The science of the total environment

Water pollution is one of the global challenges that society must address in the 21st century aiming to improve water quality and reduce human and ecosystem health impacts. Industrialization, climate change, and expansion of urban areas produce a variety of water pollutants. In this work, we discuss some of the most recent and relevant findings related to the release of heavy metals, the possible risks for the environment and human health, the materials and technologies available for their removal. Anthropogenic activities are identified as the main source of the increasing amounts of heavy metals found in aquatic environments. Some of the health hazards derived from repeated exposure to traces of heavy metals, including lead, cadmium, mercury, and arsenic, are outlined. We also give some perspectives about several techniques used to detect heavy metals, as well as about the factors that could affect the contaminant removal. The advantages and drawbacks of conventional and non-conventional heavy metal removal methods are critically discussed, given particular attention to those related to adsorption, nanostructured materials and plant-mediated remediation. Some of the commercial products currently used to eliminate heavy metals from water are also listed. Finally, we point out some the requirements and opportunities linked to developing efficient methods for heavy metal removal, such as the ones that exploit nanotechnologies.

Heavy metal water pollution: A fresh look about hazards, novel and conventional remediation methods

Today, heavy metal pollution is of prime concern from the environmental point of view. Among the heavy metals, manganese is a very common contaminant of wastewater and ground water, as it is a significant raw material for industry. This paper reviews various technologies that have been used to treat manganese containing wastewater and ground water, such as chemical precipitation, coagulation, flotation, ion-exchange, oxidation/filtration, electrochemical treatment, adsorption, and membrane filtration. Recovery of manganese is also very imperative due to its economical and environmental aspects.

A review of technologies for manganese removal from wastewaters

The role of biogenic Fe-Mn oxides formed in situ for arsenic oxidation and adsorption in aquatic ecosystems

Bioaerosol concentration was measured in wastewater treatment units in south of Tehran, the largest wastewater treatment plant in the Middle East. Active sampling was carried out around four operational units and a point as background. The results showed that the aeration tank with an average of 1016 CFU/m3 in winter and 1973 CFU/m3 in summer had the greatest effect on emission of bacterial bioaerosols. In addition, primary treatment had the highest impact on fungal emission. Among the bacteria, Micrococcus spp. showed the widest emission in the winter, and Bacillus spp. was dominant in summer. Furthermore, fungi such as Penicillium spp. and Cladosporium spp. were the dominant types in the seasons. Overall, significant relationship was observed between meteorological parameters and the concentration of bacterial and fungal aerosols.

Assessment of bioaerosol contamination (bacteria and fungi) in the largest urban wastewater treatment plant in the Middle East

Heavy metal contamination is one of the most important environmental issues. Therefore, appropriate steps need to be taken to reduce heavy metals and metalloids in water to acceptable levels. Several treatment methods have been developed recently to adsorb these pollutants. This paper reviews the ability of residuals generated as a by-product from the water treatment plants to adsorb heavy metals and metalloids from water. Water treatment residuals have great sorption capacities due to their large specific surface area and chemical composition. Sorption capacity is also affected by sorption conditions. A survey of the literature shows that water treatment residuals may be a suitable material for developing an efficient adsorbent for the removal of heavy metals and metalloids from water.

https://www.mdpi.com/2075-163X/9/8/487/pdf

Removal of Heavy Metals and Metalloids from Water Using Drinking Water Treatment Residuals as Adsorbents: A Review

This article presents microbiological air pollution around wastewater treatment plants in Slupca, Kostrzyn, and Września, and the Complex Wastewater Treatment and Wastes Composting Plant in Grodzisk Mazowiecki, Poland. The samples of air were collected using the sedimentation and aspiration methods. The largest group of microorganisms in the monitored air were psychrophilic and mesophilic bacteria and microscopic fungi. The number of psychrophilic bacteria ranged from 78 to 225,000 CFU/m 3 , the number of mesophilic bacteria varied in the range from 0 to 195,000 CFU/m 3 and the fungi – from 0 to 65,700 CFU/m 3 of air. The amount of other bacteria (Staphylococcus, Pseudomonas fluorescens, and coliforms) ranged from 0 to 87,500 CFU/m 3 . A great number of bacteria and fungi has been detected near sewage aeration tanks, places of sludge disposal, and grit chambers. The interpretation of the results has been conducted according to the Polish Standards, which classify the degree of air pollution in reference to the number of microflora in the air. A change in air pollution has been noted depending on the season and climatic conditions (wind strength in particular). Research has shown that coliform bacteria, although not included in the Polish Standard, constitutes a good indicator of microorganisms’ emission from sewage into the air.

Microbiological air monitoring around municipal wastewater treatment plants

Best practice guide on the control of iron and manganese in water supply / ed. by Adam Postawa, Colin Hayes

The standard groundwater treatment technology is a simple, non-chemical reagent technology based on aeration and filtration processes. This treatment technology is resulted in the formation of groundwater treatment sludge (GWTS). Because one of the elements of sustainable development is the possibility of their reuse, that water treatment plant operators are looking for new ways of managing these sludges. At present, not all factors determining the adsorptive capacity of water treatment sludge are known. The explanation why the adsorption capacity of sludge with a similar structure and chemical composition may differ significantly will allow for their wider use as adsorbents. The information which must be known to ensure proper sludge management are the quality, chemical composition and texture characteristics of the GWTS. The sludges were characterized by X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy and N2 adsorption/desorption isotherms. The results showed that the composition and properties of the GWTS depend primarily on the quality parameters of the raw water and the processes and reagents used in its treatment technology. GWTS contains mainly amorphous iron oxides. Sludges are characterized by a large specific surface area (145 m2/g). Due to composition and textural parameters, GWTS demonstrates good adsorption properties toward different compounds such as heavy metals and metalloids. In this article, the authors describe the relationship between properties of resulting sludge and the properties of groundwater, the treatment technology and backwash water treatment from rapid filters.

/pdf/the-properties-of-sludge-formed-as-a-result-of-coagulation-wtocxpp197.pdf

Alina Pruss

Papers

Removal of Heavy Metals and Metalloids from Water Using Drinking Water Treatment Residuals as Adsorbents: A Review

Microbiological air monitoring around municipal wastewater treatment plants

Best practice guide on the control of iron and manganese in water supply / ed. by Adam Postawa, Colin Hayes

The properties of sludge formed as a result of coagulation of backwash water from filters removing iron and manganese from groundwater

Selection of the surface water treatment technology - a full-scale technological investigation.