methods in municipal WW treatment plants due to their good
operation and cost efficiency.
DECANTER CENTRIFUGE
- The key elements in centrifuge are the bowl, which includes cylindrical
and conical sections, the conveyor screw inside the bowl and the drive
units rotate them.
- The casing surrounding the bowl acts as a protective noise
suppression barrier, and the channels the dewatered sludge cake and
separated clarified liquid - or centrate - out from the unit.
BELT FILTER PRESS

- The key elements of a belt filter press are the frame that supports the
integrated sludge feed, the upper and lower belt systems for gravity
drainage and pressing, the belt guidance and wash systems and the sludge
discharge.
-Modern models often include an integrated enclosure to suppress the
splashing of sludge and filtrate and the release of vapour, mist and
malodorous gases.
CHAMBER FILTER PRESS

- consists of a series of filter chambers containing filter plates supported
in a frame.
- The sludge is fed in a batch manner then loaded filter chambers are
forced together with hydraulic rams. The sludge is squeezed in few
seconds by up to 60 bar pressure in the press.
The dewatered sludge is then discharged from chambers by opening the
filter plate and shaking cloth or plate.
The chambers and filter cloth are washed regularly to ensure continuous
good filtration results and a longer durability of the cloths.
- Improved version of the chamber filter press is the membrane filter
press, which reaches a DS content that 2-3% higher due to an additional
membrane between the filter cloth and the filter plate.

Sludge Treatment

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SLUDGE TREATMENT

Sewage Sludge - product ng municipal waste water treatment.

THE PRACTICAL AND TECHNICAL CHALLENGES OF SLUDGE

1. Stabilising - sludge is not inert and can have an unpleasant odour

Sewage sludge treatment is more than only thickening, digestion,

1. retention time sa primary sedimentation ay may effect sa biogas production. A

- Ung anaerobic digestion sinasanitize ung sludge to make it safe

- The digestion of excess sludge requires a longer detention time.

- The digestion reactor is always equipped with a mixing and a heating

PRODUCE GASSES SUCH AS

CHP - Combined heat and powerplant.

Sometimes coagulation chemicals such as iron or aluminum salts are also

BELT FILTER PRESS

CHAMBER FILTER PRESS

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