Struvite recovery efficiency using flocculation in batch and continuous settling systems for ammonia removal of mining wastewater.

An approach to remove ammonia from mining wastewater is to precipitate ammonia into struvite, and flocculation was proved to enhance settling of struvite flocs. But the current literature fails to consider flocculent properties of struvite flocs, and previous studies focused only on small volumes. This study evaluates the effect of ammonia concentration and height on removal efficiency of struvite flocs in a batch system and compares removal efficiency of struvite flocs between a batch and a pilot-scale continuous settling process to evaluate the potential of using flocculation to recover struvite crystals as a stand-alone method. Removal efficiency of struvite using flocculation is evaluated depending on depth in a batch system for two different ammonia concentrations (45 and 90 ppm) and in a continuous system for different flowrates. It is shown that a higher concentration promotes flocculation and enhances settling velocities of struvite flocs. The difference between the batch and the continuous processes for the same removal efficiency was significantly higher from what has been reported in the literature: in the continuous process, 89% of struvite flocs have been recovered with a surface overflow rate (SOR) of 1.8 m.h-1 , whereas, for the same height, the same efficiency corresponds to SOR = 9 m.h-1 in the batch process. The fragile nature of struvite flocs is potentially responsible for such a difference. PRACTITIONER POINTS: Settling velocities of struvite flocs are highly dependant on concentration and depth. Removal efficiency are considerably higher with a batch settling process for the same surface overflow rate. Flocculation enable 89% of struvite fines to be recovered in a continuous settling process with a SOR of 1.8 m.hs-1 .

Collecting critically endangered cliff plants using a drone-based sampling manipulator.

Kaua'i, an island within the Hawai'i archipelago, is home of a unique flora that contains 250 single-island endemic plant species. Threats have led to a significant population decrease where 97% of these plant species are now listed as endangered, critically endangered, or extinct. Vertical cliff habitats on Kaua'i work as refugia to protect plants from their stressors. However, this habitat makes conservation work particularly difficult, forcing scientists, and botanists to use risky and time-consuming methods such as abseiling to access remote plant populations. Here we present the Mamba, the first aerial system capable of sampling plants on cliffs. This system is operated by two pilots and consists of an actively controlled platform suspended by a long cable under a lifting drone. Eleven otherwise inaccessible samples from five critically endangered species were collected during the first field trials on Kaua'i Island. The samples are currently surviving in nurseries, demonstrating that the Mamba can be used to complete the conservation life cycle for organisms located in difficult areas, from location to collection, then cultivation and outplanting.

Pulmonary hypertension subjects exhibit right ventricular transient exertional dilation during supine exercise stress echocardiography.

Pulmonary hypertension is a condition with high morbidity and mortality. Resting transthoracic echocardiography is a pivotal diagnostic and screening test for pulmonary hypertension. The role of exercise stress echocardiography in the diagnosis of pulmonary hypertension is not well-established. We studied right ventricular size changes during exercise using exercise stress echocardiography to assess differences between normal and pulmonary hypertension patients and evaluate test safety, feasibility, and reproducibility. Healthy control and pulmonary hypertension patients performed recumbent exercise using a bicycle ergometer. Experienced echocardiography sonographers recorded the following resting and peak exercise right ventricular parameters using the apical four chamber view: end-diastolic area; end-systolic area; mid-diameter; basal diameter; and longitudinal diameter. Two cardiologists masked to clinical information subsequently analyzed the recordings. Parameters with acceptable inter-rater reliability were analyzed for statistical differences between the normal and pulmonary hypertension patient groups and their association with pulmonary hypertension. We enrolled 38 healthy controls and 40 pulmonary hypertension patients. Exercise stress echocardiography testing was found to be safe and feasible. Right ventricular size parameters were all readily obtainable and all had acceptable inter-observer reliability except for right ventricular longitudinal diameter. During exercise, healthy controls demonstrated a decrease in right ventricular end-systolic area, end-diastolic area, mid-diameter, and basal diameter ( P < 0.05). Conversely, pulmonary hypertension patients demonstrated an increase in right ventricular end-systolic area, end-diastolic area, and mid-diameter ( P < 0.05). These changes were unaffected by multivariate corrections. The sensitivity for pulmonary hypertension of an increase in right ventricular size was 97.2% with a negative predictive value of 95.2%. The ROC C-statistic for increase in right ventricular size was 0.93. This transient exertional dilation (TED) of the right ventricle is observed in pulmonary hypertension patients but not in healthy controls. Recumbent right ventricular exercise stress echocardiography is a feasible and safe diagnostic test for pulmonary hypertension which warrants additional study.