Effect of floating treatment wetland coverage ratio and operating parameters on nitrogen removal: toward design optimization.

Floating treatment wetlands (FTWs) have the potential to improve the quality of wastewater discharges, yet design basics are unavailable to size these systems. This study investigates the effect of FTWs' coverage ratio and hydraulic retention time on agri-food wastewater treatment. This was studied in a pilot-scale experiment comprising four lagoons (6.5 m3 each) fed with real effluent from an existing tertiary treatment lagoon. An evaluation of FTW of different sizes (L24, L48, and L72 representing 24, 48, and 72% of pilot lagoons surface areas) and a control, L0 (without FTW), was performed over 16 months. Overall, L72 and L48 moderately improved total nitrogen (TN) mass removal compared to L0 (p < 0.05), while L24 exhibited similar TN mass removal (p = 0.196). The highest improvement was observed for L72, exhibiting up to 55% (mean of 13%) greater N mass removal than the control. The net increase in TN removal by FTWs was mainly related to denitrification, promoted by decreasing dissolved oxygen for increasing FTW coverage ratio. Residence time, temperature, and dissolved oxygen were the main parameters driving TN removal by FTWs. Retrofitting existing lagoons with FTW can facilitate N retrieval through plant harvesting, thereby reducing N remobilization from sediment (common in conventional lagoons).

Characterizing the multi-dimensional reaction dynamics of dihalomethanes using XUV-induced Coulomb explosion imaging.

Site-selective probing of iodine 4d orbitals at 13.1 nm was used to characterize the photolysis of CH2I2 and CH2BrI initiated at 202.5 nm. Time-dependent fragment ion momenta were recorded using Coulomb explosion imaging mass spectrometry and used to determine the structural dynamics of the dissociating molecules. Correlations between these fragment momenta, as well as the onset times of electron transfer reactions between them, indicate that each molecule can undergo neutral three-body photolysis. For CH2I2, the structural evolution of the neutral molecule was simultaneously characterized along the C-I and I-C-I coordinates, demonstrating the sensitivity of these measurements to nuclear motion along multiple degrees of freedom.

Prevalence of parenthood in wheelchair-dependent persons with long-term spinal cord injury in the Netherlands.

STUDY DESIGN: Multicenter  cross-sectional study. OBJECTIVES: To determine the prevalence of parenthood in long-term wheelchair-dependent persons who sustained a spinal cord injury (SCI) during their reproductive years. Secondary aims were to (1) explore patient-specific and disease-related factors associated with parenthood after SCI; and (2) quantify fertility aids used by men with SCI. SETTING: Eight specialized SCI rehabilitation centers in the Netherlands. METHODS: Questionnaires and physical examination were applied in 255 persons with SCI. Prevalence rates of parenthood among the general Dutch population were used for comparison. Logistic regression analyses were used to explore factors associated with parenthood after SCI. RESULTS: Prevalence of parenthood in SCI was 50% in men and 45% in women, which was significantly (P < 0.05) lower than rates in the general population (74% in men and 81% in women). Among the parents with SCI, most (66% of males and 72% of females) of them had children after SCI. Parenting children after SCI was associated with partnership (OR = 14.5, P < .001 [men]; OR = 3.7, P = .05 [women]), normal micturition (OR = 4.9, P = .02 [men]), incomplete lesion (OR = 5.4, P = .03 [women]), and paraplegia (OR = 7.3, P = .02 [women]). The most frequently used methods for ejaculation and fertilization were electroejaculation (29%) and intracytoplasmatic sperm injection (23%). CONCLUSIONS: Prevalence of parenthood in SCI persons is low. However, half of the persons with SCI do become parents, with most doing so following SCI. Demographic and disease-related factors may contribute to this.