Pharmaceuticals are detected at trace levels in waters. Their adverse effects on aquatic ecosystems and human health demand novel pharmaceutical removal technologies for treating wastewater effluents. Iron (Fe) or manganese (Mn) may play important roles in these new technologies since these metals are abundantly available at low costs and are known to contribute to organic conversions via physico-chemical, chemical, and biologically related processes. Few reviews describe and discuss Fe- or Mn-based technologies for the purpose to remove pharmaceuticals from water. Therefore, we review the current literature sorted into the three removal mechanisms, that is., through physico-chemical, chemical, and biological processes. The principals, performance, and influential parameters of these three types of technologies are described. Current and potential applications of these technologies are critically evaluated in order to identify advantages and challenges. In addition, the Fe- or Mn-based technologies which are currently not used but promising to further develop to remove pharmaceuticals cost efficiently are proposed.

Biocontrol formulations prepared from biocontrol bacteria are increasingly applied in sustainable agriculture. Notably, inoculants prepared from Bacillus strains have been proven efficient and environmentally friendly alternatives to chemical bactericides. The bacterium Bacillus velezensis HAB-2 (formerly classified as B. amyloliquefaciens HAB-2) is used as a biological control agent in agricultural fields. In this study, we reported a high-quality genome sequence of HAB-2 using third-generation sequencing technology (PacBio RS II). The 3.89 Mb genome encoded 3,820 predicted genes. Comparative analysis among the genome sequences of reference strains B. velezensis FZB42, B. amyloliquefaciens DSM7 and B. subtilis 168 with the HAB-2 genome revealed obvious differences in the variable part of the genomes, while the core genome shared by FZB42 and HAB-2 was similar (96.14%). However, there were differences in the prophage region among the four strains. The numbers of prophage regions and coding genes in HAB-2 and FZB42 were smaller than the other two strains. The HAB-2 genome showed superior ability to produce secondary metabolites and harbored 13 gene clusters involved in synthesis of antifungal and antibacterial acting secondary metabolites. Furthermore, there were two unique clusters: one cluster which encoded lanthipeptide was involved in mersacidin synthesis and another cluster which encoded ladderane was shown to direct an unknown compound. Multidomain enzymes, such as non-ribosomal peptide synthetase and polyketide synthase, control the biosynthesis of secondary metabolites and rely on 4′-phosphopantetheinyl transferases (PPTases). Key genes lpaH2 and a encoded PPTases in HAB-2 encoded 224 and 120 amino acids, respectively. The genomic features revealed that HAB-2 possesses immense potential to synthesize antimicrobial acting secondary metabolites by regulating and controlling gene clusters. The prophage regions and genes encoding PPTases may provide novel insight for the bacteriostatic mechanism of Bacillus in the biological control of plant diseases.

Applying manganese(IV)- or iron(III)-(hydr)oxides to remove pharmaceuticals from water could be attractive, due to the capacity of these metal oxides to remove pharmaceuticals and be regenerated. As pharmaceutical removal under anaerobic conditions is foreseen, Mn(IV) or Fe(III) regeneration under anaerobic conditions, or with minimum oxygen dosage, is preferred. In this study, batch experiments are performed to investigate (1) Mn(IV) and Fe(III) regeneration from Mn(II) and Fe(II); (2) the pharmaceutical removal during biological Mn(IV) and Fe(III) regeneration; and (3) anaerobic abiotic pharmaceutical removal with different Mn(IV) or Fe(III) species. Results show that biological re-oxidation of reduced Mn(II) to Mn(IV) occurs under oxygen-limiting conditions. Biological re-oxidation of Fe(II) to Fe(III) is obtained with nitrate under anaerobic conditions. Both bio-regenerated Mn(IV)-oxides and Fe(III)-hydroxides are amorphous. The pharmaceutical removal is insignificant by Mn(II)- or Fe(II)-oxidizing bacteria during regeneration. Finally, pharmaceutical removal is investigated with various Mn(IV) and Fe(III) sources. Anaerobic abiotic removal using Mn(IV) produced from drinking water treatment plants results in 23% metoprolol and 44% propranolol removal, similar to chemically synthesized Mn(IV). In contrast, Fe(III) from drinking water treatment plants outperformed chemically or biologically synthesized Fe(III); Fe (III) from drinking water treatment can remove 31-43% of propranolol via anaerobic abiotic process. In addition, one of the Fe(III)-based sorbents tested, FerroSorp®RW, can also remove propranolol (20-25%). Biological regeneration of Mn(IV) and Fe(III) from the reduced species Mn(II) and Fe(II) could be more effective in terms of cost and treatment efficiency.