With the incineration of sewage sludge, more than 80 percent of the phosphorus resource contained in sewage sludge can be recycled.
“Sewage sludge is so much more than waste.”
“Sewage sludge is more than waste. Energy can be generated and it can be used as a basis for a new raw material, especially for fertilizing.
It’s a circular economy at its finest,” Weil said. The construction of the plant is therefore also an important step in the transformation of energy production. Energy is no longer obtained from coal, but from sewage sludge and corresponding alternatives.
Sewage sludge is an important source of raw materials for agriculture. The phosphorus it contains is used, among other things, to produce fertilizers. So far, sewage sludge has either been applied to agricultural land or burned in coal-fired power plants.
However, pollutants contained in the sludge also get onto the fields.
Greentech sewage sludge plant generates energy and phosphorus Photo: MVV
If sewage sludge is incinerated, the valuable phosphorus is lost
If sewage sludge is incinerated in coal-fired power plants or waste incineration plants, the pollutants it contains are destroyed, but the valuable phosphorus is also irretrievably lost, as it can no longer be recovered from the ash. In a downstream process in the mono-incineration plant, the phosphorus will then be recycled after the sewage sludge has been incinerated.
An amendment to the Sewage Sludge Ordinance passed in 2017 provides for reducing the agricultural use of sewage sludge and ensuring phosphorus recovery from 2029. With the new plant, less nitrate and pollutants are now supposed to get into the soil and groundwater.
Less nitrate and pollutants on soil and in groundwater
“If we succeed in achieving the 80 percent phosphorus recovery required by law, up to 40,000 tons of phosphate recyclates would be available in Germany for fertilizer production every year,” said the CEO of the operator EEW, Timo Poppe. In Helmstedt, 15,000 tons of phosphate-containing ash would be recovered for recycling each year, Poppe said.
According to EEW, the sewage sludge incineration plant is able to utilize around 20 percent of the sewage sludge produced in Lower Saxony every year. About 160,000 tons of dry sewage sludge are to be incinerated in the plant. Around 5,000 households are to benefit from the excess energy generated and be supplied with electricity.
Greentech sewage sludge can generate energy and be the basis for new raw materials
Around 130,000 tons of dewatered sewage sludge are to be recycled in the mono-incineration plant recently opened in Hanover. The resulting excess energy is to be fed into the district heating network and supply around 5,000 households with climate-neutral district heating. In Hanover, too, the phosphorus is to be recovered after the sewage sludge has been incinerated.
According to the consulting firm Ecoprog, more than 30 sewage sludge mono-incineration plants are currently in operation in Germany. More than 50 projects for the construction of additional mono-incineration plants are being planned.