Évolution des acides aminés et de la matière organique dissoute dans une filière de production d'eau potable: Corrélations avec le carbone organique dissous biodégradable et le potentiel de demande en chlore à long terme

Le suivi de la matière organique totale (COD) et spécifique (substances humiques et principalement acides aminés dissous totaux) dans les eaux d'une filière de production d'eau potable a mis en évidence des abattements moyens dans l'eau traitée représentant 40 % du COD et 0 à 75 % des acides aminés. Parallèlement, le potentiel de demande en chlore à long terme est diminué de près de 70 %, alors que la fraction biodégradable connait une élimination de l'ordre de 50 %.Aucune corrélation directe n'a pu être mise en évidence entre les teneurs en acides aminés et la valeur du carbone organique dissous biodégradable (CODB) et de la demande en chlore des eaux brutes ou en cours de traitement. Cependant, compte tenu des teneurs en acides aminés dissous totaux quantifiées dans les eaux traitées de l'usine, leur participation peut être estimée entre 5 et 23 % du potentiel de demande en chlore et entre 5 et 25 % du CODB.La matière organique analysée spécifiquement dans le cadre de cette étude (substances humiques et acides aminés dissous totaux), représente 20 à 35 % du COD des eaux en fin de filière, et la présence de ces composés organiques serait responsable d'une part notable de la demande en chlore à long terme des eaux (40 à 60 %).Dissolved organic compounds (dissolved organic carbon (DOC), biodegradable dissolved organic carbon (BDOC), total amino acids and humic substances) and their chlorine demand were analyzed monthly at different steps of the water treatment plant of Méry-sur-Oise (Paris, France, 270 000 m3/d, Fig. 1).Total dissolved amino acids were determined by HPLC analysis with fluorimetric detection after hydrolysis of combined amino acids (proteins, polypeptides) by hydrochloric acid (DOSSIER BERNE et al., 1994 a); the separation of 17 amino acids was performed after orthophthaldialdehyde (OPA) pre-column derivatization. Humic substances were determined according to the method developed by THURMAN and MALCOLM (1981), by gravity feeding XAD-8 resins with acidified samples. The humic fraction was expressed as the difference between DOC before and after passage through the column. The method developped by JORET and LÉVI (1986) using a biologically active sand inoculum was used for the determination of BDOC.For the determination of chlorine consumption, the kinetic model described by JADAS- HÉCART et al. (1992) was used; it takes into account the long-term chlorine demand in terms of potential demand. This method was automated (DOSSIER BERNE et al., 1994 b) and computer-assisted. The chlorine dose was chosen depending on the DOC value and on the N-NH4+ content of the water; the applied dose was: 3 mg Cl2/mg DOC + 10 mg Cl2/mg N-NH4+. Chlorine determination was performed automatically by the spectrophotometric N, N-diethylphenylene-1,4-diamine (DPD) method.In raw water, DOC values may reach 5.6 to 6.5 mg C l-¹ during the cold season, but the average yield of elimination was generally close to 40 % (Fig. 2). The biodegradable fraction of the organic carbon (BDOC), which represents 25 to 50 % of the DOC in the raw water, was partially removed in the plant and the residual concentration in treated water varied between 0.4 to 1.8 mg C l-¹ (Fig. 2). A transitory increase in the BDOC values was generally observed during the ozonation step; it reached 0.2 to 0.5 mg C l-¹ (Figs. 6 and 7).Whatever the period of the year, extracted humic substances constituted about 50 % of the DOC found in raw water (Fig. 3). This hydrophobic fraction was significantly removed in the treatment plant reducing the proportion of humic substances in the DOC of treated water to 16 - 23 % (Figs. 3, 6 and 7). The concentrations of total dissolved amino acids ranged from 100 to 260 µg l-¹ C in raw water and from 50 to 150 µg l-¹ C in produced water (Fig. 4); the main part of this elimination occurred during the clarification step (Figs. 6 and 7). No important seasonal variations could be observed for chlorine demand (Fig. 5); its removal occurred at each step of treatment and the average global elimination by the plant was of the order of 70 % (Figs. 6 and 7).On account of the low concentrations of amino acids, no direct relation could be shown between amino acid concentrations and the respective values of BDOC or of chlorine demand potential (Figs. 9 and 10). With regards to BDOC and chlorine demand potential, no correlation could be shown between these two parameters either (Fig. 8). However, it was possible to calculate the contribution of specific classes of dissolved organic compounds to chlorine demand and to BDOC. This calculation is based: i) on the concentrations of humic substances and amino acids measured during the monthly experiments at each point of the treatment plant, ii) on bibliographic data concerning the contribution to BDOC (biodegradability) and chlorine consumption of a large variety of model molecules (free or combined amino acids, aquatic humic substances). The results obtained in this way are reported in Table 3 for the treated water of the M?ry sur Oise plant. These results indicate that the small amounts of total dissolved amino acids present in treated water may account for 5 to 25 % of the BDOC value and for 5 to 23 % of the total chlorine demand potential. With regard to humic substances, their biodegradability was assumed to be very low but their contribution to the chlorine demand of the treated water was estimated between 10 to 40 %, whereas their DOC contribution ranges from 16 to 35 %. As a consequence, both amino acids and humic substances could account for 40 to 60 % to the chlorine demand of treated water. A special point should be noticed for total amino acids: their contribution to the DOC values of treated water was only 2 to 7 %, but they may account for a larger proportion of BDOC or chlorine demand potential (5 to 25 %)

Treatment and long-term outcome in primary nephrogenic diabetes insipidus

Background: Primary nephrogenic diabetes insipidus (NDI) is a rare disorder and little is known about treatment practices and long-term outcome. Methods: Paediatric and adult nephrologists contacted through European professional organizations entered data in an online form. Results: Data were collected on 315 patients (22 countries, male 84%, adults 35%). Mutation testing had been performed in 270 (86%); pathogenic variants were identified in 258 (96%). The median (range) age at diagnosis was 0.6 (0.0–60) years and at last follow-up 14.0 (0.1–70) years. In adults, height was normal with a mean (standard deviation) score of −0.39 (±1.0), yet there was increased prevalence of obesity (body mass index >30 kg/m2; 41% versus 16% European average; P < 0.001). There was also increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (32%) and adults (48%). Evidence of flow uropathy was present in 38%. A higher proportion of children than adults (85% versus 54%; P < 0.001) received medications to reduce urine output. Patients ≥25 years were less likely to have a university degree than the European average (21% versus 35%; P = 0.003) but full-time employment was similar. Mental health problems, predominantly attention-deficit hyperactivity disorder (16%), were reported in 36% of patients. Conclusion: This large NDI cohort shows an overall favourable outcome with normal adult height and only mild to moderate CKD in most. Yet, while full-time employment was similar to the European average, educational achievement was lower, and more than half had urological and/or mental health problems

Variability of diagnostic criteria and treatment of idiopathic nephrotic syndrome across European countries

The aim of the surveys conducted by the Idiopathic Nephrotic Syndrome Working Group of the ESPN was to study the possible variability of treatment in Europe at different stages of the disease by means of questionnaires sent to members of the Working Group. Four surveys have been completed: treatment of the first flare, treatment of the first relapse and the issue of steroid dependency, use of rituximab, and the management of steroid-resistant patients. A uniform treatment of the first flare was applied in only three countries, and ten additional centers have adopted one of the three main protocols. Reported treatment of the first relapse was relatively uniform, whereas the use of additional immunosuppressants in steroid dependency was widely variable. Rituximab had already been used in hundreds of patients, although the formal evidence of efficiency in steroid dependency was relatively recent at the time of the survey. The definition of steroid resistance was variable in the European centers, but strikingly, the first-line treatment was uniform throughout the centers and included the combination of prednisone plus calcineurin antagonists. Conclusion: The variability in the approach of idiopathic nephrotic syndrome is unexpectedly large and affects treatment of the first flare, strategies in the case of steroid dependency, as well as the definitions of steroid resistance.What is Known:• Steroids and immunosuppressants are the universal treatment of idiopathic nephrotic syndrome.What is New:• The variability of treatments and strategy of treatment in European centers of pediatric nephrology

Severe neurological outcomes after very early bilateral nephrectomies in patients with autosomal recessive polycystic kidney disease (ARPKD)

To test the association between bilateral nephrectomies in patients with autosomal recessive polycystic kidney disease (ARPKD) and long-term clinical outcome and to identify risk factors for severe outcomes, a dataset comprising 504 patients from the international registry study ARegPKD was analyzed for characteristics and complications of patients with very early (� 3 months; VEBNE) and early (4�15 months; EBNE) bilateral nephrectomies. Patients with very early dialysis (VED, onset � 3 months) without bilateral nephrectomies and patients with total kidney volumes (TKV) comparable to VEBNE infants served as additional control groups. We identified 19 children with VEBNE, 9 with EBNE, 12 with VED and 11 in the TKV control group. VEBNE patients suffered more frequently from severe neurological complications in comparison to all control patients. Very early bilateral nephrectomies and documentation of severe hypotensive episodes were independent risk factors for severe neurological complications. Bilateral nephrectomies within the first 3 months of life are associated with a risk of severe neurological complications later in life. Our data support a very cautious indication of very early bilateral nephrectomies in ARPKD, especially in patients with residual kidney function, and emphasize the importance of avoiding severe hypotensive episodes in this at-risk cohort. © 2020, The Author(s)

The Marks We Make de Robert & Shana ParkeHarrison

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Kinetics of Chlorination of Benzophenone-3 in the Presence of Bromide and Ammonia

International audienceThe aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia