Treatment of landfill leachates from Fez city (Morocco) using a sequence of aerobic and Fenton processes

Leachate decontamination through biological processes coupled to advanced oxidation: A review

The landfill leachate is considered a toxic effluent composed of recalcitrant contaminants that requires innovative alternatives for its decontamination. Coupling between advanced oxidation processes (AOPs) and aerobic biological treatments are highlighted in this research. Therefore, a bibliographic review of the research made from 2010 to 2021 was developed. These combined alternatives were applied in leachates, and it is oriented toward the analysis of knowledge gaps, trends, and future proposals of the treatment combined that contribute to researchers who wish to work on the subject. These kinds of treatments were chosen due to a bibliometric analysis made. Also, the information was searched in several scientific database. This work was found to be unpublished, as no reviews were found so far that agglomerate studies of coupling between photocatalytic and aerobic biological processes to treat leachates. Besides, AOPs are ideal for treating wastewater of complex composition, however, when it is used as the only treatment, they are usually unprofitable, which justifies their coupling with biological treatments. Subsequently, it was determined that the knowledge main gap is the lack of documentation of treatment costs, which makes it difficult to implement on a real scale. In addition to this, the couplings trends are toward doping with metallic and nonmetallic ions of the catalyst used in the photocatalytic process to improve the efficiency of these. Finally, future research should work on finding alternatives that allow the optimization of the resources used in the combined systems and on promoting the recovery of existing products in the leachate.Implications: Leachates generate several environmental impacts due to their toxic composition. Even when coupling between heterogeneous photocatalysis and biologic treatment can solve them, issues like cost analysis and the scaling-up factor have not been developed, and futures researchers should work on that. Besides, the trend founded in almost all investigations was the catalyst doping with metals and nonmetals ions, particularly when they use TiO2 because it gives the possibility of improving efficiencies just with a structural variation. Finally, these treatment combinations require more analyses and comparison of their remotion over emerging pollutants and their performance with new designs.

Biotechnological potential of microorganisms from landfill leachate: isolation, antibiotic resistance and leachate discoloration

Disposal of municipal solid waste (MSW) can be considered a risk to human health representing a great environmental problem in several countries. MSW landfills are a significant source of toxic elements in the environment. Microorganisms able to thriving in leachate wastewater may exhibit metabolic machinery to synthesize a wide range of enzymes able to degrade and/or discolor toxic compounds from leachate. The use of non-pathogenic microbial cells for human health, recovered from leachate for biotechnological application, can be considered a promising approach in bioremediation processes of toxic compounds found in these environments. The present work aimed to the isolation, antibiotic resistance evaluation and leachate discoloration by microorganisms isolated from landfill leachate of Foz do Iguaçu. Forty bacteria and fifteen filamentous fungi were isolated. From these, six bacterial showed resistance at least one tested antibiotic, while six fungal isolates showed resistance to the antimycotic nystatin. CCMIBA_4L (unidentified bacteria) and Paecilomyces sp. CCMIBA_5N, were able to discolor 19.15% and 25.26% of the leachate, respectively. The results of the present work encourage future studies to characterize the enzymes involved in the discoloration and degradation of the leachate. The findings demonstrated the potential for the use of microorganisms from landfill leachate as bioremediation tools.

Emerging Pollutants in Moroccan Wastewater: Occurrence, Impact, and Removal Technologies

The rapid growth of anthropogenic activities in recent decades has resulted in the appearance of numerous new chemical compounds in the environment, known as “emerging pollutants” (EPs) or “contaminants of emerging concern” (CECs). Although partially or not yet regulated or monitored, there is growing research interest in these EPs among the scientific community because of their bioaccumulation, persistence, and adverse effects. Among these, endocrine disruptors, pesticides, and pharmaceuticals can have harmful impacts on human health and the ecosystem. Conventional wastewater treatment technologies are not effective in removing these contaminants, allowing them to be released into the receiving environment. In order to improve the understanding of emerging pollutants, this review discusses the source, occurrence, and impacts of bisphenol A, atrazine, amoxicillin, and paracetamol as model molecules of emerging environmental pollutants, an issue that remains underrepresented in Morocco. Then, treatment methods for EPs are reviewed, including adsorption, advanced oxidation processes, biodegradation, and hybrid treatment. It is proposed that adsorption and photocatalysis can be used as simple, effective, and environmentally friendly technologies for their removal. Thus, we summarize some of the adsorbent and photocatalyst materials applied in recent work to control these pollutants. Towards the end of this paper, the development of inexpensive and locally available (Morocco) materials to remove these compounds from wastewater is considered.