Microorganisms In Wastewater Treatment Research Articles

Response of anammox consortia to inhibition from high ferroferric oxide nanoparticles concentration and potential recovery mechanism

The substantial discharge of ferroferric oxide nanoparticles (Fe3O4 NPs) into sewage threatens the survival of functional microorganisms in wastewater treatment. This study elucidated responses of anaerobic ammonium oxidation (anammox) consortia to inhibition from high Fe3O4 NPs concentration and recovery mechanisms. The nitrogen removal efficiency decreased by 20.3 % and recovered after 55 days under 1000 mg/L Fe3O4 NPs concentration. Toxicity was attributed to reactive oxygen species (ROS) production. The excessive ROS damaged membrane integrity, nitrogen metabolism, and DNA synthesis, resulting in the inhibition of anammox bacteria activity. However, recovery mechanisms of anammox consortia activity were activated in response to 1000 mg/L Fe3O4 NPs. The increase of heme oxygenase-1, thioredoxin, and nicotinamide adenine dinucleotide-quinone oxidoreductase genes alleviated oxidative stress. Furthermore, the activation of metabolic processes associated with membrane and DNA repair promoted recovery of anammox bacteria activity. This study provided new insights into NPs contamination and control strategies during anammox process.

Impacts of exogenous C6-HSL on the enhanced cometabolic removal of sulfadiazine by enriched nitrifying sludge

The antibiotics in the wastewater could be effectively removed by the cometabolism of nitrifying sludge mediated by ammonia monooxygenase (AMO). The effects of quorum sensing (QS) system regulated by N-acyl homoserine lactones (AHLs) on the performance and functional microorganisms in wastewater treatment have also been increasingly reported, yet few studies report the impacts of AHLs on the cometabolic removal of antibiotics by nitrifying bacteria. In this study, N-hexanoyl-L-homoserine lactone (C6-HSL) and sulfadiazine (SDZ) were selected, and a series of batch tests were implemented to study the cometabolic degradation of SDZ by enriched nitrifying sludge and the responses of the sludge under different concentrations of exogenous C6-HSL (0.1, 0.5 and 1 μM). The results indicated C6-HSL enhanced the cometabolic removal of SDZ by nitrifying sludge, with the highest removal efficiency of 84.60 % achieved with 1 μM C6-HSL. The extracellular polymeric substances (EPS) increased by 50.8 %–139.5 %，and a positive correlation between the increase of protein content in EPS and the concentration of C6-HSL was established. C6-HSL also brought an increase in cellular adenosine triphosphate content, which increased by 51.8 % with 1 μM C6-HSL. Moreover, C6-HSL up-regulated the amoA gene and enhanced AMO activity, which led to the sufficient degradation of SDZ.

Combination of peracetic acid dosing with diffused aeration in municipal wastewater treatment.

Wastewater aeration is an important unit operation that provides dissolved oxygen for microorganisms in wastewater treatment. In this study, the impact of peracetic acid (PAA) dosing on wastewater aeration was assessed in terms of oxygen transfer, visual observation of bubble size changes, and evolution of dissolved oxygen from PAA (and H2O2) decomposition. Oxygen transfer coefficients improved with PAA concentrations of up to 7 mg/L, which was probably due to the smaller bubbles being formed from the aeration diffuser and evolution of small bubbles from PAA (and H2O2) decomposition. At a PAA concentration higher than 7 mg/L, the accumulation of acetate molecules to the gas-liquid interface of bubbles likely began to counteract the positive impact of bubble size decrease by increasing the mass transfer resistance of oxygen from bubbles to water. Finally, a continuous bench-scale primary effluent aeration experiment demonstrated that at a continuous PAA dosing of 1 mg/L, the air input by a compressor could be decreased by 54%, while keeping the oxygen level constant at approximately 1.5 mg/L. PAA dosing could be combined, for example, with aerated grit removal to enhance the primary effluent aeration together with additional benefits of partial disinfection and odor formation prevention.

Emerging Applications of Chlorella sp. and Spirulina (Arthrospira) sp.

Chlorella sp. and Spirulina (Arthrospira) sp. account for over 90% of the global microalgal biomass production and represent one of the most promising aquiculture bioeconomy systems. These microorganisms have been widely recognized for their nutritional and therapeutic properties; therefore, a significant growth of their market is expected, especially in the nutraceutical, food, and beverage segments. However, recent advancements in biotechnology and environmental science have led to the emergence of new applications for these microorganisms. This paper aims to explore these innovative applications, while shedding light on their roles in sustainable development, health, and industry. From this state-of-the art review, it was possible to give an in-depth outlook on the environmental sustainability of Chlorella sp. and Spirulina (Arthrospira) sp. For instance, there have been a variety of studies reported on the use of these two microorganisms for wastewater treatment and biofuel production, contributing to climate change mitigation efforts. Moreover, in the health sector, the richness of these microalgae in photosynthetic pigments and bioactive compounds, along with their oxygen-releasing capacity, are being harnessed in the development of new drugs, wound-healing dressings, photosensitizers for photodynamic therapy, tissue engineering, and anticancer treatments. Furthermore, in the industrial sector, Chlorella sp. and Spirulina (Arthrospira) sp. are being used in the production of biopolymers, fuel cells, and photovoltaic technologies. These innovative applications might bring different outlets for microalgae valorization, enhancing their potential, since the microalgae sector presents issues such as the high production costs. Thus, further research is highly needed to fully explore their benefits and potential applications in various sectors.

Deciphering physicochemical properties and enhanced microbial electron transfer capacity by magnetic biochar

Magnetic biochar is important for improving the electron transfer capacity (ETC) of microorganisms in wastewater treatment. In this study, three magnetic biochar under different pyrolysis temperatures (300, 500 and 700 °C) were prepared by co-precipitation, and their characteristics and impacts on mediating microbial ETC were investigated. Results indicated that magnetic biochar had a higher capacitance and conductivity than pyrolytic biochar, with the largest specific capacitance of 14.7F/g for FCS700 (magnetic biochar prepared at 700 °C). The addition of magnetic biochar could improve the nitrogen removal efficiency of a sludge-biochar system. The electron transfer resistance (Rct) of magnetic biochar was lower than pyrolytic biochar by 25.5 % (300 °C), 19.7 % (500 °C), and 11.6 % (700 °C), respectively. The structure of the microbial community in the sludge-biochar system differed significantly. Spearman correlation suggested that the electrochemical properties of biochar were an important factor affecting the structure of the microbial community.

Antimicrobial photodynamic inactivation of wastewater microorganisms by halogenated indole derivative capped zinc oxide

Novel 5-bromoindole (5B)-capped zinc oxide (ZnO) nanoparticles (5BZN) were synthesized to improve the antibacterial, antibiofilm, and disinfection processes for the control of microorganisms in wastewater treatment. When exposed to 5BZN, the biofilm density and cell attachment were reduced dramatically, as measured by scanning electron microscopy (SEM). The 5BZN were also investigated for photodynamic treatment of multidrug-resistant (MDR) bacteria and toxicity. The combination of 5B and ZnO exhibited strong antibacterial and antibiofilm activities against MDR bacteria even at low doses (20 μg/mL). After 12.5 mW/cm2 blue LED irradiation, the composite 5BZN showed superior photodynamic inactivation of two wastewater MDR, Enterobacter tabaci E2 and Klebsiella quasipneumoniae SC3, with cell densities reduced by 3.9 log CFU/mL and 4.7 log CFU/mL, respectively, after 120 min. The mechanism of bacterial inactivation was studied using a scavenging investigation, and H2O2 was identified mainly as the reactive species for bacterial inactivation. The 5BZN exhibited higher photodynamic inactivation towards the total coliform bacteria in wastewater effluents under a blue LED light intensity of 12.5 mW/cm2 with almost complete inactivation of the coliform bacteria cells within 40 min. Furthermore, when 5BZN (100 mg/L) was added to the reactor, the level of tetracycline antibiotic degradation was increased by 63.6% after 120 min. The toxicity test, animal model nematode studies and seed germination assays, showed that 5BZN is harmless, highlighting its tremendous potential as a self-healing agent in large-scale photodynamic disinfection processes.

Special Issue: The Application of Microorganisms in Wastewater Treatment

Today, water is an integral part of the course of our lives, from the operation and maintenance of households to extensive industrial and agricultural use [...]

The Role of Microorganisms in Distillery Wastewater Treatment: A Review

Distilleries are one of the most polluting industries generating large volume of wastewater having a serious environmental concern. Distillery effluent is characterized by dark brown color, acidic pH, high temperature, low dissolved oxygen (DO), high biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Distillery wastewater disposed onto the environment prior to treatment is hazardous and leads to soil and water pollution. The dark brown color of distillery effluent causes reduction of sunlight penetration, decreased photosynthetic activity and dissolved oxygen concentration in rivers, lakes and lagoons, hence becomes detrimental to aquatic life. It also causes reduction in soil alkalinity and inhibition of seed germination. Different physicochemical and biological methods have been investigated for the treatment of distillery effluents. In recent years, increasing attentions has been directed towards biological wastewater treatment methods. Bioremediation of wastewater using microorganisms is efficient and cost effective method. Microorganisms as bacteria, fungi, and algae have been shown to exhibit bioremediation activities mainly due to their production of complex and non-specific enzymatic systems capable of degrading various forms of pollutants from wastewater. The main concern of the present review is also to explore the role of microorganisms in wastewater treatment disposed from distilleries. Further, the mechanisms of color removal by fungi, bacteria and algae have also been incorporated.

Pollution Indicators and Pathogenic Microorganisms in Wastewater Treatment: Implication on Receiving Water Bodies

There is the indication that human deaths as a result of water-borne diseases exceed five million people per year, with over half of the diseases being microbial intestinal infections, especially cholera and diarrhea. A number of pathogenic microorganisms, regarded as water pollution indicators have been observed as the agents of such. These water pollution indicators are present in feces, sewage and can survive as long as pathogenic organisms. These pathogenic microorganisms cause several waterborne infections and diseases like bacterial (cholera, salmonellosis, shigellosis and several diseases associated with pathogenic strains of E. coli), viral (ranging from a mild febrile illness to myocarditis, meningoencephalitis, poliomyelitis, herpangina, hand-foot-and mouth disease and neonatal multi-organ failure), protozoan (cryptosporidiosis, diarrhea encaphilitis, giardiasis, amoebiasis) and fungal (candidiasis, blastomycosis, cryptococcusis, aspergilosis). These biological contaminants that cause several water-borne diseases can however be removed from water through physical (ultraviolet radiation, solar radiation and boiling) and chemical disinfection methods (chlorination, chloramination and ozonation). The aim of this paper was to review the microbial indicators and pathogenic microorganisms in water and wastewater. The paper also discussed the treatment strategies for microbial-contaminated water and wastewaters.

INFLUENCE OF ADDING THE BACILLUS KIND STAMM ON WORKING PARAMETERS OF WASTE WATER BUOLOGICAL TREATMENT

Research results of granular sludge application for waste water quality improvement and reducing charges for polluting discharges of hazardous substances into surface waters are given. There is considered the technology of waste water treatment based on the use of biochemical methods of processing. Methodology is given for biomass use with the selection of microorganisms for waste water treatment herewith the effectiveness of treatment plants (type 201) work is over the design standards.

The inhibitory effects of silver nanoparticles, silver ions, and silver chloride colloids on microbial growth

Emerging nanomaterials are of great concern to wastewater treatment utilities and the environment. The inhibitory effects of silver nanoparticles (Ag NPs) and other important Ag species on microbial growth were evaluated using extant respirometry and an automatic microtiter fluorescence assay. Using autotrophic nitrifying organisms from a well-controlled continuously operated bioreactor, Ag NPs (average size=14±6 nm), Ag + ions (AgNO 3), and AgCl colloids (average size=0.25 μm), all at 1 mg/L Ag, inhibited respiration by 86±3%, 42±7%, and 46±4%, respectively. Based on a prolonged microtiter assay, at about 0.5 mg/L Ag, the inhibitions on the growth of Escherichia coli PHL628-gfp by Ag NPs, Ag + ions, and AgCl colloids were 55±8%, 100%, and 66±6%, respectively. Cell membrane integrity was not compromised under the treatment of test Ag species by using a LIVE/DEAD Baclight™ bacterial viability assay. However, electron micrographs demonstrated that Ag NPs attached to the microbial cells, probably causing cell wall pitting. The results suggest that nitrifying bacteria are especially susceptible to inhibition by Ag NPs, and the accumulation of Ag NPs could have detrimental effects on the microorganisms in wastewater treatment.

Development of an advanced biological treatment system applied to the removal of nitrogen and phosphorus using the sludge ceramics

To develop a method of forming lake sediment into sludge ceramics with porosity and good biological adhesion for use as a medium for microorganisms in wastewater treatment, a study of the effects of forming conditions was conducted by adjusting the water content of sludge and compounding some additives. By adjusting the water content of the raw material at the kneading/pelletizing step to 40–42% and adding 3% waste glass to the raw materials to make up for the lack of flux, a sludge ceramic with a density in terms of specific gravity of saturated surface dry aggregate of about 1400 kg m −3 was formed. In addition, to develop a small-scale wastewater treatment system capable of removing nitrogen and phosphorus, a sludge ceramic was applied as a medium for biological filtration. The results indicated that the BOD removal nitrification rate were superior to those of conventional ceramic media, reached at 95.3% and 87.4%, respectively. The introduction of iron electrolysis resulted in high treatment performance achieving BOD levels of 10 mg L −1 or less, T-N of 10 mg L −1 or less and T-P of 1 mg L −1 or less.

Application of denitrifying microorganisms in waste water treatment

A continuous fixed-bed denitrification system operating with high capacity and 100% efficiency has been developed for laboratory scale experiments. The data required for stable operation were obtained by determination of the kinetic constants of the system.