PULSE process: recovery of phosphorus from dried sewage sludge and removal of metals by solvent extraction.

Phosphorus (P) is an indispensable nutrient for agriculture. Recovery and recycling of phosphorus from waste streams is necessary to ensure a circular P economy and reduce dependence on disproportionately distributed mineral P resources. In this study, a new process called 'PULSE' is presented for the recovery of P from sewage sludge, which can handle high metal contents. The process involves drying of sludge prior to acidic leaching to overcome the challenge of solid-liquid separation at low pH and to reduce the overall material flows. Another key point of the process is the removal of metals using reactive extraction to obtain a high-quality product with good plant availability. Laboratory experiments were conducted to evaluate and select the best process options. A chemical equilibrium tool was developed to simulate the unit operations of the process for optimization. Dissolution of P from sludge depends on leaching pH and the fraction of inorganic P in the sludge. The maximum P leaching efficiency for the sludge used in the study was between 65 and 70%. Under the tested conditions, Fe, Cd, Cu, Hg, Pb, and Zn were successfully removed from the sludge leach liquor by reactive extraction. The recovered product has a nutrient mass fraction of about 51% that includes Ca, PO43-, Mg, and K. Pot trials confirmed that the agronomical efficiency of the product is comparable to that of triple superphosphate.

Pilot-scale phosphate recovery from wastewater to create a fertiliser product: An integrated assessment of adsorbent performance and quality.

Eutrophication and the predicted limited future availability of rock phosphate has triggered the increased development of phosphorus (P) recovery technologies, however, for remote regions, recovery solutions are still limited. Here, we report on a novel pilot-scale technology (FILTRAFLOTM-P reactor) to recover phosphate (PO43-) from wastewater effluent through a filtration/adsorption process in a rural setting. This unit employs enhanced gravitational filtration through adsorption media (here, a novel KOH deacetylated crab carapace based chitosan-calcite material (CCM)) with continuous self-backwashing. Trials were designed to assess how the FILTRAFLOTM-P unit would operate under 'real' conditions (both at low and high PO43- levels), and to ascertain the effectiveness of the adsorbent to recover phosphate from final effluent. High removal was achieved at low phosphate concentrations, bringing the residual effluent PO43- level below 1 mg/L (EU limit for sensitive water bodies), while phosphate was efficiently harvested (at more than 50%) at higher PO43- levels. Surface microprecipitation and inner-sphere complexation were postulated as the main PO43- adsorption mechanisms through XRD, XPS and EDX elemental mapping. Further, a quality assessment of the P-enriched CCM (which could be used as a potential soil amendment) was undertaken to consider elemental composition, microbiological assessment and quantification of organic micropollutants. Quality analysis indicated ∼2.5% P2O5 present, trace levels (well below legislative limits) of heavy metals and extremely low levels of organic pollutants (e.g., PCBs, pharmaceuticals). No detectable levels of target bacterial pathogens were observed. Pot trials showed that ryegrass cultivated with the addition of the CCM adsorbent achieved higher plant dry matter and P concentration when compared to unfertilised controls, with a slow-release kinetic pattern. This study showed that CCM used with the FILTRAFLOTM-P pilot reactor has high potential to recover phosphate from effluents and encourage resource recovery via bio-based management of waste.

Impact of time and phosphorus application rate on phosphorus bioavailability and efficiency of secondary fertilizers recovered from municipal wastewater.

Demand for phosphorus (P) resources other than non-renewable P rock has driven the development of several P recovery technologies from municipal wastewater treatment and directed recovery of P into valuable fertilizers (struvite, ash, iron phosphate, etc.). Although the bioavailability of novel secondary P fertilizers has been examined in previous studies, insufficient attention has been paid to defining optimal plant growth duration and monitoring conditions to assess the dynamic changes in P. Accordingly, five fertilizers recovered from municipal wastewater: two struvites (STRSL and STRLQ), two ashes (ASH1 and ASH2), and iron-phosphate pelletized sludge (FeP) using triple superphosphate (TSP) as a positive control and blank (zero P) as a negative control, were applied to P poor-sand at three P doses (equivalent to 30, 60, and 90 kg P2O5 ha-1). Fertilizer impact on perennial ryegrass (Lolium perenne) dry matter (DM) and P concentration were evaluated on a monthly basis for seven months. DM and relative agronomical efficiency (RAE) have shown the same trend between the fertilizers, but only at the lowest P dose (corresponding to 30 kg P2O5 ha-1). At higher P doses (60, and 90 kg P2O5 ha-1) the differences in DM and RAE among the fertilizers diminished. STRLQ, STRSL, ASH1 and FeP expressed a rather steady P release pattern, while ASH2 had a delay of four cuts and increase afterward. Monitoring the P uptake during four months of perennial ryegrass growth turned out to be the minimum, and seven months the optimum period for reaching the full capacity of the slow-release P fertilizers.

Treatment of displaced supracondylar humeral fractures in children by humero-ulnar external fixation.

PURPOSE: Humero-ulnar external fixation has been proposed to treat complex supracondylar humeral fractures in children. It facilitates fracture reduction and reduces the risk of ulnar nerve lesion, which can occur after cross pinning. METHODS: In a ten year period, 28 children have been operated on in our centre by humero-ulnar external fixation, for Lagrange-Rigault stages III and IV supracondylar humeral fractures. The data about fracture management and early follow-up were obtained from our medical database. The long-term evaluation was done at a minimum six months' follow-up. The range of motion and carrying angle measurements were classified according to Flynn. The final X-rays were evaluated for quality of reduction, presence of malunion, late infection signs, osteo-arthritis and myositis ossificans. The elbow function was evaluated by Mayo Elbow Performance Index (MEPI), Disabilities of the Arm, Shoulder and Hand (DASH) or modified DASH scores. RESULTS: The treatment was well tolerated by children and parents. There was no neurological complication related to the insertion of the pins, and no Volkmann syndrome. The median duration of external fixation was 33.5 days. Twelve patients were reviewed after a median follow-up duration of seven years (mean, 7.5 years; range, 3-21 years). One child had a refracture, three years after his original fracture, which was treated non-operatively. This case ended up in a cubitus varus deformity with a pronation deficit. All other patients had excellent clinical and radiological results. CONCLUSIONS: For the treatment of complex supracondylar humeral fractures in children, humero-ulnar external fixation is a good alternative to lateral or crossed pinning. The advantages are the ease to obtain the reduction, the absence of neurological risk to the ulnar nerve and the possibility to obtain good stabilisation of the fracture with moderate elbow flexion.

Natriuretic peptides in the evaluation of syncope in children and adolescents.

INTRODUCTION: Natriuretic peptides have an increasing role in assessing cardiovascular conditions. The number of papers addressing their role in the evaluation of children with syncope of unclear etiology is sparse. The aim of this study was to determine whether measuring atrial natriuretic peptide (ANP) and the inactive form, N-terminal prohormone of brain natriuretic peptide (NT-proBNP) concentration in children admitted due to differential diagnosis of syncope can be helpful in establishing the most probable cause of this condition. METHODS: The study included 88 patients between 9 and 18 years of age hospitalized due to syncope. The control group comprised 25 healthy children. In order to identify the cause of syncope, children with this condition were subjected to cardiologic and neurologic evaluation, and ANP and NT-proBNP concentrations were determined. RESULTS: The syncope group and the controls did not differ significantly in terms of natriuretic peptides concentrations. Similarly, no significant intergroup differences in natriuretic peptide concentrations were documented between children representing various types of response to the tilt test, and between the subgroups of patients with syncope of various origins. CONCLUSION: Analysis of natriuretic peptides concentrations in children with syncope does not result in unambiguous findings that would enable establishing accurate diagnosis.