Wastewater is the main source of environmental pollution and it contains numerous pollutants, and many of them, including phenolic compounds and heavy metal ions, are very toxic and potentially hazardous to public health. The first part of the thesis focuses on phenol remediation. We study new hierarchical hybrid biocatalysts comprised of horseradish peroxidase (HRP), magnetic nanoparticles and microparticles for advanced oxidation processes. The hybrid peroxidase catalysts exhibit activity three times higher than free HRP and are able to remove three times more phenol compared to free HRP under similar conditions. In addition, the hybrid catalysts reduce substrate inhibition, which is common with free or conventionally immobilized enzymes. We improve the reusability of the system when the HRP/magnetic nanoparticle hybrids are supported on micron scale magnetic particles. The second part of the thesis focuses on a mesoporous bis-amine bridged polysilsesquioxane sorbent for heavy metal ion removal. We synthesize a mesoporous sorbent by hydrolysis and condensation of amine-bridged precursor in the presence of a nonionic surfactant. The sorbent exhibits a high adsorption capacity of 77 mg/g (1.2 mmol/g) and 276 mg/g (1.3 mmol/g) for Cu (II) and Pb(II), respectively. After metal adsorption we can easily regenerate the system to full capacity. The sorbent shows high selectivity for Cu (II) over Ni (II) and Co (II) but it becomes deactivated in the presence of a small amount of adsorbed Cr (III) ions. We also apply this sorbent to adsorb CO2. It exhibits fast CO2 capture kinetics and has a CO2 capacity of 2.4 mmol/g. We can fully regenerate the sorbent and it shows good stability over repetitive adsorption-desorption process over 10 cycles.