Removal of chelated heavy metals from aqueous solution: A review of current methods and mechanisms

A critical review of one-stage anammox processes for treating industrial wastewater: Optimization strategies based on key functional microorganisms.

Industrial wastewater often contains different complex impurities that are hazardous to the environment and human health, making wastewater treatment a necessity prior to its disposal This review focuses on cell immobilization in the biological wastewater treatment, in which microorganisms are utilized for the biodegradation and removal of different types of contaminants, depending on the type of contaminat Cell immobilization provides the ability to successfully limit the mobility of the cells using synthetic or natural polymers, which can then be used as biocatalysts instead of free cells We provide a comprehensive evaluation of major cells immobilization aspects, starting from the definition of the technology and focusing on a critical and technical analysis of the currently used immobilization techniques including adsorption, covalent binding, entrapment and encapsulation Biological water treatment systems using immobilized cells have the potential to be utilized in the degradation of various types of wastewater contaminants This resulted in remarkable advances in the immobilization techniques, used materials, and properties of immobilized systems Cell immobilization techniques are becoming well developed, new techniques are being studied by researchers, and the trend of advances in this area is expected to continue increasing in the coming years Studies proved that immobilization is an effective and promising technique to enhance biological wastewater treatment processes Immobilized cells could increase the removal efficiency of water contaminants, particularly nutrients, by more than 60% In this review, the main factors in the development of immobilized cells are highlighted, starting from the selection of immobilization support and providing a detailed description of the immobilization techniques The application of cells immobilization for different wastewater treatment processes is illustrated Different examples of wastewater biotreatment are presented, including refractory organics wastewater, wastewater containing heavy metal ions, nitrogen and phosphorous wastewater as well as the removal of dye and color in textile industry wastewater The review ends with a brief overview of future perspectives of research on cells immobilization

Immobilization of microbial cells for the biotreatment of wastewater: A review

Decontamination of heavy metal complexes by advanced oxidation processes: A review

Nitrogen pollution of waters has sometimes caused severe eutrophication, leading to the death of fishes and most aquatic life. There is therefore a need for efficient and cost-effective methods to remove nitrogen from ammonium-rich wastewaters. Anaerobic ammonium oxidation (ANAMMOX) is a promising process to remove nitrogen because this process directly oxidizes ammonium (NH4
 +) to dinitrogen gas (N2) under anoxic condition. Nonetheless, a challenge of this process is that chemolithoautotrophic Anammox bacteria grow slowly at the beginning, thus resulting in low Anammox biomass and instability of reactors. Such issues can be overcome by granulation of the Anammox sludge. Here, we review the characteristics of the Anammox bacteria, and the formation, structure and flotation of Anammox granules under high hydraulic loadings. We also evaluate the performances of full-scale granular Anammox processes. The major points are: 1) Anammox bacteria secrete a large amount of extracellular polymeric substances (EPS), up to 415 mg g−1 of volatile suspended solids (VSS), containing many hydrophobic functional groups that facilitate biomass granulation. 2) Granulation enhances the sludge settling property and retention time, which contributes to the extremely high nitrogen removal rate of 77 kg m−3 d−1 of Anammox upflow reactors. 3) Flotation of Anammox granules frequently occurs under nitrogen removal rate higher than 10 kg m−3 d−1, which is mainly due to the overproduction of EPS under high hydraulic conditions.

Removal of nitrogen from wastewaters by anaerobic ammonium oxidation (ANAMMOX) using granules in upflow reactors

Heavy metals and ammonia are difficult to remove from wastewater, as they easily combine into refractory complexes. The struvite formation method (SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia. The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion. Ammonia was separated from solution as crystalline struvite, and the copper mainly co-precipitated as copper hydroxide together with struvite. Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide. Hydrogen bonding was concluded to be the key factor leading to the co-precipitation. In addition, incorporation of copper ions into the struvite crystal also occurred during the treatment process.

Study on the mechanism of copper–ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal

Physicochemical and microbial properties of settled and floating anammox granules in upflow reactor

The long-term effects of hexavalent chromium on anaerobic ammonium oxidation process: Performance inhibition, hexavalent chromium reduction and unexpected nitrite oxidation.

Cheng Yu

Papers

Removal of nitrogen from wastewaters by anaerobic ammonium oxidation (ANAMMOX) using granules in upflow reactors

Study on the mechanism of copper–ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal

Physicochemical and microbial properties of settled and floating anammox granules in upflow reactor

The long-term effects of hexavalent chromium on anaerobic ammonium oxidation process: Performance inhibition, hexavalent chromium reduction and unexpected nitrite oxidation.

Comparative evaluation of short-term stress of Cd(II), Hg(II), Pb(II), As(III) and Cr(VI) on anammox granules by batch test