A critical review of microbially induced carbonate precipitation for soil stabilization:The global experiences and future prospective

Microbially induced carbonate precipitation(MICP)is a new technology having the potential to induce soil stabilization and provide a green and sustainable comprehensive solution to some geotechnical engineering problems in the environment.The present article is dedicated to present a critical review of this technology and discuss its mechanisms of action and the key factors influencing its performance.The global experiences and national participation from Egypt are demonstrated,in addition to attempts for real life applications.This review provides an insight into the practical steps taken to mitigate some of the current limitations of MICP application and the identified gaps in analogous studies.It was concluded that integrating MICP with existing technologies would favor both engineering needs and market requirements.In addition,providing effective solutions to MICP limitations would highlight this technology as an eco-friendly and cost-effective option to several engineering obstacles.Finally,recommendations focused on encouraging global collaboration for knowledge transfer about this technology among different countries,as well as positive financial support from industrial entities to aid in the progress of scientific research and achieving large-scale applications in the near future,are provided.

Microalgae-based wastewater treatment:Mechanisms,challenges,recent advances,and future prospects

The rapid expansion of both the global economy and the human population has led to a shortage of water resources suitable for direct human consumption.As a result,water remediation will inexorably become the primary focus on a global scale.Microalgae can be grown in various types of wastewaters(WW).They have a high potential to remove contaminants from the effluents of industries and urban areas.This review focuses on recent advances on WW remediation through microalgae cultivation.Attention has already been paid to microalgae-based wastewater treatment(WWT)due to its low energy requirements,the strong ability of microalgae to thrive under diverse environmental conditions,and the potential to transform WW nutrients into high-value compounds.It turned out that microalgae-based WWT is an economical and sustainable solution.Moreover,different types of toxins are removed by microalgae through biosorption,bioaccumulation,and biodegradation processes.Examples are toxins from agricultural runoffs and textile and pharmaceutical industrial effluents.Microalgae have the potential to mitigate carbon dioxide and make use of the micronutrients that are present in the effluents.This review paper highlights the application of microalgae in WW remediation and the remediation of diverse types of pollutants commonly present in WW through different mechanisms,simultaneous resource recovery,and efficient microalgae-based co-culturing systems along with bottlenecks and prospects.

Treating wastewater under zero waste principle using wetland mesocosms

The present investigation demonstrates the synergistic action of using a sedimentation unit together with Cyperus papyrus(L.)wetland enriched with zeolite mineral in one-year round experiment for treating wastewater.The system was designed to support a horizontal surface flow pattern and showed satisfactory removal efficiencies for both physicochemical and bacteriological contaminants within 3 days of residence time.The removal efficiencies ranged between 76.3%and 98.8%for total suspended solids,turbidity,iron,biological oxygen demand,and ammonia.The bacterial indicators(total and fecal coliforms,as well as fecal streptococci)and the potential pathogens(Escherichia coli,Staphylococcus aureus,and Pseudomonas aeruginosa)showed removal efficiencies ranged between 96.9%and 99.8%.We expect the system to offer a smart management for every component according to zero waste principle.The treated effluent was reused to irrigate the landscape of pilot area,and the excess sludge was recycled as fertilizer and soil conditioner.The zeolite mineral did not require regeneration for almost 36 weeks of operation,and enhanced the density of shoots(14.11%)and the height of shoots(15.88%).The harvested plant biomass could be a profitable resource for potent antibacterial and antioxidant bioactive compounds.This could certainly offset part of the operation and maintenance costs and optimize the system implementation feasibility.Although the experiment was designed under local conditions,its results could provide insights to upgrade and optimize the performance of other analogous large-scale constructed wetlands.