Abstract
Due to various ecological problems, it is required to remove the ammonia nitrogen from wastewater. Industrial wastewater that was not subjected to any purification was used in this study, while most processes described in the literature were carried out using synthetically prepared solutions. The study investigated the removal of ammonium ions using ion exchange on various commercial minerals, in 3 h long batch ion-exchange experiments. Furthermore, research on the sodium chloride activation of the selected mineral was conducted. The screening of the mineral with the highest removal potential was conducted taking into account the adsorption capacity (q) and maximal removal efficiency (E), based on the NH4+ ions changes determined using the selective electrode and spectrophotometric cuvette tests. The highest adsorption capacity (q = 4.92 mg/g) of ammonium ions with the maximum removal efficiency (52.3%) was obtained for bentonite, with a 0–0.05 mm particle size. After pretreatment with a 1 mol/L NaCl solution, maximum efficiency increments were observed (55.7%). The Langmuir adsorption isotherm corresponds well with the equilibrium adsorption data (R2 from 0.97 to 0.98), while the Freundlich model was found to be mismatched (R2 = 0.77). Based on these results it was concluded that natural sorbents may be effectively applied in wastewater treatment. It can be observed that as the size of sorbent particles gets lower, the adsorption capacity, as well as the removal efficiency, gets higher. The bentonite pretreatment with the NaCl solution did not result in the expected efficiency improvement. The 2 mol/L solution affected about 3.5% of the removal efficiency yield.
Highlights
Municipal, industrial, and agricultural activities generate ammonia nitrogen discharges into environmental resources
The minerals used in the present study belong to the silicate family with commercial names: Zeocem Eco provided by Zeocem a.s., Bystré, Slovakia with particle sizes of 0–0.05 mm and 0.5–1 mm, Biozeo R01 from BioDrain Ltd., Rzeszów, Poland with a 0.5–1.0 mm fraction, Zeolite Subio provided by Subio Eko Polska Ltd., Krzyżanowice, Poland with a granulation of 0–0.2 mm, 0.2–0.5 mm, and
It was found that the lower the mineral size, the higher the adsorption capacity as well as removal efficiency
Summary
Industrial, and agricultural activities generate ammonia nitrogen discharges into environmental resources. The excessive accumulation of ammonium that is discharged into water can cause serious ecological problems, such as: The accelerated eutrophication of lakes and rivers, the depletion of dissolved oxygen, and toxicity in fish and other aquatic animals in the water body [1]. The removal of ammonia from processes or waste effluents is required, due to its toxicity. The most widely used methods for removing ammonia from wastewater are air stripping [6,7], ion exchange [8,9], breakpoint chlorination [10], and biological nitrification-denitrification [11,12]. The traditional method of removing ammonia from municipal and industrial wastewaters is based on biological treatments. It can be inhibited by toxic shock, pH change, low-dissolved oxygen, and low temperature in winter [11,12]
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