What is the Secondary Treatment of Sewage Water?
Secondary wastewater treatment works on a deeper level than primary treatment and is intended to significantly degrade the biological component of the wastewater through aerobic biological processes.
What is the goal of secondary wastewater treatment systems?
The goal of secondary treatment is to treat the effluent from primary treatment further to remove residual organics and suspended particles. Secondary treatment is usually performed after primary treatment and comprises the removal of biodegradable dissolved and colloidal organic materials by aerobic biological treatment techniques.
Aerobic biological treatment is carried out in the presence of oxygen by aerobic microorganisms (mostly bacteria) that digest the organic stuff in the wastewater, resulting in additional microorganisms and inorganic end-products (principally CO2, NH3, and H2O).For secondary treatment, many aerobic biological methods are utilized, which differ principally in the way oxygen is provided to microorganisms and the pace at which organisms digest organic materials.
When opposed to low-rate biological processes, high-rate biological processes have smaller reactor sizes and higher microbe densities. As a result of the well-controlled environment, the development rate of new organisms is substantially faster in high-rate systems. To generate clear secondary effluent, the microorganisms must be removed from the treated wastewater using sedimentation.
Secondary treatment sedimentation tanks, also known as secondary clarifiers, work in the same general way as the main clarifiers.Secondary or biological sludge is the biological materials extracted during secondary sedimentation that are generally mixed with main sludge for sludge processing.
Secondary wastewater treatment provides for safer discharge into the local environment by lowering typical biodegradable pollutants to acceptable levels.
The operation of secondary wastewater treatment
Secondary wastewater treatment uses oxidation to further cleanse wastewater. This can be accomplished in one of three ways:
1: Biofiltration
To guarantee that more debris is removed from wastewater, this form of secondary treatment includes sand filters, contact filters, or trickling filters. Trickling filters are often the most successful of the three filters for small-batch wastewater treatment.
2: Aeration
Aeration is a lengthy but effective procedure that involves mixing wastewater with a microbial solution. To assure results, the final mixture is aerated for up to 30 hours at a time.
3: Ponds for Oxidation
In warmer climates, oxidation ponds are commonly employed. Furthermore, this strategy makes use of natural bodies of water such as lagoons. Wastewater is allowed to flow through this body for a length of time before being stored for two to three weeks.
Quality parameter (mg/I) |
Secondary Treatment Process |
||||
Trickling filters |
Activated sludge |
||||
Input |
Output |
Input |
Output |
||
Biochemical oxygen demand, BOD5 |
21 |
8 |
- |
11 |
|
Chemical oxygen demand |
- |
- |
27 |
- |
|
Suspended solids |
18 |
26 |
- |
13 |
|
Total nitrogen |
- |
- |
- |
- |
|
NH3-N |
25 |
11 |
10 |
1.4 |
|
NO3-N |
0.7 |
19 |
8 |
5 |
|
Org-N |
- |
- |
1.7 |
- |
|
Total phosphorus |
- |
- |
12.5 |
- |
|
Ortho-P |
- |
- |
3.4 |
- |
|
pH (unit) |
- |
- |
- |
7.6 |
|
Cations: |
|||||
Ca |
43 |
55 |
41 |
82 |
|
Mg |
12 |
18 |
18 |
33 |
|
Na |
83 |
102 |
94 |
- |
|
K |
17 |
20 |
11 |
- |
|
Anions: |
|||||
HCO3 |
293 |
192 |
165 |
- |
|
SO4 |
85 |
143 |
66 |
192 |
|
Cl |
81 |
90 |
121 |
245 |
|
Electrical conductivity dS/m |
- |
- |
- |
1.39 |
|
Total dissolved solids |
476 |
591 |
484 |
940 |
|
Sodium adsorption ratio |
2.9 |
3.1 |
3.9 |
3.7 |
|
Boron (B) |
0.7 |
0.6 |
0.6 |
0.7 |
|
Alkalinity (CaCO3) |
- |
- |
- |
226 |
|
Total Hardness (CaCO3) |
156 |
200 |
175 |
265 |
What services do we provide?
Netsol Water is a large water and wastewater treatment company in India that manufactures WTP, WWTP, STP, ETP, Industrial & Commercial RO Plants, among other services. It has become our job to rescue the earth. The firm manufactures equipment’s and is dedicated to offering practical solutions that enable businesses to thrive.