Label-Free Darkfield-Based Technique to Assist in the Detection of <Emphasis Type="Italic">Giardia</Emphasis> Cysts     

Valdinei Luís Belini  Bárbara Luíza Souza Freitas  Lyda Patricia Sabogal-Paz  Nilson Branco  Regina Maura Bueno Franco 《Water, air, and soil pollution》2018,229(6):195

Giardia is a pathogenic protozoan that has caused giardiasis outbreaks worldwide, and this water-borne disease may occur due to faults in water supply and treatment systems. To support surveillance and control programs, the monitoring of this parasite is essential in water samples. Although Giardia cyst detection is usually based on standard light microscopy, the resulting low contrasted cysts together with a wide array of particles of comparable size to the target protozoan demands a high level of observer skill and experience, as well as a long time to process the individual samples. The visualization of this protozoan can be significantly improved by using staining procedures, e.g., Lugol’s iodine in brightfield or fluorescence-based methods such as fluorescence-isothiocyanate (FITC) and 4′,6-diamidino-2-phenylindole (DAPI). However, the significant costs make fluorescence microscopy difficult to be performed in less-developed countries. Accordingly, the present study evaluated the effectiveness of inexpensive darkfield (DF) setups to acquire higher contrasted images of unstained cyst samples as a direct and rapid method for monitoring protozoa. Two low-cost custom-made DF illumination modes, transmitted and reflected, were evaluated on a standard light microscope. Examination of purified Giardia cyst suspensions with both DF setups revealed a direct correlation between morphological appearance and uptake of DAPI. Images captured under transmitted illumination showed higher contrast and sharpness when compared to the reflected images. DF microscopy might provide a simple, direct, and inexpensive method for observing Giardia cysts, which shows basic aspects of their intracellular structure, although the applicability of the method to raw water concentrates remains to be demonstrated.  相似文献   

Pulp and Paper Mill Effluent Treated by Combining Coagulation-Flocculation-Sedimentation and Fenton Processes     

Mariana Grötzner  Emeline Melchiors  Luiz Henrique Schroeder  Alexandre Renato dos Santos  Kethlyn Ghellere Moscon  Marco Antonio de Andrade  Sérgio Henrique Saavedra Martinelli  Claudia Regina Xavier 《Water, air, and soil pollution》2018,229(11):364

Pulp and paper industries face serious environmental challenges, especially with regard to the conservation of water resources. Chemical thermal mechanical pulping (CTMP) is a process of pulping that combines chemical and mechanical pulping. This reduces the volume of water used in the process. But on the other hand, CTMP generates an effluent with high concentration of organic matter and is difficult to treat. This study evaluated the efficiency in the combination of physicochemical pretreatment by coagulation-flocculation-sedimentation (CFS) process and advanced oxidation process (AOP) by Fenton in sequence to treat CTMP effluent of a Brazilian industry. At first, the best treatment conditions for this type of effluent were determined. To evaluate the efficiency, pH, chemical oxygen demand, biochemical oxygen demand, total organic carbon, lignin contents, color, total phenolic contents, turbidity, and solids were measured before and after treatment. The acute toxicity on Daphnia magna was also determined. The treatment with CFS showed better results in the removal of solids and Fenton in the removal of recalcitrant compounds, such as lignin, demonstrating the need to use them in sequence. Combining CFS and Fenton to treat CTMP effluent allowed to achieve a removal efficiency of 95% for TOC, 61% for COD, and 76% for lignin contents.  相似文献