In line with the development of industrial society, wastewater has caused multiple environmental problems. Contaminants of emerging concern (CECs) in water and wastewater are persistent, and for this reason they can cause serious problems for human health, animal health, and the whole environment. Therefore, it is absolutely necessary to apply efficient methods for the treatment of wastewater that has a high concentration of organic compounds. Over recent years, the prescribed and non-prescribed consumption of antibiotics has increased significantly worldwide. Large quantities of antibiotics are discharged into wastewater because of their incomplete absorption by living organisms. However, even small concentrations present in aquatic environments represent a major risk to human health and environment protection. This paper presents the main advantages and disadvantages of advanced oxidation processes, and the current state and new perspectives in the field of environment protection. This study summarizes data from the most recent specialized scientific literature that focuses on the topic of advanced oxidation processes, thus bringing all these aspects to the attention of researchers in a single work that adds comments and interpretations related to the presented processes. Advanced oxidation processes (AOPs) are often used in the treatment of different types of wastewater. AOPs are based on physicochemical processes that create significant structural changes in chemical species. The majority of antibiotics may be eliminated using physicochemical processes, such as photo-Fenton oxidation, photolysis, ozonation, electrooxidation, heterogeneous catalysis, and other bioprocesses. In comparison to conventional chemical processes, AOPs provide superior oxidation efficiency, ideal operating costs, and zero secondary pollutants.

Drinking and wastewater are to be treated for safe human consumption and for keeping surface waters clean. There are multiple water purification procedures, but the use of ion-exchange resins significantly enhances water purification efficiency. This review was targeted on highlighting the concept and classification of polymeric ion-exchange resins as well as pointing out their real-world applications. Their successful use for purification purposes has been linked to their chemical structure, simplicity of operation, accessibility, and reusability. Therefore, polymeric ion-exchange resins have been used for the removal of a wide range of organic and inorganic pollutants such as pharmaceutical compounds, dyes, organic matter, metals, and many others. Ion-exchange resins are obtained directly by synthesis methods or grafting ionizable groups on polymer matrix in order to ensure continuous improvement. Furthermore, the newly designed ion-exchange resins take into consideration biodegradability potential towards obtaining ecofriendly compounds.

This study presents the behavior of white mustard seedlings Sinapis alba grown for three months in laboratory polluted soil containing As, Cd, Ni and Pb. Four different experiments were performed in which As was combined with the other three toxic metals in different combinations (As, AsCd, AsCdNi, AsCdNiPb), keeping the same concentrations of As and Cd in all tests and following the national soil quality regulations. The effects of these metals were monitored by the analytical control of metal concentrations in soil and plants, bioavailability tests of mobile metal fractions using three different extracting solutions (DTPA + TEA + CaCl₂-DTPA, DTPA + CaCl₂-CAT, and CH₃COONH₄ + EDTA-EDTA) and calculation of bioaccumulation and translocation factors. Additionally, micro, and macro-nutrients both in soil and plant (root, stem, leaves, flowers and seeds) were analyzed in order to evaluate the impact of toxic metals on plant nutrient metabolism. Metals were significantly and differently accumulated in the plant tissues, especially under AsCdNi and AsCdNiPb treatments. Significant differences (p < 0.05) in the concentration of both As and Cd were highlighted. Translocation could be influenced by the presence of other toxic metals, such as Cd, but also of essential metals, through the competition and antagonism processes existing in plant tissues. Significantly, more Cd and Ni levels were detected in leaves and flowers. Cd was also detected in seeds above the WHO limit, but the results are not statistically significant (p > 0.05). The extraction of metallic nutrients (Zn, Cu, Mn, Ni, Mg, K, Fe, Ca, Cr) in the plant was not influenced by the presence of toxic metal combinations, on the contrary, their translocation was more efficient in the aerial parts of the plants. No phytotoxic effects were recorded during the exposure period. The most efficient methods of metal extraction from soil were for As-CAT; Cd-all methods; Pb and Ni-DTPA. The Pearson correlations (r) between applied extraction methods and metal detection in plants showed positive correlations for all toxic metals as follows: As-CAT > DTPA > EDTA, Cd-DTPA > CAT > EDTA, Ni-EDTA = DTPA > CAT, Pb-EDTA = DTPA = CAT). The results revealed that Sinapis alba has a good ability to accumulate the most bioavailable metals Cd and Ni, to stabilize As at the root level and to block Pb in soil.

Simultaneously with the development of industrial society, wastewater with organic pollutants has caused various environmental problems. The most majority of organic pollutants in water and wastewater are persistent, reason which can cause serious problems for human health, animal health, and for the whole environment. Therefore, efficient treatment methods for wastewater with highly concentration of organic compounds are immediately necessary. During the last years, the prescribed and non-prescribed consumption of antibiotics has grown a lot worldwide. Big quantities of antibiotics are discharged into wastewater because their incomplete absorption by living organisms, but at small concentrations present in aquatic environments represents a major risk for the human health and environment protection. The paper presents the main advantages and disadvantages of advanced oxidation processes, but also current state and new perspectives in the field of environment protection. Advanced oxidation processes (AOPs) are often used in the field of treatment of different types of wastewater. AOPs are based on physicochemical processes that create significant structural changes in chemical species, their commercialization at a wide scale may result in cost reductions that are desirable for environmental applications. The majority of antibiotics may be eliminated using physicochemical processes, such as photo-Fenton, photolysis, ozonation, electrooxidation, heterogeneous catalysis, and other bio processes. In comparison to conventional chemical processes, AOPs provide superior oxidation efficiency, ideal operating costs, and zero secondary pollutants.

In this study, a novel material was obtained by functionalizing shredded maize stalk (MS) with Alizarine Red S (ArS), a complexing agent that contains −OH and −C=O groups in its structure (MS-ArS). The obtained MS-ArS was employed in adsorption studies for Mn²⁺, Pb²⁺, Cu²⁺, Cr³⁺, Zn²⁺, and Fe³⁺ (Mⁿ⁺) removal from mixed aqueous matrices. Initially, complex formation between (Mⁿ⁺) and ArS in buffer solution at pH 4 and 10 was investigated using the UV-Vis spectrometric method. Continuous, the functionalization process of MS with ArS was tested at several pH values (2, 4, 6, 8, and 10) using a batch technique. It was observed that the best functionalization of MS with ArS was obtained at pH = 2. Subsequently, Mⁿ⁺ adsorption onto the MS-ArS mass was tested separately at pH 4 and 10. The study achieved that Mⁿ⁺ adsorption proved to be pH dependent. The results confirmed that at pH = 10, Mⁿ⁺ adsorption was increased, compared with pH = 4. MS-ArS has affinity for Mⁿ⁺ in the following order Fe³⁺ > Cu²⁺ > Zn²⁺ > Mn²⁺ > Pb²⁺ > Cr³⁺. Experimental data revealed remarkable desorption rates when 0.5 M HCl was used. After five adsorption/desorption cycles of Mⁿ⁺, the removal capability of MS-ArS was preserved. Overall, the potential of MS-ArS for effective Mⁿ⁺ removal/reuse makes it a sustainable polymer for wastewater treatment applications.

Sewage sludge (SS) resulting from wastewater treatment plants (WWTP) is commonly applied worldwide as a fertilizer in agriculture. This can be done following a rigorous analysis of the sewage sludge composition. Due to its toxic potential, heavy metal ion content is one of the key parameters to test when evaluating SS sample usage as fertilizer. The distribution of metals present in SS samples produced by five municipal WWTPs in Romania was studied. To obtain information regarding metal distribution in SS, a modified ultrasound-assisted extraction procedure of the Community Bureau of Reference (BCR) was employed for As, Cd, Cr, Cu, Mo, Ni, Pb, Zn, and Co quantitation. Concentrations of these metals were measured using ICP-EOS spectrometry. Method extraction accuracy was verified using CRM-483 certified reference material. Results show that extraction efficiency was lowest for the exchangeable fraction for all studied metals. The detected ion metals were found distributed in fractions (F) 2, 3 and 4, which are unavailable for plants and groundwater under natural environmental conditions. One noteworthy finding was that using ultrapure water for the leachate test resulted in low metal solubility, indicating slight metal desorption in real environmental samples. Furthermore, maize stalk bio-adsorbent was used to minimize metal ion content in WWTP leachate samples produced by the storage of SS in terms of metal ion adsorption.