Sewage treatment

Sewage treatment processes include A2O process, oxidation ditch process, Sequencing Batch Reactor (SBR) process, and some derivative modified process forms. In addition, biological membrane processes such as Biological Aerated Filter (BAF) are also applied in secondary treatment or advanced treatment of sewage.

Monitoring Parameter

pH Value

ORP (Oxidation-Reduction Potential)

Dissolved Oxygen (DO)

Application Description

The pH value is crucial in the biochemical treatment of sewage and wastewater because microorganisms can only maintain maximum activity within a specific pH range, making pH the most basic monitoring indicator in biochemical treatment. Additionally, in chemical treatment methods such as neutralization and coagulation, pH detection is required to ensure reactions occur under optimal conditions for the highest possible reaction efficiency.

Product Selection

AL4030 Digital pH Sensor

Suspended Solids/Sludge Concentration

COD (Chemical Oxygen Demand)

During wastewater treatment, oxidation-reduction potential is particularly important in anaerobic treatment processes. The anaerobic environment must not only be free of dissolved oxygen but also exhibit overall reducing properties, characterized by an ORP value less than 0. For anaerobic tanks in municipal sewage biological treatment, the ORP typically needs to be below -100mV.

In aerobic biological wastewater treatment processes, dissolved oxygen is one of the most critical monitoring indicators. Aerobic biological treatment requires a certain concentration of DO to maintain the activity of aerobic bacteria, enabling them to absorb and degrade organic matter. In aerobic activated sludge processes, DO in the aeration tank usually needs to be maintained at around 2mg/L or higher to ensure the removal of organic pollutants and ammonia nitrogen. In Biological Aerated Filter (BAF) processes, DO should be kept at 3-4mg/L.

Suspended solids (SS) are one of the most basic water quality indicators for wastewater, representing the amount of insoluble solids per liter of water, including inorganic and organic substances, sand, clay, microorganisms, etc., that do not dissolve in water. SS is an indicator for measuring water pollution degree and the main cause of water turbidity. Sewage discharge standards specify the maximum allowable concentration of SS.

BOD5 is a common indicator for analyzing organic pollutant concentration in urban sewage treatment, but due to its long testing time, COD is often used as a supplement or substitute.

AL4100 Digital ORP Sensor

AL4050 Digital Dissolved Oxygen Sensor

AL4140 Suspended Solids and Sludge Concentration On-line Sensor

AL4010 UV-COD On-line Analyzer

The on-line water quality monitoring requirements for sewage treatment include:

Ammonia Nitrogen

In sewage, only a small part of ammonia nitrogen is used by bacteria for cell synthesis, while most is removed through aeration, where it is converted to nitrate nitrogen by nitrosifying and nitrifying bacteria. Process monitoring of ammonia nitrogen optimizes treatment process operation.

Nitrate Nitrogen

Nitrate nitrogen is a stable nitrogen-containing compound in anaerobic environments and the final decomposition product of nitrogen-containing organic compounds after inorganicization. After the aerobic stage of sewage treatment, ammonia nitrogen is converted to nitrate nitrogen, which must be transformed into nitrogen gas through anoxic denitrification to achieve true nitrogen removal. Monitoring nitrate nitrogen during the anoxic process optimizes operation and enables real-time control of denitrification.

Total Nitrogen (TN)

Nitrogen in sewage exists as organic nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen, with their sum being total nitrogen (TN). Treated sewage must meet not only ammonia nitrogen discharge standards but also TN requirements.

Orthophosphate

In sewage treatment processes, while part of the phosphorus is used by bacteria for cell synthesis, the remaining phosphorus needs to be removed by methods like chemical dosing. Process monitoring of orthophosphate enables real-time control of chemical dosage, ensuring effluent quality compliance while optimizing chemical usage.

AL4070 Ammonia Nitrogen On-line Analyzer

AL4080 Nitrate Nitrogen On-line Analyzer
AL4020 Spectroscopic On-line Water Quality Analyzer

AL4020 Spectroscopic On-line Water Quality Analyzer (for TN monitoring)

AL4020 Spectroscopic On-line Water Quality Analyzer
Specialized orthophosphate online sensor (if available, such as AL series orthophosphate analyzer)