Treatment of unpleasant odors at sewerage pumping stations in St. Petersburg
The system of air cleaning from unpleasant admixtures was introduced at Vasileostrovskaya sewerage pumping station to reduce the amount of bad-smelling substances at the water disposal system facilities located within the city built-up area.
Solution to which problem
Problems with odor from water disposal facilities located within the city boundaries (block sewerage pump stations, yard wells, tunnel manifold shafts) appear due to reduced water consumption. As a consequence, sewage water motion speed is reduced, which gives rise to sludge deposits in sewer manifolds with their subsequent fermentation and exudation of unpleasantly smelling substances.
To solve the problem and reduce bad-smelling substances at the water disposal system facilities located within the city built-up area, a system of air cleaning from unpleasant admixtures was introduced at Vasileostrovskaya sewerage pump station (VOPS).
The gas cleaning systems implement three-stage exhaust gas cleaning:
- mechanical cleaning from finely dispersed admixtures;
- adsorption cleaning from hydrogen sulfide;
- adsorption cleaning from volatile organic compounds.
In addition, the scope of equipment supply includes a system of monitoring the residual sorption capacity of adsorption loading.
A combination of adsorbents in the filters allows the required degree of air cleaning by hydrogen sulfide and odor to be reached:
- granulated special hydrophobic impregnated coal with enhanced sorption capacity by hydrogen sulfide (up to 70 % of its own weight);
- alumogel impregnated with potassium permanganate to reduce residual concentration of hydrogen sulfide and other volatile organic compounds.
A prefilter equipped with a pressure differential gage is installed before an adsorption filter for preliminary air cleaning.
A filtering element of the prefilter, a drop and grease catcher, is made of three layers. The first layer is a stainless steel crimped wire net; the second layer includes a stainless steel net twined with spun glass; the third layer is stainless steel crimped wire. The prefilter housing is made of high density polyethylene (HDPE).
Air on the main filter is cleaned due to absorption of contaminating substances.
This type of filter is a closed capacity for two absorption layers. The first sorption layer: УКМ-XL ensures basic reduction in the concentration of hydrogen sulfide and other contaminating substances; the second sorption layer: УКМ-CPS adsorbs residues of hydrogen sulfide until odor is removed.
The basic structural elements of the filter contacting the aggressive medium are made of high density polyethylene (HDPE) resistant to an aggressive medium.
Stage one. Cleaning of air taken from the tunnel manifold shaft in the volume of 1,500 m3/hour, performed in the adsorption filter ВБС-20.
Stage two. Cleaning of air taken from under the coverings of the receiving tank in the volume of 7,000 m3/hour, performed in 2 adsorption filters ВБС-45.
Stage three. Cleaning of air taken from the wet room over the coverings of the receiving tank in the amount of 37,500 m3/hour is performed in 3 adsorption filters АФКТ 12-706-3.