STUDY OF EFFECTIVENESS OF SEWAGE TREATMENT IN MEDIUM SAND WITH A SUPPORTIVE SMALL COAL LAYER

Abstract

Aim of the study The aim of the study was to laboratory determine whether introducing a supportive small coal layer with a granulation of 0.02-5 mm will improve the effectiveness of removal of nitrogen and phosphorus compounds from domestic sewage. The study concerned a layer that improves effectiveness of domestic sewage treatment in a household sewage treatment plant under an infiltration drainage system. Material and methods Sewage treatment model study was conducted in a medium sand bed with a supportive small coal layer with a thickness of 0.10 and 0.2 m. Total suspended solids (TSS) were determined with a gravimetric method, BOD5 with an electrochemical method, COD with a titration method with potassium dichromate, ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, total nitrogen and total phosphorus were determined using colorimetric methods, and the reaction with an electrometric method. Results and conclusions It was observed that in terms of basic quality parameters (TSS, BOD5, COD, total nitrogen, total phosphorus) the effectiveness of sewage treatment was compliant with Polish guidelines for sewage disposal into ground and groundwaters. It was determined that a soil bed consisting of medium sand with a supportive layer of small coal with a thickness of 0.20 m is more effective in sewage treatment in comparison to a supportive layer with a thickness of 0.10 m. Application of the supportive layer of small coal with a thickness of 0.2 m in the medium sand soil bed improved the removal effectiveness of TSS by an average 19.8%, of BOD5 by 1.1%, of COD by 4.7%, of total nitrogen by 24.7%, of ammonium nitrogen by 7.1% and of total phosphorus by 30.6% in comparison to the supportive layer with a thickness of 0.10 m. The study confirmed that small coal with granulation of 0.02-5 mm can be used to support removal of nitrogen and phosphorus compounds from sewage with an infiltration drainage system.