Taguchi optimisation of the synthesis of vine-pruning-waste hydrochar as potential adsorbent for pesticides in water

This research aimed to synthesise an effective hydrochar adsorbent from vineyard pruning wastes to remove emerging contaminants as a potential valorisation product. The adsorption capacity of the hydrochar was optimised using the Taguchi method. Four synthesis variables were evaluated: hydrothermal reaction temperature, use of H3PO4 as a catalyst, number of acetone washes, and type of chemical cold activation. The simultaneous adsorption of five model pesticides (clothianidin (CTD), acetamiprid (ACE), 2,4-D, metalaxyl (MET), and atrazine (ATZ)) at an initial pH of 7 was studied. At optimum conditions, the hydrochar presented a total adsorption capacity of 22.7 μmol/g, representing a 2.7-fold improvement with respect to pristine hydrochar performance. High percentage removals were achieved for all pollutants (85 % CTD, 94 % ACE, 86 % MET, and 95 % ATZ) except for 2,4-D (4 %). This research provides a valuable reference for developing hydrochar adsorbents for pollution control and the valorisation of biomass wastes.

Hydroxyl radical and UV-induced reactions of bisphenol analogues in water: Kinetics, transformation products and estrogenic activity estimation

There is currently a concern about the endocrine-disrupting capacity of many bisphenol A substitutes, such as BPAF, BPAP, BPB, BPC, BPC-Cl, BPE, BPF, BPS and BPZ in natural waters. However, fundamental data (i.e., kinetics and mechanisms) about the performance of advanced oxidation processes and UV radiation for water decontamination are scarce. In this study, the removal of bisphenol A substitutes was evaluated by UV/H2O2 and UV treatments under neutral pH conditions. Reactivity of hydroxyl radical (·OH) with bisphenol analogues was studied by competition kinetics and their quantum yield was determined at 254 nm. Results revealed similar values of the second-order rate constants of ·OH with all bisphenols (5.89-14.1 × 109 M-1 s-1), as well as comparable values of the quantum yields (4.8-28.7 × 10-3 mol E-1), except for BPC-Cl. This compound showed a remarkably high quantum yield (4.7 × 10-1 mol E-1), which resulted in a removal higher than 60 % at typical UV disinfection doses (ca. 40 mJ cm-2). The transformation products formed by ·OH and UV-induced reactions were also assessed. Catechol and ortho-quinone derivatives were suggested as the main intermediates from the reaction of bisphenols with ·OH. Excluding BPC-Cl, the resulting photolysis products of bisphenols coincided with those from the ·OH reaction. A distinguished mechanism was proposed for the formation of the photolysis products of BPC-Cl, based on the favoured cleavage of the C-Cl bonds under UV irradiation. Phenanthrene-3,6-diol was suggested as main initial photolysis byproduct of BPC-Cl. Estrogenicity of bisphenols and detected intermediates was predicted using a Quantitative Structure-Activity Relationship (QSAR) approach. Certain byproducts produced during bisphenols reaction with ·OH, such as catechol derivatives, may exhibit estrogenic activity, as they were predicted as very strong binders. Similarly, all photolysis intermediates of BPC-Cl were predicted as very strong binders as well, suggesting that estrogenicity could persist after the treatment.

Spontaneous resolution of intracranial hypertension following radiotherapy for posterior parasagittal meningioma: About two cases and review of the literature

We report the cases of two patients who underwent normofractionated radiotherapy for evolutive asymptomatic parasagittal meningiomas. After completion of radiotherapy, both patients presented severe headache and vomiting episodes without papillar edema. We then decided a "wait-and-scan" strategy because of the slit-ventricles, and symptoms regressed spontaneously. MRI showed significant tumor regression a year after radiotherapy with a newly developed collateral venous drainage system in the first patient and a left, unusually large, superior anastomotic vein in the second. These clinical presentation and radiological evolution are compatible with venous stenosis caused by radiation-induced symptomatic edema, fading after the development of a collateral venous drainage system. The relation between pressure-related headaches and venous anatomy remains unclear in parasagittal meningiomas. These observations underline the importance of the study of venous anatomy when pressure-related headaches are suspected. Further clinical descriptions might help the clinicians to treat these patients' symptoms.

Reactions of bisphenol F and bisphenol S with ozone and hydroxyl radical: Kinetics and mechanisms

Bisphenol F (BPF) and bisphenol S (BPS) are the most employed substitutes of bisphenol A (BPA), after being restricted by legislation in different countries because of its endocrine disrupting behaviour. In the present work, a deep study was performed about the reactivity of BPF and BPS with ozone and hydroxyl radical. Firstly, the second order rate constants of ozone with the di-protonated, mono-protonated and deprotonated species of both bisphenols were determined to be 2.38 × 10⁴, 1.31 × 10⁹ and 1.43 × 10⁹ M^-1 s^-1 for BPF and 5.01, 2.82 × 10⁷ and 1.09 × 10⁹ M^-1 s^-1 for BPS. Then, the second order rate constants for the reaction of hydroxyl radical with BPF and BPS were established through UV/H₂O₂ and UV experiments at pH 7, resulting in the values of 8.60 × 10⁹ and 6.60 × 10⁹ M^-1 s^-1, respectively. Finally, a study regarding the transformation products (TPs) from the reaction of both bisphenols with molecular ozone and hydroxyl radical was also performed. Hydroxylation in the ortho position of the phenol rings was observed as main degradation pathway. Additionally, most of the TPs were accumulated over the reactions at relatively high oxidant doses.

Pesticide prioritization approaches and limitations in environmental monitoring studies: From Europe to Latin America and the Caribbean

Assessment and management of issues related to pesticide residues, such as environmental fate, monitoring and toxicity, are complex and, in many cases, require costly studies. The early establishment of a priority list of pesticides that should be monitored and assigned to a restricted-use policy is an important issue of post-registration Risk Assessment (RA). Various pesticide registration approaches have been adopted by different countries with those from Europe and the USA being the most popular, constituting the major prototypes for registration approaches in other countries. Adoption of pesticide registration and monitoring systems developed in Europe or USA by Latin American and Caribbean countries may underestimate factors affecting the environmental fate and toxicity of pesticides in their own countries. Incentive for this short review was the activities undertaken during the three KNOWPEC workshops held in Costa Rica, Argentina and Bolivia where European pesticide experts met Latin American experience in the form of Costa Rica's exceptional environmental conditions and ecology, Argentina's and Uruguay's soyisation and Bolivia's contrasting climate and agricultural zones. During the parallel activities of the workshop - including scientific presentations, field trips, interviews and meetings among European partners and pesticide stakeholders in Latin America, - the whole pesticide chain (import-export, trade, application, plant protection-efficacy, residues, monitoring, remediation and risk) was studied and clarified. Recently-published chemical prioritization studies were reviewed to consider their use as a tool to support risk assessments. Differences in regional practices are highlighted as regards to the establishment of RA or prioritization strategy in European and Latin American regimes. General guidance of establishing a cost-effective pesticide monitoring scheme in water bodies of Latin America and the Caribbean (LAC) is also proposed. Moreover, we summarize the most important factors that should be taken into consideration for prioritization approaches and categorization used in pesticide environmental monitoring studies. Consideration of current RA approaches and limitations, and pesticide prioritization exercises highlighted in this Commentary could assist in the management of pesticides in Latin America and Caribbean.

Sunlight and UVC-254 irradiation induced photodegradation of organophosphorus pesticide dichlorvos in aqueous matrices

Dichlorvos (DDVP) is an organophosphorus pesticide that has been classified as highly hazardous chemical by the World Health organization. In this study, the fate of the pesticide DDVP in natural water compartments was examined under simulated sunlight. Moreover, the effect of UV-254 irradiation on DDVP depletion was also studied. In deionized water, DDVP was photodegraded only in the presence of dissolved molecular oxygen. The photodegradation during the first 6 h of sunlight irradiation occurred with pseudo first-order kinetics, and the rate constants were 0.040 h^-1 at pH 7 and 0.064 h^-1 at pH 3. A reaction mechanism for the generation of reactive oxygen species (ROS) via DDVP photoabsorption was proposed. Humic acids (HA) played a double role as photosensitizer and inhibitor, observing an enhancement on DDVP photodegradation at low HA concentration (TOC = 2 mg L^-1). The depletion of DDVP under 254 nm UV irradiation was ascribed to direct photodegradation and oxygen mediated photoinduced reactions. Direct photodegradation of DDVP decreased with 254 nm irradiation reduction, highlighting the importance of radical mediated mechanisms at low irradiation doses. Based on LC/MS data, the main photoproducts under simulated solar light and UV-C irradiation were identified and potential reaction pathways were postulated. The three main identified products were o-methyl 2,2-dichlorovinyl phosphate, dichloroacetaldehyde and dimethylphosphate. Moreover, the toxicity of samples was evaluated along the irradiation exposure time using Microtox® assays. This study brings new insights into the role of oxygen in the photodegradation of DDVP and the induced and inhibition mechanisms involved in the presence of the humic acids in natural waters.

Priority pesticides abatement by advanced water technologies: The case of acetamiprid removal by ozonation

With the aim of exploring treatment alternatives for priority insecticide acetamiprid (ACMP) abatement, the removal of this compound from water by ozonation was studied for the first time, paying special attention to the kinetic, mechanistic and toxicological aspects of the process. The second order rate constants of reactions between ACMP and both molecular ozone (O₃) and hydroxyl radicals (OH) were determined to be 0.25M^-1s^-1 and 2.1·10⁹M^-1s^-1, respectively. On the basis of kinetic results, the degradation of ACMP during ozonation could be well-explained by the reactivity of this pesticide with OH. HPLC/MS analysis of the ozonated ACMP showed ACMP-N-desmethyl, 6-chloronicotinic acid, N'cyano-N-methyl acetamidine and N'-cyano acetamidine as the major transformation products (TPs), all of them formed through amine α carbon oxidation in combination with hydrolysis. Microtox bioassays revealed an increase in the toxicity of the medium during ACMP ozonation process, followed by a decrease to relatively low values. These changes could be attributed to the synergistic effects between TPs as well as to the presence of toxic intermediate aldehydes. Even though adopting strategies to further promote ozone decomposition to hydroxyl radicals appears to be essential, ozonation can be an effective treatment process for ACMP removal and associated toxicity abatement.

Exploring ozonation as treatment alternative for methiocarb and formed transformation products abatement

Despite the high toxicity and resistance to conventional water treatments exhibited by methiocarb (MC), there are no reports regarding the degradation of this priority pesticide by means of alternative purification technologies. In this work, the removal of MC by means of ozonation was studied for the first time, employing a multi-reactor methodology and neutral pH conditions. The second-order rate constants of MC reaction with molecular ozone (O₃) and formed hydroxyl radicals (OH·) were determined to be 1.7·10⁶ and 8.2·10⁹ M^-1 s^-1, respectively. During degradation experiments, direct ozone reaction was observed to effectively remove MC, but not its formed intermediates, whereas OH· could oxidize all species. The major identified TPs were methiocarb sulfoxide (MCX), methiocarb sulfoxide phenol (MCXP) and methiocarb sulfone phenol (MCNP), all of them formed through MC oxidation by O₃ or OH· in combination with hydrolysis. A toxicity assessment evidenced a strong dependence on MCX concentration, even at very low values. Despite the OH· capability to degrade MC and its main metabolites, the relative resistance of TPs towards ozone attack enlarged the oxidant dosage (2.5 mg O₃/mg DOC) necessary to achieve a relatively low toxicity of the medium. Even though ozonation could be a suitable technique for MC removal from water compartments, strategies aimed to further promote the indirect contribution of hydroxyl radicals during this process should be explored.

Role of oxygen and DOM in sunlight induced photodegradation of organophosphorous flame retardants in river water

The wide use of organophosphorous flame retardants (OPFR) and plasticizers causes a continuous release of large quantities into natural waters. One of the main contributors to micropollutants depletion in surface water is sunlight induced phototransformations. This study aims to elucidate whether alkyl, chloroalkyl and aryl organophosphorus flame retardants undergo phototransformations in river water. To perform the experiments, nine OPFR were subjected to natural sunlight, Xe lamp (simulated sunlight) and UV-C irradiations in ultra-pure Milli-Q water, Milli-Q water with humic acid and river water. Experiments demonstrated that OPFR achieve an important degree of photodegradation noticeable at long irradiation time, although direct photolysis did not account as the main photodegration mechanism. Results indicated that sunlight absorbing OPFR exhibited photosensitizing activity. The presence of azide in ultra- pure water inhibited some OPFR photodegration by singlet oxygen (¹O₂) scavenging, and the absence of dissolved oxygen significantly depleted most of OPFR removal. In the conditions studied, humic acid inhibited OPFR phototransformations, while river water enhanced their removal. Results from this study point out the need to further investigate the role of some OPFR as photosensitizers, which are important for fate and ecological risk assessment of flame retardants and other micropollutants in water.

Oestrogenicity assessment of s-triazines by-products during ozonation

The triazines are a group of herbicides with a wide range of uses. Atrazine is, in fact, one of the most used agricultural pesticides in the world. The terbuthylazine is applied as a substitute of atrazine in some countries of Europe since 2004, when the European Union announced a ban of atrazine because of ubiquitous water contamination. In this study, both atrazine and terbuthylazine were degraded by the ozone process to estimate the efficiency on pesticide removal in water, the intermediates formed and their potential oestrogenic activity using the yeast oestrogen screen (YES) test. Both pesticides were rapidly eliminated from the medium during ozonation (applied ozone dose 0.083 and 0.02 mmol O3 L(-1), respectively). The results show that both compounds generated similar by-products from ozone degradation. Moreover, significant oestrogenic activity was detected for both atrazine and terbuthylazine intermediates, during the first minutes of ozonation. The YES assay used in this study proved to be a sensitive tool in assessing trace amounts of oestrogenic chemicals, which can represent critical issues influencing the experimental results in environmental applications.

Pharmaceuticals and organic pollution mitigation in reclamation osmosis brines by UV/H2O2 and ozone

One significant disadvantage of using reverse osmosis (RO) for reclamation purposes is the need to dispose of the RO retentates. These retentates contain a high concentration of micropollutants, effluent organic matter (EfOM) and other inorganic constituents, which are recalcitrant to biological treatment and may impact the environment. The occurrence of 11 pharmaceuticals (concentrations ranging from 0.2 to 1.6 μg L(-1)) and their mitigation in RO retentates by a UV/H2O2 process and ozonation was studied using a wide range of oxidant dosages. Eleven pharmaceuticals were identified at. Initial observed kinetic constants (kobs) were calculated for the different pharmaceuticals. Other typical wastewater parameters were also monitored during the UV/H2O2 and ozonation reactions. The range for kobs was found to be 0.8-12.8L mmol O3(-1) and 9.7-29.9 L mmol H2O2(-1) for the ozonation and UV/H2O2 process, respectively. For ozonation, Atenolol, Carbamazepine, Codeine, Trimethoprim and Diclofenac showed the lowest initial kobs (in the order mentioned). Atenolol and Carbamazepine appeared as the most ozone resistant pharmaceuticals, exhibiting the lowest percentage of elimination at low ozone doses. On the other hand, despite the non-selectivity of HO, differences in the initial kobs were also observed during the UV/H2O2 process. Trimethoprim, Paroxetine and Sulfamethoxazole exhibited the lowest initial kobs values (in the order mentioned). Trimethoprim and Paroxetine also exhibited the lowest percentage removal when low H2O2 doses were assayed. The compounds that were identified as problematic during ozonation were more efficiently removed by the UV/H2O2 process. UV/H2O2 generally appeared to be a more efficient technology for removing pharmaceuticals from RO brines compared to ozonation.

Reverse osmosis concentrate treatment by chemical oxidation and moving bed biofilm processes

In the present work, four oxidation techniques were investigated (O3, O3/UV, H2O2/O3, O3/H2O2/UV) to pre-treat reverse osmosis (RO) concentrate before treatment in a moving-bed biofilm reactor (MBBR) system. Without previous oxidation, the MBBR was able to remove a small fraction of the chemical oxygen demand (COD) (5-20%) and dissolved organic carbon (DOC) (2-15%). When the concentrate was previously submitted to oxidation, DOC removal efficiencies in the MBBR increased to 40-55%. All the tested oxidation techniques improved concentrate biodegradability. The concentrate treated by the combined process (oxidation and MBBR) presented residual DOC and COD in the ranges of 6-12 and 25-41 mg L(-1), respectively. Nitrification of the RO concentrate, pre-treated by oxidation, was observed in the MBBR. Ammonium removal was comprised between 54 and 79%. The results indicate that the MBBR was effective for the treatment of the RO concentrate, previously submitted to oxidation, generating water with an improved quality.

Effects of ozone pre-treatment on diclofenac: intermediates, biodegradability and toxicity assessment

Diclofenac (DCF), a common analgesic, anti-arthritic and anti-rheumatic drug, is one of the most frequently detected compounds in water. This study deals with the degradation of diclofenac in aqueous solution by ozonation. Biodegradability (BOD(5)/COD ratio and Zahn-Wellens test), acute ecotoxicity and inhibition of activated sludge activity were determined in ozonated and non-ozonated samples. Liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) was used to identify the intermediates formed in 1 h of ozonation. Eighteen intermediates were identified by these techniques and a tentative degradation pathway for DCF ozonation is proposed. Experimental results show that ozone is efficient at removing DCF: >99% removal (starting from an initial concentration of 0.68 mmol L(-1)) was achieved after 30 min of ozonation (corresponding to an absorbed ozone dose of 0.22 g L(-1), which is 4.58 mmol L(-1)). However, only 24% of the substrate was mineralized after 1 h of ozonation. The biodegradability, respiration inhibition in activated sludge and acute toxicity tests demonstrate that ozonation promotes a more biocompatible effluent of waters containing DCF.

Combination of photo-Fenton and biological SBBR processes for sulfamethoxazole remediation

A combined strategy of a photo-Fenton pretreatment followed by a Sequencing Batch Biofilm Reactor (SBBR) was evaluated for total C and N removal from a synthetic wastewater containing 200 mg L(-1) of the antibiotic Sulfamethoxazole (SMX). Photo-Fenton reaction was performed with two different H2O2 concentrations (300 and 400 mg L(-1)) and 10 mg L(-1) of Fe2+. The pre-treated effluents with the antibiotic intermediates as sole carbon source, together with a nutrients solution, were used as feed for the biological reactor. The SBBR was operated under aerobic conditions to mineralize the organic carbon and the hydraulic retention time (HRT) was optimized down to 8 hours. Then, an anoxic denitrification stage of 24 hours of HRT was added right after the aerobic stage of the same duration in order to remove the NO3(-) generated along the chemical-biological treatment. TOC, COD and SMX concentrations together with O2 uptake rate (OUR) profiles were monitored in purpose of assessing the performance of the system. NO3(-), NH4+ and total N concentrations were analyzed to find out the fate of N contained in the initial SMX molecule. A start up strategy resulted in the correct formation of a biofilm over the volcanic support. The total TOC removals achieved with the combination of the chemical and the biological processes were 75.7 and 87.7% for the low and the high H2O2 concentration pretreatments respectively. Practically all N present in the SMX solution was eliminated in the SBBR when the aerobic-anoxic strategy was used.

Coupled photochemical-biological system to treat biorecalcitrant wastewater

The aim of the present work is to study a coupled system to treat biorecalcitrant wastewaters. The combination consists of an advanced oxidation process (AOP) named photo-Fenton (Ph-F), which is a photochemical treatment and a sequencing batch biofilter reactor (SBBR). The synthetic wastewater used to optimise this process is a solution of 200 ppm of 4-chlorophenol (4-CP). The first part of the work is the study of the biodegradability enhancement achieved by the photochemical process, measured as the ratio between the biochemical oxygen demand (BOD5) and the chemical oxygen demand (COD). The second step is the start-up and optimisation of the biological process. The results showed that it is necessary to severely treat the toxic solution (with 500 ppm of [H2O2]0) in order to achieve more than 90% of TOC removal in the whole process. The photochemical and biological treatments lasted 50 minutes and 24 hours, respectively.

Degradation of 2,4-dichlorophenol by combining photo-assisted Fenton reaction and biological treatment

The photo-Fenton reaction effect on the biodegradability improvement of 100 mg/L solution of 2,4-dichlorophenol (DCP) has been investigated. Biochemical oxygen demand (BOD) at 5 and 21 days, BODn/ chemical oxygen demand (COD) and BODn/total organic carbon (TOC) ratios, average oxidation state, and inhibition on activated sludge were monitored. For 50 mg/L hydrogen peroxide and 10 mg/L iron(II) initial concentrations and 40 minutes of reaction time in the photo-Fenton process, the biodegradability of the pretreated solution, measured as BOD5/COD ratio, was improved from 0 for the original DCP solution up to 0.18 (BOD21/COD = 0.24). At that point, all DCP was eliminated from the solution. To study the effect of the pretreatment step, the biological oxidation of pretreated solutions was tested in two semicontinuous stirred tank reactors, one operated with activated sludge and one with biomass acclimated to phenol. Results showed that more than 80% TOC removal could be obtained by codigestion of the pretreated solution with municipal wastewater. Total organic carbon removals of approximately 60% were also obtained when the sole carbon source for the aerobic reactors was the pretreated solution. The hydraulic retention times used in the bioreactors were of the same order of magnitude as those used at domestic wastewater treatment plants (i.e., between 12 and 24 hours). Kinetic studies based on pseudo-first-order kinetics have also been carried out. Constants were found to be in range 0.67 to 1.7 L x g total volatiles suspended solids(-1) x h(-1).

A comparative study of the advanced oxidation of 2,4-dichlorophenol

Advanced oxidation processes (AOPs) using UV, UV/H2O2, Fenton and photo-Fenton treatment were investigated at laboratory scale for aqueous solutions of 2,4-dichlorophenol (DCP). The effects on degradation of different reactant concentrations, irradiation time, temperature and pH were assessed. DCP removal, TOC mineralization, dechlorination and change in oxidation state were monitored. UV photolysis was less efficient for total DCP degradation than other AOPs. In contrast, photo-Fenton reaction in acidic conditions led to a higher DCP degradation in a short time. Sixty minutes of treatment were sufficient for 100% DCP removal with 75 mg l(-1) H2O2 and 10 mg l(-1) Fe(II) initial concentrations. In these conditions, a first-order degradation constant for DCP of 0.057 min(-1) was obtained.

Combining photo-Fenton process with biological sequencing batch reactor for 2,4-dichlorophenol degradation

The effect of the photo-Fenton process on biodegradability enhancement of 100 mg x L(-1) aqueous 2,4-dichlorophenol (2,4-DCP) solution has been investigated. An initial concentration of 65 mg x L(-1) H2O2 and 10 mg x L(-1) Fe (II) during 35 minutes of irradiation time was sufficient for total 2,4-DCP removal. At these working conditions, biodegradability, measured as BODS/COD ratio, was increased from 0 for the original solution up to 0.15. Biological oxidation of photo-Fenton pre-treated solutions was performed in a sequencing batch reactor (SBR). After 32 days of start-up, the reactor was fed with different pre-treated solutions and cycle duration was reduced progressively. TOC removal efficiencies in the SBR went from 30 up to 70%.

Contribution of the ozonation pre-treatment to the biodegradation of aqueous solutions of 2,4-dichlorophenol

The effect of ozonation on the biodegradability of 100-ppm aqueous solutions of 2,4-dichlorophenol has been investigated. BOD at 5, 10 and 21 days, BOD/COD and BOD/TOC ratios and the average oxidation state are presented. Biodegradability measured as BOD5/COD ratio was increased from 0 of the original solution to 0.25 at the moment of removing all the initial compound (corresponding to an ozone dose of 0.12 g L-1, 0.48 for BOD21/COD ratio). To test the effect of this pre-treatment, the biological oxidation of these pre-ozonated solutions was performed in two semi-continuous stirred tank reactors, one with non-acclimated sludge and one with acclimated-to-phenol sludge. The study showed that the TOC content of the pre-treated solution could be removed up to 68% by an aerobic biological treatment as well as co-digested with municipal wastewater (TOC removal up to 82%), with similar operating retention times to a municipal wastewater plant (12-24 h). Kinetic studies based on Monod model have also been carried out. Pseudo-first-order kinetic constants were found to be in the range of 0.5-0.8 L g TVSS-1 h-1.

Nitrification, denitrification and biological phosphorus removal in piggery wastewater using a sequencing batch reactor

Nutrients in piggery wastewater with high organic matter, nitrogen (N) and phosphorus (P) content were biologically removed in a sequencing batch reactor (SBR) with anaerobic, aerobic and anoxic stages. The SBR was operated with 3 cycles/day, temperature 30 degrees C, sludge retention time (SRT) 1 day and hydraulic retention time (HRT) 11 days. With a wastewater containing 1500 mg/l ammonium and 144 mg/l phosphate, a removal efficiency of 99.7% for nitrogen and 97.3% for phosphate was obtained. Experiments set up to evaluate the effect of temperature on the process showed that it should be run at temperatures higher than 16 degrees C to obtain good removals (> 95%). Batch tests (ammonia utilization rate, nitrogen utilization rate and oxygen utilization rate) proved to be good tools to evaluate heterotrophic and autotrophic biomass activity. The SBR proved to be a very flexible tool, and was particularly suitable for the treatment of piggery wastewater, characterized by high nutrient content and by frequent changes in composition and therefore affecting process conditions.

The effects of bone morphogenetic protein 2 and 4 (BMP2 and BMP4) on gap junctions during neurodevelopment

Nervous system deficits account for the third largest group of fatal birth defects (after heart and respiratory problems) in North America. Although considerable advance has been made in neuroscience research, the early events involved in neurogenesis remain to be elucidated. More specifically, the effects of signaling molecules on intercellular communication during neurodevelopment have not yet been studied. The development of the central nervous system is regulated, at least in part, by signaling molecules such as bone morphogenetic proteins (BMPs). In this study, we have used the embryonal mouse P19 cell line to examine the effects of BMP2 and BMP4 on gap junctional communication as well as neuronal and astrocytic differentiation. The undifferentiated P19 cells show high levels of the gap junction protein, connexin43 (Cx43), and functional intercellular coupling. However, Cx43 expression and dye coupling decrease as these cells differentiate into neurons and astrocytes. In contrast, cells treated with BMP2 or BMP4 lose their capacity to differentiate into neurons but not astrocytes, while they maintain extensive gap junctional communication. The very few neurons that remain in the BMP-treated cultures are coupled (a characteristic not seen in the control neurons). Together, our data suggest that BMPs may play a critical role in morphogenesis of P19 cells while they affect gap junctions.