Sludge is the byproduct of wastewater treatment that normally contains organic matter from human waste, inorganic solids, trace chemicals, together with water bound to these materials.

1. Sludge treatment and
waste disposal
services that leave
minimal impact on the
environment

2. INTRODUCTION
Sludge is the byproduct of wastewater treatment that
normally contains organic matter from human waste,
inorganic solids, trace chemicals, together with water bound
to these materials. Sludge can come from domestic waste,
commercial waste, and industrial waste. Industrial sludge is a
byproduct of specific factory processes, such as food
manufacturing, pulp and paper factories, pharmaceuticals,
etc. Certain types of sludge are allowed to enter municipal
sewer network while other types of industrial sludge are
required to be delivered to a sludge treatment plant to be
mixed with sewage sludge for treatment.

3. Today, instead of simply being a waste, sludge is increasingly being
seen as a resource. Through a sludge treatment process, known as
anaerobic digestion, a waste disposal service can recover biogas from it
and also convert bio solids in it into a nutrient-rich soil product. Some
waste disposal services can also recover valuable sludge minerals from
it, such as phosphorous, which is a non-renewable resource.
Sludge treatment becomes necessary because wastewater cannot be
treated until solids or sludge are removed from it. Once sludge is
treated, it should not be disposed of in its raw form by waste disposal
services as it can potentially contaminate the natural environment.

4. Sludge treatment depends on the
amount of solids present in it, and
other specific conditions at the waste
disposal services. After any
treatment, sludge is usually referred
to as bio solids which are usually
applied on land, incinerated, or
deposited into landfills. Digestion is
one of the most common methods
used by professional waste disposal
services, such as Solo Resource
Recovery, that includes below steps.

5. THICKENING
This low-energy step by the waste
disposal services is used to separate
water from the solid components of
sludge before the process of anaerobic
digestion starts. Sludge thickening
reduces the overall sludge volume and
increases the proportion of solids in the
sludge. Gravity thickening is often used to
settle the sludge’s solid portion. Other
thickening methods used by the sludge
treatment company include centrifugal
thickening, dissolved air floatation, and
rotary drum thickening. Sludge thickening
can get from 2% to 18% solids by weight.

6. Sludge digestion can either be aerobic (with oxygen), and anaerobic (without
oxygen). Anaerobic digestion (AD) is often more cost-effective, and that’s why this
method is more commonly used in sludge treatment. The process uses an elevated
temperature and naturally occurring microorganisms in sludge to break down and
ferment them. This slow process takes place in large, airtight tanks at the sludge
treatment facility.
Anaerobic digestion has four biological steps:
Hydrolysis
Acidogenesis
Acetogenesis, and
Methanogenesis
These sludge treatment steps transform the sugars and complex proteins in the
sludge into carbon dioxide, water, and methane. The biogas produced from these
steps, which largely contains methane and carbon dioxide, is collected and used as
fuel for producing heat and generating electricity.
Digestion:

7. DRY HEATING AND INCINERATION
Some more sludge treatment methods can also be used in combination with digestion.
Alkaline stabilization is a widespread sludge treatment process wherein bio solids are either
recycled or reused. Thermal drying is used to increase the dry solids (DS) content of the sludge.
Some waste disposal services also use thermochemical treatment procedure viz. Incineration.
In incineration, the sludge is burned at a temperature of 650 degrees Celsius. In heat drying, a
furnace is used to heat dry sludge at a temperature of 350-degree Celsius, to reduce the
moisture content from the sludge that is released in the form of gas. The produced gas can be
used to maintain wastewater treatment plants.
Biosolids dewatering: Belt filter presses (BFP) and centrifuges are common dewatering
technologies used by waste disposal services. Depending upon the type of raw sludge, BFP can
increase dry solids from 15% to 30%, or even more. Centrifuges push more solid content of
sludge to the walls of a rotating vessel wherefrom the water is collected separately. The
separated water is usually returned to the inlet of the wastewater treatment facility. In some
cases, it is required to undergo special treatments, known as liquor treatment. While
thickening only removes some of the free water in sludge, dewatering removes water bound
to the actual solids, and for this, chemical processes involving the use of polymers can be
performed.

8. AGRICULTURAL LAND APPLICATION OF SLUDGE
Once sludge is treated, it can be used in land applications as soil fertilizers
or soil amendments. It can also be used for sanitary landfilling and
placement in areas that are usually away from residences. Land application
of sludge on agricultural or non-agricultural land is considered a beneficial
reuse of the treated sludge, while other methods are simply considered
disposal methods.
As a trusted waste disposal service with over 90 years of experience, Solo
Resource Recover provides a one-stop solution for a variety of waste
disposal needs by businesses, councils, and residences in Australia. Waste
disposal services offered by Solo Resource Recovery include bulk bin
services, business waste solutions, construction waste services, council
waste services, vacuum excavation, vacuum loading, and more.

9. Thanks!
Do you have any questions?
INFO@SOLO.COM.AU
0266747656
www.solo.com.au