Adel Al-Gheethi

The dual roles of phycoremediation of wet market wastewater for nutrients and heavy metals removal and microalgae biomass production

Wastewater generated from fresh, vegetables and meat shops contains high concentrations of nutrients, COD, BOD and TSS. Therefore, the direct discharge of wet market wastewater into natural water may increase the pollution level. Wet market wastewater is rich with nutrients necessary for microalgae growth. Therefore, it represent a superlative environment for producing high quantity of microalgae biomass which have several applications in aquaculture, human nutrition and pharmaceutical industries. Phycoremediation is a process with high potential for the treatment wastewater and removal of nutrients and heavy metals as well as the production of microalgae biomass. However, the main challenges for the phycoremediation technology lie in the wastewater composition, microalgae species, and the competition process between the microalgae strain and the indigenous organisms as well as final utilization of biomass yield. The present review discusses the dual roles of phycoremediation for nutrients and heavy metals removal and microalgae biomass production. The microbiological aspects of phycoremediation, mechanism for heavy metals removal from wastewater, as well as factors affecting wastewater treatment are reviewed. It appears that phycoremediation plays an important role in the treatment of wastewater and production of microalgae biomass.

Removal of heavy metals and antibiotics from treated sewage effluent by bacteria

The increased loads of antibiotics and heavy metals in sewage lead to bacterial cells acquiring resistance to both heavy metals and antibiotics. Therefore, these bacteria can play an important role for removal of pollutants from sewage. The utilization of the microbial processes such as biosorption and enzymatic biodegradation processes has increased during the recent years. These processes are significantly inexpensive and eco-friendly. Enzymatic techniques known as white biotechnology have the ability to degrade complex compounds. Hence, these can be applied to industrial processes. In the current review, the removal of heavy metals and antibiotics from treated sewage effluents by heavy metal/antibiotic-resistant bacteria will be discussed.

Supercritical Carbon Dioxide as Non-Thermal Alternative Technology for Safe Handling of Clinical Wastes

The expansions of communities and cities over the last two decades have led to the increase of the number of health care facilities, and thus, clinical wastes are generated in significant amounts. Clinical wastes are a potential source for many pathogens such as viruses, parasites, fungi and bacteria. Therefore, clinical wastes should be treated before disposal into the environment. The incineration is the most common technology applied for the treatment process. However, the negative effects of incineration on humans and the environment have led scientists to define alternative technologies for the safe disposal of clinical waste. Numerous treatment technologies have been investigated as an alternative for incineration, such as autoclave and microwave. These technologies generally depend on temperature while the recent direction is to use a non-thermal sterilization processes. SC-CO2 is one of the non-thermal sterilization technologies, which depends on pressure and low temperature. Currently, SC-CO2 has been extensively used for the inactivation of microorganisms in food and pharmaceutical industries. However, the application of SC-CO2 in treating clinical wastes has been on a rise. Studies conducted on the inactivation of fungi in food, normal saline and growth media indicate that SC-CO2 has the ability to inactivate these organisms. In clinical wastes, SC-CO2 has been found to be effective in the inactivation of pathogenic bacteria. Therefore, this review paper focuses on the potential of using SC-CO2 as alternative technology for inactivating fungi in clinical wastes.

Reduction of microbial risk associated with greywater by disinfection processes for irrigation

Greywater is one of the most important alternative sources for irrigation in arid and semi-arid countries. However, the health risk associated with the microbial contents of these waters limits their utilization. Many techniques have been developed and used to generate a high microbiological quality of greywater. The main problem in the treatment of greywater lies in the nature of pathogenic bacteria in terms of their ability to survive during/after the treatment process. The present review focused on the health risk associated with the presence of pathogenic bacteria in greywater and the treatment technologies used for the disinfection processes.

Harvesting of microalgae biomass from the phycoremediation process of greywater

The wide application of microalgae in the field of wastewater treatment and bioenergy source has improved research studies in the past years. Microalgae represent a good source of biomass and bio-products which are used in different medical and industrial activities, among them the production of high-valued products and biofuels. The present review focused on greywater treatment through the application of phycoremediation technique with microalgae and presented recent advances in technologies used for harvesting the microalgae biomass. The advantages and disadvantages of each method are discussed. The microbiological aspects of production, harvesting and utilization of microalgae biomass are viewed.

Production and harvesting of microalgae biomass from wastewater: a critical review

The wide range of microalgae applications has increased in the last decade, due to their importance as the source of biofuel and biomass. The potential of wastewater as a culture media lies in the presence of high contents of nutrients and elements required to improve the growth of microalgae and, thus, the high quantity of biomass. However, these properties might be the limitations in the harvesting of microalgae biomass from wastewater. This review discussed the potential of wastewater as the production media for biomass and focused on the harvesting methods, because it represented a major challenge in the quality and quantity of microalgal cells. It can be concluded that among several technologies used for harvesting microalgae biomass from wastewater, the natural flocculant method was the most efficient due to the absence of toxic by-products and secondary effects on the quality of biomass yield, as well as the high biomass quantity.

Potential of bacterial consortium for removal of cephalexin from aqueous solution

Abstract Antibiotics represent a global environmental problem due to their role in the increasing of antimicrobial resistance. Therefore, the removal of antibiotics from wastewater has received unrivalled attention in the recent years. Several technologies including the biodegradation process have been applied for this purpose. However, the potential of bacterial biomass in the biosorption of antibiotics has limited studies. The present study investigated cephalexin removal from aqueous solution by consortium bacterial cells (living and dead) which are tolerant for antibiotics. The factors including cephalexin, biomass, pH, temperature as well as presence of heavy metal ions were tested. The maximum biosorption efficiency was recorded at 0.4 mg L-1 (94.73% vs. 92.98% for living and dead cells respectively), dead cells exhibited more efficiency compared to living cells at 5 mg L-1 (82.36% vs. 46.66% respectively). Living cells are more effective at pH value between pH 4 and 6 (71.95–68.90%). The maximum removal of living cells was highest at 30 °C (80.26%), while was at 25 °C of dead cell biomass (63.81%). Remarkable percentage for cephalexin biosorption by living cells was recorded in the presence low concentrations of Ni2+ (0.21 mg L-1, 40% vs. 30% of living and dead cells, respectively). Living cells exhibited 27.42% and 25% of the removal with Cu2+ (1 mg L-1) and Pb2+ (0.4 mg L-1) respectively. In conclusion the bacterial cells biomass has a potential to remove cephalexin with some negative effects of heavy metals which can be overcome by the removal of these metal ions first and then removal of antibiotics in a second cycle.

Treatment of Wastewater From Car Washes Using Natural Coagulation and Filtration System

Wastewater generated from carwash is one of the main wastewater resources, which contribute effectively in the increasing of environmental contamination due to the chemical characteristics of the car wastes. The present work aimed to develop an integrated treatment system for carwash wastewater based on coagulation and flocculation using Moringa oleifera and Ferrous Sulphate (FeSO4.7H2O) as well as natural filtration system. The carwash wastewater samples were collected from carwash station located at Parit Raja, Johor, Malaysia. The treatment system of car wash wastewater was designed in the lab scale in four stages included, aeration, coagulation and flocculation, sedimentation and filtration. The coagulation and flocculation unit was carried out using different dosage (35, 70, 105 and 140 mg L-1) of M. oleifera and FeSO4.7H2O, respectively. The efficiency of the integrated treatment system to treat carwash wastewater and to meet Environmental Quality Act (EQA 1974) was evaluated based on the analysis of pH, dissolved oxygen (DO), chemical oxygen demand (COD) and turbidity (NTU). The integrated treatment system was efficient for treatment of raw carwash wastewater. The treated carwash wastewaters meet EQA 1974 regulation 2009 (Standards A) in the term of pH and DO while, turbidity and COD reduced in the wastewater to meet Standards B. The integrated treatment system designed here with natural coagulant (M. oleifera) and filtration unit were effective for primary treatment of carwash wastewater before the final disposal or to be reused again for carwash process.

Influence of pathogenic bacterial activity on growth of Scenedesmus sp. and removal of nutrients from public market wastewater

The present study aims to investigate the influence of Staphylococcus aureus, Escherichia coli and Enterococcus faecalis in public market wastewater on the removal of nutrients in terms of ammonium (NH4-) and orthophosphate (PO43) using Scenedesmus sp. The removal rates of NH4- and orthophosphate PO43- and batch kinetic coefficient of Scenedesmus sp. were investigated. The phycoremediation process was carried out at ambient temperature for 6 days. The results revealed that the pathogenic bacteria exhibited survival potential in the presence of microalgae but they were reduced by 3-4 log at the end of the treatment process. The specific removal rates of NH4- and PO43- have a strong relationship with initial concentration in the public market wastewater (R2 = 0.86 and 0.80, respectively). The kinetic coefficient of NH4- removal by Scenedesmus sp. was determined as k = 4.28 mg NH4- 1 log10 cell mL-1 d-1 and km = 52.01 mg L-1 (R2 = 0.94) while the coefficient of PO43- removal was noted as k = 1.09 mg NH4- 1 log10 cell mL-1 d-1 and km = 85.56 mg L-1 (R2 = 0.92). It can be concluded that Scenedesmus sp. has high competition from indigenous bacteria in the public market wastewater to remove nutrients, with a higher coefficient of removal of NH4- than PO43.

An overview of the utilisation of microalgae biomass derived from nutrient recycling of wet market wastewater and slaughterhouse wastewater

Microalgae have high nutritional values for aquatic organisms compared to fish meal, because microalgae cells are rich in proteins, lipids, and carbohydrates. However, the high cost for the commercial production of microalgae biomass using fresh water or artificial media limits its use as fish feed. Few studies have investigated the potential of wet market wastewater and slaughterhouse wastewater for the production of microalgae biomass. Hence, this study aims to highlight the potential of these types of wastewater as an alternative superior medium for microalgae biomass as they contain high levels of nutrients required for microalgae growth. This paper focuses on the benefits of microalgae biomass produced during the phycoremediation of wet market wastewater and slaughterhouse wastewater as fish feed. The extraction techniques for lipids and proteins as well as the studies conducted on the use of microalgae biomass as fish feed were reviewed. The results showed that microalgae biomass can be used as fish feed due to feed utilisation efficiency, physiological activity, increased resistance for several diseases, improved stress response, and improved protein retention.