Water quality – Wastewater treatment standards in different countries
In most developed countries, standards for wastewater treatment are continuously improving. Compared to the 1970s the effluent requirements for the most important pollutant indicators BOD, Nitrates and Phosphorus have steadily increased. For example, in the United states the clean water act from 1972 demands that all Municipal sewage treatment plants (POTW) are required to meet […]
TKN tutorial – What is the difference of ammonia and ammonium
Johan Kjeldahl developed in 1883 a method for the quantitative determination of nitrogen contained in organic substances and inorganic substances – ammonia NH3 and ammonium NH4+. He named the sum of all measured nitrogen TKN – total kjeldahl nitrogen. TKN plus Nitrate Nitrogen (NO3-), Nitrite Nitrogen (NO2-) and Nitrogen gas (N2) can be summarized in […]
How do tube settler work – plate settler, lamella clarifier tutorial
Tube settlers which are also known as plate settlers or lamella clarifiers are used to increase settling performance within a sedimentation basin. Tube settlers consist of inclined plates or channels that provide a settling surface area for particles in wastewater and drinking water. The total settling area is the sum of the projected area in […]
Oxygen transfer rate in Wastewater treatment – calculation example
Before we can calculate the oxygen transfer rate, we have to determine our oxygen demand. Depending on the wastewater treatment target different factors must be considered to calculate the actual oxygen requirement (AOR). Design flows and loads: Water influents are not consistent and vary between daily minimum, average and peak flows. Design guidelines recommend dividing […]
Surface aerators and submersible aeration equipment for wastewater treatment
The activated sludge process requires certain types of microorganisms to break down organic matter in wastewater. As any other living organism, the microorganisms need energy to reproduce. When breaking down organic matter or oxidizing ammonium (NH4+) to Nitrite (NO2-) energy in the form of ATP for microorganism reproduction is released. However, both conversions need oxygen. […]
Tube settler self-assembly kit – easy assembly on site
All tube settler module designs for particle separation have one thing in common: Assembled blocks consist to more than 90% of air. Therefore, depending on the distance between place of fabrication and place of installation, freight costs can be a big cost factor. For example a 54ft truck has a loading capacity of about 3,500ft3. […]
Lamella clarifier guideline – tube settler design and CFD simulation (Video animation)
Apart from the selection of the right lamella clarifier module the design of lamella clarifier tanks requires several design considerations. More details on the selection of the right lamella clarifier module can be found in the linked video. Other parts of a lamella clarifier tank are the water inlet, sludge settling and water outlet zone. […]
Activated sludge process – Upgrade with IFAS
After explaining how the activated sludge process works in part 1 we are now taking a closer look on how to increase the wastewater treatment capacity of ASP with IFAS systems. IFAS stands for integrated fixed film activated sludge and describes the combination of fill media attached growth systems with the activated sludge process. The […]
Flocculation and coagulation – How to form particle flocs and settle them down
Flocculation and coagulation are fundamental for wastewater treatment and were already used by the ancient Egyptians in 1,300 BC. This sample of muddy looking water from a paper mill has a very high turbidity due to the presence of many suspended particles. Adding flocculants will cause that small particles clump together to bigger flocs that […]
History of wastewater treatment – from Hippocratic sleeve to activated sludge
Nowadays wastewater treatment plants are large, complex facilities that use multiple technologies to remove up to 99% of all pollutants in wastewater. Our standards for clean water are continuously rising and not one day passes by without new innovations for wastewater treatment. But wastewater treatment was not always this advanced. So, let’s have a look […]