Lck302

Total ammonium nitrogen (TAN) was determined using colorimetric verification via cuvette tests LCK302 (Hach Lange GmbH, Germany). Free ammonia nitrogen (FAN) was calculated from TAN value in respect to temperature and pH according to the formula given by Astals and colleagues [74 (link)]. Total organic- and inorganic-carbon (TOC and TIC, respectively) were measured via LCK381, total nitrogen was determined via LCK 338, (Hach Lange GmbH, Germany). The determination of volatile fatty acid (VFA) concentrations was performed via GC-FID analysis. Sample preparation was done according to the 5560D procedure [75 ] and analyzed using a Shimadzu GC-2010 plus Gas Chromatograph equipped with a Macherey–Nagel OPTIMA^® FFAPplus (Length: 30 m, inner diameter: 0.25 mm) column (Macherey–Nagel, Germany) and coupled to an FID detector (supplied with H₂ and synthetic air). Analysis was performed under constant pressure of 231.9 kPa with He as carrier gas and N₂ as makeup gas with constant flow rate of 60 cm s⁻¹. Column temperature in the first 2 min was at 100 °C with following linear increase to 175 °C within 15 min. VFA-Mix standard (46975-U, Supelco Analytical, Sigma-Aldrich, USA) at concentrations of 0.1, 1 and 10 mM was used for calibration.

The NH₄⁺ adsorption capacity (q) and removal efficiency (E) of mineral were calculated using the equations:
and

respectively, where: q (adsorption capacity at time t) is the total amount of adsorbed NH₄⁺ ions per unit of weight of mineral at time t (mgN/g_z); C₀,C_t, C_e are the initial, time t, and equilibrium concentrations of NH₄⁺ in solution (mg N/L); V is the initial volume of treated effluent (L); m is the adsorbent mass (g).
The content of ammonium ions in the wastewater was determined using the ammonium ion-selective electrode (DETEKTOR, Raszyn, Poland) with the silver-chloride reference electrode (DETEKTOR, Raszyn, Poland) and the ionometer (ELMETRON CPI-505, Zabrze, Poland). To control the values obtained by means of using the ammonium ion-selective electrode, the spectrophotometric Hach-Lange cuvette tests (LCK 302) (HACH LANGE Ltd., Wrocław, Poland) [30 ] have been used, and the initial and final concentration has been measured in the course of the experiments.
The chemical oxygen demand (COD) was determined spectrophotometrically using the HACH-Lange cuvette tests (LCK 514) (HACH LANGE Ltd., Wrocław, Poland) [30 ] at the beginning and end of each experiment, when the sorbent activation with NaCl has been studied to verify the possibility of COD removal.