# The Use of Chalcogenite as a Biosorption Bed in the Treatment of Groundwater
## 1 Introduction
The sorption qualities of the materials was filled by the biofilter and the capability to stop the microorganisms carried by water cause the biomass embedded on the carrier, along with the gradual depletion of sorption capacity of the biofilter to take over its function, sorbing the substances present in water, processing them for building material, and products of biochemical changes providing the energy for cells. Groundwater purification technology is not as complicated as surface water treatment technology. However, this process is more difficult when, in addition to iron (which can usually be easily removed in a traditional aeration and filtration system), there are also other admixtures, such as manganese (II), ammonium nitrogen, or organic compounds [14; 22; 23; 24; 25]. The physicochemical methods used to remove iron, manganese, and ammonium nitrogen from water include adsorption, ion exchange, membrane processes, filtration, and chemical oxidation [9; 26]. The pollution of groundwater with nitrogen compounds, especially ammonium nitrogen, which has been observed in recent years, requires a constant search for unconventional and highly effective purification processes. The methods used so far either do not always give satisfactory results or they require a significant financial investment. The biofiltration process executed in devices involving biofilm formation on a solid substrate is the most popular method for purifying groundwater from excessive amounts of ammonium nitrogen [27]. Filtration through biosorbent beds is considered to be a highly effective process but at the same time, its effectiveness depends on many factors. In addition to appropriate selection of the carrier, they include the appropriate selection of process parameters and treatment technology adapted to the properties and composition of the treated water. The methodology of testing the technological suitability of filtration materials for the execution of a specific groundwater treatment task requires a series of studies to measure its potential effectiveness [28; 29]. Using a continuous sorption system allows a better approach to real industrial applications. A few models that can describe these processes have been reported in the literature [22; 30]. However,only a limited number of references exist on the modelling of the combined and simultaneous removal of the above pollutants [6; 9]. [PERSON] et al. attempted to estimate the optimal dimensions of a biofilter for the simultaneous removal of iron, manganese, and ammonia in a groundwater treatment plant [15]. Consequently, in packed bed bioreactors, such as trickling filters, bio-sand filters, etc., a more general equation is frequently used. [PERSON] and [PERSON] also attempted to model the process of simultaneous iron and manganese removal. They state that removal kinetics of contaminants during water treatment is an important issue, as it could provide information about the time required for efficient removal of a specific contaminant, which is necessary when designing treatment units. Furthermore, reaction rates can be estimated from the results of kinetic analysis and compared to those for abiotic removal. They found that biologically mediated manganese and iron removal followed a first-order reaction rate, presenting half-lives of 3.98 and 0.9 min, respectively. Their kinetic results also indicated that rates of manganese and iron oxidation were several orders of magnitude higher than those for abiotic oxidation [31]. Among the materials that can be used as biosorbent beds, chalcedonites deserve particular attention. Their chemical composition and physical properties create opportunities for multi-purpose use. Characteristics of chalcedonites are influenced by the forms of SiO\({}_{2}\) minerals that build them, as well as certain amounts of calcium, magnesium, aluminum, iron, and manganese oxides.