Phosphorus recovery from a pilot-scale grate furnace: influencing factors beyond wet chemical leaching conditions.

Phosphorus is a non-renewable resource going to be exhausted in the future. Sewage sludge ash is a promising secondary raw material due to its high phosphorus content. In this work, the distribution of 19 elements in bottom and cyclone ashes from pilot-scale grate furnace have been monitored to determine the suitability for the phosphorus acid extraction. Moreover, the influence of some parameters beyond wet chemical leaching conditions were investigated. Experimental results showed that bottom ash presented lower contamination in comparison to cyclone ash and low co-dissolution of heavy metals (especially Cr, Pb and Ni), while high phosphorus extraction efficiencies (76-86%) were achieved. High Al content in the bottom ash (9.4%) negatively affected the phosphorus extraction efficiency as well as loss on ignition, while the particle size reduction was necessary for ensuring a suitable contact surface. The typology of precipitating agents did not strongly affect the phosphorus precipitation, while pH was the key parameter. At pH 3.5-5, phosphorus precipitation efficiencies higher than 90% were achieved, with a mean phosphorus content in the recovered material equal to 16-17%, comparable to commercial fertilizers. Instead, the co-precipitation of Fe and Al had a detrimental effect on the recovered material, indicating the need for additional treatments.

Metal-based flocculation to harvest microalgae: a look beyond separation efficiency.

Metal-based flocculants are commonly used for biomass harvesting in microalgae-based bio-refineries. Besides the high separation efficiency, additional aspects should be considered, related to the toxicity of metals for the algal biomass. Partitioning tests for commonly used flocculants (i.e., FeCl3 and Al2(SO4)3) showed that metals were mostly transferred to the solid phase with more than 95% of dosed metal ending up into the biomass, and low metal concentrations in the liquid effluent (lower than 0.4 mg L-1 for both metals), thus allowing for water reuse. Photosynthesis inhibition was tested on microalgae and microalgae-bacteria cultures, using a standardized photo-respirometry protocol in which typical concentrations used during coagulation-flocculation were assessed. Modelling dose-response curves, concentrations corresponding to 50% inhibition (IC50) were obtained, describing short-term effects. The obtained IC50 ranged from 13.7 to 28.3 mg Al L-1 for Al, and from 127.9 to 195.8 mg Fe L-1 for Fe, showing a higher toxicity for the Al-based flocculant. The recovery of photosynthesis inhibition was also quantified, to evaluate the possibility of reusing/recycling the harvested biomass. The results highlighted that the residual photosynthetic activities, evaluated after 1 h and 24 h of exposure to metals were partially recovered, especially for Al, passing from 67.3% to 94.6% activity, respectively, while long-term Fe effects were stronger (passing from 64.9% to 77.6% activity). A non-toxic flocculant (cationic starch) was finally tested, excluding potential effects due to biomass aggregation, as the reduction of photosynthetic activity only reached 3.4%, compared to control. Relevant modifications to the light availability and the optical properties of algal suspensions were assessed, identifying a strong effect of iron which caused an increase of the light absorbance up to approximately 40% at high Fe concentrations. Possible implications of dosing metallic flocculants in MBWWT processes are discussed, and suggestions are given to perform inhibition tests on flocculating chemicals.

A randomized controlled trial on the effects induced by robot-assisted and usual-care rehabilitation on upper limb muscle synergies in post-stroke subjects.

Muscle synergies are hypothesized to reflect connections among motoneurons in the spinal cord activated by central commands and sensory feedback. Robotic rehabilitation of upper limb in post-stroke subjects has shown promising results in terms of improvement of arm function and motor control achieved by reassembling muscle synergies into a set more similar to that of healthy people. However, in stroke survivors the potentially neurophysiological changes induced by robot-mediated learning versus usual care have not yet been investigated. We quantified upper limb motor deficits and the changes induced by rehabilitation in 32 post-stroke subjects through the movement analysis of two virtual untrained tasks of object placing and pronation. The sample analyzed in this study is part of a larger bi-center study and included all subjects who underwent kinematic analysis and were randomized into robot and usual care groups. Post-stroke subjects who followed robotic rehabilitation showed larger improvements in axial-to-proximal muscle synergies with respect to those who underwent usual care. This was associated to a significant improvement of the proximal kinematics. Both treatments had negative effects in muscle synergies controlling the distal district. This study supports the definition of new rehabilitative treatments for improving the neurophysiological recovery after stroke.

Antibiotic resistant bacteria in urban sewage: Role of full-scale wastewater treatment plants on environmental spreading.

The presence of antibiotic resistant bacteria (ARB) in wastewater was investigated and the role of wastewater treatment plants (WWTPs) in promoting or limiting antibiotic resistance was assessed. Escherichia coli (E. coli) and total heterotrophic bacteria (THB) resistance to ampicillin, chloramphenicol and tetracycline was monitored in three WWTPs located in Milan urban area (Italy), differing among them for the operating parameters of biological process, for the disinfection processes (based on sodium hypochlorite, UV radiation, peracetic acid) and for the discharge limits to be met. Wastewater was collected from three sampling points along the treatment sequence (WWTP influent, effluent from sand filtration, WWTP effluent). Antibiotic resistance to ampicillin was observed both for E. coli and for THB. Ampicillin resistant bacteria in the WWTP influents were 20-47% of E. coli and 16-25% of THB counts. A limited resistance to chloramphenicol was observed only for E. coli, while neither for E. coli nor for THB tetracycline resistance was observed. The biological treatment and sand filtration led to a decrease in the maximum percentage of ampicillin-resistant bacteria (20-29% for E. coli, 11-21% for THB). However, the conventionally adopted parameters did not seem adequate to support an interpretation of WWTP role in ARB spread. Peracetic acid was effective in selectively acting on antibiotic resistant THB, unlike UV radiation and sodium hypochlorite. The low counts of E. coli in WWTP final effluents in case of agricultural reuse did not allow to compare the effect of the different disinfection processes on antibiotic resistance.

Virtual Reality to Assess and Treat Lower Extremity Disorders in Post-stroke Patients.

INTRODUCTION: This article is part of the Focus Theme of Methods of Information in Medicine on "Methodologies, Models and Algorithms for Patients Rehabilitation". OBJECTIVES: To identify support of a virtual reality system in the kinematic assessment and physiotherapy approach to gait disorders in individuals with stroke. METHODS: We adapt Virtual Reality Rehabilitation System (VRRS), software widely used in the functional recovery of the upper limb, for its use on the lower limb of hemiplegic patients. Clinical scales have been used to relate them with the kinematic assessment provided by the system. A description of the use of reinforced feedback provided by the system on the recovery of deficits in several real cases in the field of physiotherapy is performed. Specific examples of functional tasks have been detailed, to be considered in creating intelligent health technologies to improve post-stroke gait. RESULTS: Both participants improved scores on the clinical scales, the kinematic parameters in leg stance on plegic lower extremity and walking speed > Minimally Clinically Important Difference (MCID). CONCLUSION: The use of the VRRS software attached to a motion tracking capture system showed their practical utility and safety in enriching physiotherapeutic assessment and treatment in post-stroke gait disorders.

Peracetic acid for secondary effluent disinfection: a comprehensive performance assessment.

The paper is a review of previous research on secondary effluent disinfection by peracetic acid (PAA) integrated with new data about the effect of a preliminary flash-mixing step. The process was studied at bench and pilot scale to assess its performance for discharge in surface water and agricultural reuse (target microorganisms: Escherichia coli and faecal coliform bacteria). The purposes of the research were: (1) determining PAA decay and disinfection kinetics as a function of operating parameters, (2) evaluating PAA suitability as a disinfectant, (3) assessing long-term disinfection efficiency, (4) investigating disinfected effluent biological toxicity on some aquatic indicator organisms (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum), (5) comparing PAA with conventional disinfectants (sodium hypochlorite, UV irradiation). PAA disinfection was capable of complying with Italian regulations on reuse (10 CFU/100 mL for E. coli) and was competitive with benchmarks. No regrowth phenomena were observed, as long as needed for agricultural reuse (29 h after disinfection), even at negligible concentrations of residual disinfectant. The toxic effect of PAA on the aquatic environment was due to the residual disinfectant in the water, rather than to chemical modification of the effluent.