Sorption studies of diethylketone in the presence of Al3+, Cd2+, Ni2+ and Mn2+, from lab-scale to pilot scale

Sustainable permeable biobarriers for atrazine removal in packed bed biofilm reactors

The synergy between two supported bacterial biofilms of S. equisimilis and P. putida and a sustainable biocarrier (raw pine) was studied, working both as biobarriers for the treatment of water contaminated with atrazine. Firstly, the effects of ATZ exposure on bacterial growth were evaluated, with Gram-positive S. equisimilis being a more tolerant bacterium to higher amounts of the herbicide. The bioremoval of ATZ by S. equisimilis concentrated biomass was then assessed, reaching around 83.5% after 15 days due to the potential degradation by the biomass and biosorption by the solids, with overlapping of both mechanisms. The optimization of bacterial biofilm attachment onto raw pine prior to bioremoval assays in lab-scale packed bed biofilm reactors was performed by varying initial biomass concentration, inocula growth time and hydrodynamic conditions. Lastly, the optimized biosystems were tested as sustainable remediation designs to treat water contaminated with the selected herbicide. Results reveal an added beneficial effect towards the bioremoval of atrazine using supported biofilms onto raw pine, reaching 90.42% and 79.71% by S. equisimilis and P. putida biofilms, respectively, over 58.31% increase when compared to sorption on fixed bed of pine. The coupling of biosorption/biodegradation favors the bioremoval process significantly.

Performance of a Combined Bacteria/Zeolite Permeable Barrier on the Rehabilitation of Wastewater Containing Atrazine and Heavy Metals

Several chemicals, such as pesticides and heavy metals, are frequently encountered together in environment matrices, becoming a priority concerning the prevention of their emissions, as well as their removal from the environment. In this sense, this work aimed to evaluate the effectiveness of a permeable biosorbent bio-barrier reactor (PBR) on the removal of atrazine and heavy metals (copper and zinc) from aqueous solutions. The permeable bio-barrier was built with a bacterial biofilm of R. viscosum supported on 13X zeolite. One of the aims of this work is the investigation of the toxic effects of atrazine, copper and zinc on the bacterial growth, as well as the assessment of their ability to adapt to repeated exposure to contaminants and to degrade atrazine. The growth of R. viscosum was not affected by concentrations of atrazine bellow 7 mg/L. However, copper and zinc in binary solutions were able to inhibit the growth of bacteria for all the concentrations tested (5 to 40 mg/L). The pre-acclimation of the bacteria to the contaminants allowed for an increase of 50% of the bacterial growth. Biodegradation tests showed that 35% of atrazine was removed/degraded, revealing that this herbicide is a recalcitrant compound that is hard to degrade by pure cultures. The development of a PBR with R. viscosum supported on zeolite was successfully performed and the removal rates were 85% for copper, 95% for zinc and 25% for atrazine, showing the potential of the sustainable and low-cost technology herein proposed.

A Review on Biological Processes for Pharmaceuticals Wastes Abatement-A Growing Threat to Modern Society

Over the last decades, the production and consumption of pharmaceuticals and health care products grew manifold, allowing an increase in life expectancy and a better life quality for humans and animals, in general. However, the growth in pharmaceuticals production and consumption comes with an increase in waste production, which creates a number of challenges as well as opportunities for the waste management industries. The conventional current technologies used to treat effluents have shown to be inefficient to remove or just to reduce the concentrations of these types of pollutants to the legal limits. The present review provides a thorough state-of-the-art overview on the use of biological processes in the rehabilitation of ecosystems contaminated with the pharmaceutical compounds most commonly detected in the environment and eventually more studied by the scientific community. Among the different biological processes, special attention is given to biosorption and biodegradation.

Pilot-scale sorption studies of diethylketone in the presence of Cd2+ and Ni2. ENVIRONMENTAL TECHNOLOGY 2019;40:942-953. [PMID: 29187066 DOI: 10.1080/09593330.2017.1411979]

The effect of pH on the sorption capacity of vermiculite towards cadmium and nickel was tested in batch systems and it was shown that the sorption percentages increase with an increase in the mass of vermiculite and with an increase in the initial pH. Maximum sorption percentages were obtained for a pH of 8 and 4 g of vermiculite (86.5% for Cd²⁺ and 86.1% for Ni²⁺, for solutions with 100 mg/L of metal). As a consequence, it was possible to establish a range of optimal pH for biosorption processes, by combining the so determined optimal sorption pH of vermiculite with the optimal growth pH of Streptococcus equisimilis, a bacterium used to treat contaminated water. Pilot-scale experiments with a S. equisimilis biofilm supported on vermiculite were conducted in closed-loop conditions, aiming to treat large volumes of diethylketone aqueous solutions, eventually containing Cd²⁺ or Ni²⁺. The excellent capacity of this joint system to simultaneously biodegrade diethylketone and biosorb Cd²⁺ or Ni²⁺was proved. The removal percentage and the uptake increase through time, even with the replacement of the initial solution by new ones. The breakthrough curves that best describe the results achieved for Cd²⁺ and Ni²⁺ are respectively the Adams-Bohart and the Yoon and Nelson model.