Novel extended hybrid tool for real time control and practically support decisions to reduce GHG emissions in full scale wastewater treatment plants.

In this paper, a novel methodology and extended hybrid model for the real time control, prediction and reduction of direct emissions of greenhouse gases (GHGs) from wastewater treatment plants (WWTPs) is proposed to overcome the lack of long-term data availability in several full-scale case studies. A mechanistic model (MCM) and a machine learning (ML) model are combined to real time control, predict the emissions of nitrous oxide (N2O) and carbon dioxide (CO2) as well as effluent quality (COD - chemical oxygen demand, NH4-N - ammonia, NO3-N - nitrate) in activated sludge method. For methane (CH4), using the MCM model, predictions are performed on the input data (VFA, CODs for aerobic and anaerobic compartments) to the MLM model. Additionally, scenarios were analyzed to assess and reduce the GHGs emissions related to the biological processes. A real WWTP, with a population equivalent (PE) of 125,000, was studied for the validation of the hybrid model. A global sensitivity analysis (GSA) of the MCM and a ML model were implemented to assess GHGs emission mechanisms the biological reactor. Finally, an early warning tool for the prediction of GHGs errors was implemented to assess the accuracy and the reliability of the proposed algorithm. The results could support the wastewater treatment plant operators to evaluate possible mitigation scenarios (MS) that can reduce direct GHG emissions from WWTPs by up to 21%, while maintaining the final quality standard of the treated effluent.

Demo-scale up-flow anaerobic sludge blanket reactor coupled with hybrid constructed wetlands for energy-carbon efficient agricultural wastewater reuse in decentralized scenarios.

The impact of climate change on water availability and quality has affected agricultural irrigation. The use of treated wastewater can alleviate water in agriculture. Nevertheless, it is imperative to ensure proper treatment of wastewater before reuse, in compliance with current regulations of this practice. In decentralized agricultural scenarios, the lack of adequate treatment facilities poses a challenge in providing treated wastewater for irrigation. Hence, there is a critical need to develop and implement innovative, feasible, and sustainable treatment solutions to secure the use of this alternative water source. This study proposes the integration of intensive treatment solutions and natural treatment systems, specifically, the combination of up-flow anaerobic sludge blanket reactor (UASB), anaerobic membrane bioreactor (AnMBR), constructed wetlands (CWs), and ultraviolet (UV) disinfection. For this purpose, a novel demo-scale plant was designed, constructed and implemented to test wastewater treatment and evaluate the capability of the proposed system to provide an effluent with a quality in compliance with the current European wastewater reuse regulatory framework. In addition, carbon-sequestration and energy analyses were conducted to assess the sustainability of the proposed treatment approach. This research confirmed that UASB rector can be employed for biogas production (2.5 L h-1) and energy recovery from organic matter degradation, but its effluent requires further treatment steps to be reused in agricultural irrigation. The AnMBR effluent complied with class A standards for E. coli, boasting a concentration of 0 CFU 100 mL-1, and nearly negligible TSS levels. However, further reduction of BOD5 (35 mg L-1) is required to reach water quality class A. CWs efficiently produced effluent with BOD5 below 10 mg L-1 and TSS close to 0 mg L-1, making it suitable for water reuse and meeting class A standards. Furthermore, CWs demonstrated significantly higher energy efficiency compared to intensive treatment systems. Nonetheless, the inclusion of a UV disinfection unit after CWs was required to attain water class B standards.

Tool for fast assessment of stormwater flood volumes for urban catchment: A machine learning approach.

Specific flood volume is an important criterion for evaluating the performance of sewer networks. Currently, mechanistic models - MCMs (e.g., SWMM) are usually used for its prediction, but they require the collection of detailed information about the characteristics of the catchment and sewer network, which can be difficult to obtain, and the process of model calibration is a complex task. This paper presents a methodology for developing simulators to predict specific flood volume using machine learning methods (DNN - Deep Neural Network, GAM - Generalized Additive Model). The results of Sobol index calculations using the GSA method were used to select the ML model as an alternative to the MCM model. It was shown that the DNN model can be used for flood prediction, for which high agreement was obtained between the results of GSA calculations for rainfall data, catchment and sewer network characteristics, and calibrated SWMM parameters describing land use and sewer retention. Regression relationships (polynomials and exponential functions) were determined between Sobol indices (retention depth of impervious area, correction factor of impervious area, Manning's roughness coefficient of sewers) and sewer network characteristics (unit density of sewers, retention factor - the downstream and upstream of retention ratio) obtaining R2 = 0. 55-0.78. The feasibility of predicting sewer network flooding and modernization with the DNN model using a limited range of input data compared to the SWMM was shown. The developed model can be applied to the management of urban catchments with limited access to data and at the stage of urban planning.

Polyethylene pipes exposed to chlorine dioxide in drinking water supply system: A critical review of degradation mechanisms and accelerated aging methods.

Polyethylene (PE) pipes have been widely used in drinking water distribution systems across the world. In many cases, chlorine dioxide (ClO2) is used to maintain a residual disinfectant concentration in potable water. Practical experiences have shown that the lifetime of PE pipes is significantly reduced due to exposure to drinking water with ClO2. Recently, many companies have proposed new PE pipes with a modified formulation, which are more resistant to chlorine dioxide. However, a standardized test method for evaluating the long-term performances of PE pipes is still missing. This literature review was performed to provide a description of chlorine dioxide uses and degradation mechanisms of polyethylene pipes in real water distribution systems. Current accelerated aging methods to evaluate long-term performances of PE pipes exposed to ClO2 are described and discussed along with the common technics used to characterize the specimens. Accelerate aging methods can be distinguished in immersion aging tests and pressurized pipe loop tests. Wide ranges of operational conditions (chlorine dioxide concentration, water pressure, water temperature, etc.) are applied, resulting in a great variety of results. It was concluded that pressurized looping tests applying semi-realistic operational conditions could better replicate the aging mechanisms occurring in service. Despite this, the acceleration and the evaluation of the long-term performance are still difficult to determine precisely. Further experimentation is needed to correlate chemical-mechanical characterization parameters of PE pipes with their lifetime in service.

Performance of graphene and traditional soil improvers in limiting nutrients and heavy metals leaching from a sandy Calcisol.

Given the large amount of Graphene produced in the last years, there is the need to introduce this new material into a green and circular economy loop. In this study, for the first time, the fate of nutrients and heavy metals in a sandy Calcisol amended with Graphene was monitored and compared to other traditional improvers such as Compost, Zeolites, and Biochar. This was performed via saturated and unsaturated columns' experiments with two different fertilization regimes: one with NPK fertilizer and one with an innovative fertigation water (FW) produced from a pilot wastewater treatment plant. The breakthrough curves of each nutrient and heavy metal were analysed to understand the main processes occurring in saturated and unsaturated conditions, comparing the columns amended with the improvers versus the unamended Controls. Mass balances for each nutrient and heavy metal were developed to infer whether the different soil improvers were effective in minimizing leaching. Graphene, for most cases, behaved as the Control in nutrients' leaching for all the saturated and unsaturated experiments, both with NPK and FW. Biochar increased EC, K+, and pH of the leaching water, which could be an issue for the growth of some plants. Compost increased NO3- leaching in all the experiments. Zeolites showed the best N compounds retention, but great PO43- leaching in saturated conditions. Heavy metals leachates were analysed only for unsaturated columns (as more representative of field conditions) and found at concentrations well below the limits suggested by the U.S. Environmental Protection Agency. Overall, Graphene performed well in minimizing nutrients and heavy metals leaching, respect to classical improvers. This study is a starting point for field studies that will be critical to have a clear understanding of how Graphene behaves in the environment.

Sleep Disturbances in Children Affected by Autism Spectrum Disorder.

BACKGROUND: Sleep disturbances are common in children affected by Autism Spectrum Disorder (ASD). The aim of our study was to describe sleep characteristics and disturbances in children with ASD, to evaluate possible related factors, and to assess parental stress. METHODS: Hundred children with a diagnosis of ASD (mean age: 66.7 months, SD: 27.4, range: 24.7-152.1 months, n = 79 males) were included in the study. We collected data on sociodemographic, clinical, genetic and instrumental variables as well as comorbid conditions. Parents filled out the Questionnaire on sleep behavior in the first years of life, the BEARS questionnaire, and the Parenting Stress Index Short Form. From the analysis on sleep characteristics, we excluded 25 children treated with melatonin. RESULTS: Fifty-seven (57%) out of 100 children met the criteria for insomnia. Sleep disorders were associated with developmental or cognitive delay, emotional and behavioral problems (such as anxiety problems and aggressive behaviors) and absence of strategies for inducing sleep after nocturnal awakenings. From parents' reports, sleep disorders had diurnal repercussions on their offspring; however, we found no statistical correlation between disturbances and family stress. Also, no significant correlation was found between sleep disturbances and epilepsy. Finally, a statistical correlation was found between the regular intake of melatonin and the resolution of insomnia. CONCLUSIONS: Multifactorial variables may be associated to insomnia that could have an impact on the children' behavior. Clinicians need to be aware of the value of screening for sleep disturbance in children with ASD to integrate sleep interventions in the treatment plan.

Validation of an evidence-based methodology to support regional carbon footprint assessment and decarbonisation of wastewater treatment service in Italy.

In this paper, a new regional methodological approach for determining direct and indirect emissions from wastewater treatment plants (WWTPs) is proposed. Additionally, an entire territorial wastewater treatment service located in the northern Italy and serving 411,484 PE was assessed. The most accurate emission factor identification is presented using appropriate on-site measurements, monitoring different aerated operational units and sampling several streams in 12 relevant WWTPs of different treatment capacities, ranging from 3000 to 73,000 PE. Dissolved greenhouse gas (GHG) concentrations from 0.2 to 24 mgN2O/L, 0.1 to 1 mgCH4/L and 1.8 to 52 mgCO2/L in effluent flows were detected. Specific carbon footprints resulted in the emissions of 0.04-0.20 tonCO2eq/PE/y, varying as per the size of the plants. The most impactful categories were identified for indirect emissions, associated with dissolved GHGs discharged in the surface water body and due to energy consumption, which accounted for 13-70% and 10-40%, respectively. The overall territorial carbon footprint of the wastewater treatment service was also quantified to provide evidence-based decision support system (DSS) and prepare systemic mitigation strategies.

Brine treatment technologies towards minimum/zero liquid discharge and resource recovery: State of the art and techno-economic assessment.

In the framework of minimum liquid discharge (MLD) or zero liquid discharge (ZLD), sustainable brine management can be achieved via appropriate hybrid treatment technologies that provide water reuse, resource recovery, energy recovery and even freshwater production. This paper reviews the state of the art brine treatment technologies targeting MLD/ZLD and resource recovery and highlights their advantages and limitations. The right combination of treatment processes can add a high value to the brine management and shift the focus from removal to recovery and reuse point and help to adopt a more circular economy approach. ZLD technologies targets 100% water recovery using both membrane- and thermal-based technologies, while they are often hindered by high cost and intensive energy requirement. Meanwhile, the recovery of salts and other resources can partially compensate the operation cost of ZLD processes. MLD is a promising option that achieves up to 95% water recovery by using mainly membrane-based technologies. At this point, feasibility assessment is important to assess the environmental and economic sound of technologies. In the second part, we provide a techno-economic assessment of the most common technologies to provide possible benefits on a desalination plant. In the latter sections, innovative brine treatment schemes are discussed aiming MLD/ZLD, while resource recovery from brine and possible valorization routes of the recovered materials are highlighted to help to reduce the overall costs of the plants and to reach the targets of circular economy.

Monitoring of cyanobacterial blooms and assessing polymer-enhanced microfiltration and ultrafiltration for microcystin removal in an Italian drinking water treatment plant.

The water intake of a drinking water treatment plant (DWTP) in Central Italy was monitored over six bloom seasons for cyanotoxin severity, which supplies drinking water from an oligo-mesotrophic lake with microcystin levels up to 10.3 µg/L. The historical data showed that the water temperature did not show extreme/large seasonal variation and it was not correlated either with cyanobacterial growth or microcystin concentration. Among all parameters, the cyanobacteria growth was negatively correlated with humidity and manganese and positively correlated with atmospheric temperature. No significant correlation was found between microcystin concentration and the climatic parameters. Polymer(chitosan)-enhanced microfiltration (PEMF) and ultrafiltration (PEUF) were further tested as an alternative microcystin removal approach from dense cyanobacteria-rich flows. The dominant cyanobacteria in the water intake, Planktothrix rubescens, was isolated and enriched to simulate cyanobacterial blooms in the lake. The PEMF and PEUF were separately applied to enriched P. rubescens culture (PC) (microcystin = 1.236 µg/L) as well as to the sand filter backwash water (SFBW) of the DWTP where microcystin concentration was higher than 12 µg/L. The overall microcystin removal rates from the final effluent of PC (always <0.15 µg/L) were between 90.1-94.7% and 89.5-95.4% using 4 and 20 mg chitosan/L, respectively. Meanwhile, after the PEMF and PEUF of SFBW, the final effluent contained only 0.099 and 0.057 µg microcystin/L with an overall removal >99%. The presented results are the first from the application of chitosan to remove P. rubescens as well as the implementation of PEMF and PEUF on SFBW to remove cyanobacterial cells and associated toxins.

Long-term trajectory of acquired demyelinating syndrome and multiple sclerosis in children.

AIM: We assessed the frequency, characteristics, and future trajectory of monophasic acquired demyelinating syndromes (ADS) associated with conversion to paediatric multiple sclerosis. METHOD: This was a retrospective observational study of Sardinian children (<18y of age) with onset of ADS between 2001 and 2018. RESULTS: We identified 44 children with ADS (21 males, 23 females; median age at onset 16y, range 4mo-18y), 21 of whom were already presenting with criteria for paediatric multiple sclerosis. The mean crude prevalence of ADS in Sardinian children was 59.2 per 100 000, while incidence was 3.1 per 100 000 per year (1.3 in children aged ≤10y and 11.9 in those aged 10-17y). After a mean (SD) follow-up of 8 years 5 months (5y 4mo), the most common (n=32) trajectory was conversion to paediatric multiple sclerosis. At onset, the total prevalence and mean annual incidence of paediatric multiple sclerosis were 35.6 per 100 000 and 2.3 per 100 000 respectively (0.5 in individuals aged ≤10y, 10.0 in the older group). INTERPRETATION: Sardinia is a very high risk area for ADS in children. Nearly half of this population can already be diagnosed with paediatric multiple sclerosis at onset. Overall, 72% of those with ADS will have paediatric multiple sclerosis after a mean of 8 years. What this paper adds Sardinia is a very high risk area for paediatric acquired demyelinating syndromes (ADS). A high proportion of those with paediatric multiple sclerosis are diagnosed at onset of ADS. After an average 8 years from onset of paediatric ADS, three-quarters of patients are diagnosed with paediatric multiple sclerosis.

Microplastics in real wastewater treatment schemes: Comparative assessment and relevant inhibition effects on anaerobic processes.

The occurrence, fate and removal of microplastics (MPs) in a wastewater treatment plant (WWTP) in Central Italy were investigated together with their potential adverse effects on anaerobic processes. In the influent of the WWTP, 3.6 MPs.L-1 were detected that mostly comprised polyester fibers and particles in the shape of films, ranging 0.1-0.5 mm and made of polyethylene and polypropylene (PP). The full-scale conventional activated sludge scheme removed 86% of MPs, with the main reduction in the primary and secondary settling. MPs particles bigger than 1 mm were not detected in the final effluent and some loss of polymers types were observed. In comparison, the pilot-scale upflow granular anaerobic sludge blanket (UASB) + anaerobic membrane bioreactor (AnMBR) configuration achieved 94% MPs removal with the abatement of 87% of fibers and 100% of particles. The results highlighted an accumulation phenomenon of MPs in the sludge and suggested the need to further investigate the effects of MPs on anaerobic processes. Accordingly, PP-MPs at concentrations from 5 PP-MPs.gTS-1 to 50 PP-MPs.gTS-1 were spiked in the pilot-scale UASB reactor that was fed with real municipal wastewater, where up to 58% decrease in methanogenic activity was observed at the exposure of 50 PP-MPs.gTS-1. To the best of our knowledge, the presented results are the first to report of PP-MPs inhibition on anaerobic processes.

Catchment-wide validated assessment of combined sewer overflows (CSOs) in a mediterranean coastal area and possible disinfection methods to mitigate microbial contamination.

The first phase of this study aimed to evaluate the environmental impact of combined sewer overflow (CSO) events originated from 35 spillways on the Rio Vallescura catchment (Central Italy) and to understand their contribution to the deterioration of the coastal bathing water quality. A specific analytical campaign was carried out in the sewer system and a dynamic rainfall-runoff simulation model was developed and integrated with a water quality model and further validated. The simulations led to identify the most critical spills in terms of flow rate and selected pollutant loads (i.e. suspended solids, biochemical oxygen demand, chemical oxygen demand, total Kjeldahl nitrogen, Escherichia coli). Specifically, the E. coli release in the water body due to CSO events represented almost 100% of the different pollutant sources considered. In the second phase, the applicability of various disinfection methods was investigated on the CSOs introduced into the catchment. On site physical (UV) and lab-scale chemical (peracetic acid (PAA), performic acid (PFA), ozone) disinfectant agents were tested on microbial indicators including E. coli and intestinal enterococci. PFA and ozone were more effective on the removal of both bacteria (above 3.5 log units) even at low concentration and with short contact time; whereas, PAA showed a moderate removal efficiency (around 2.5 log units) only for E. coli. The highest removal efficiency was achieved in the on-site UV unit and none of the indicator bacteria was detected in the final effluent after the sand filtration and UV treatment. Finally, potential scenarios were developed in comparison to the baseline scenario for the management and treatment of CSOs where a mitigation of E. coli loads from 28% to 73% was achieved on the receiving water body, and a comparative cost assessment of the disinfection methods was provided for in situ treatment of the most critical spillway.

Sieving of municipal wastewater and recovery of bio-based volatile fatty acids at pilot scale.

This study combined at pilot scale the recovery of cellulosic primary sludge from the sieving of municipal wastewater followed by the production of bio-based VFAs through acidogenic fermentation. The sieving of municipal wastewater was accomplished by a rotating belt filter which allowed the removal of around 50% of suspended solids when operated at solids loading rates higher than 30-35 kgTSS/m2 h. The solids recovered by sieving contained around 40% of cellulose, which is a suitable raw material for the production of bio-based VFAs. Initially, fermentation batch tests of cellulosic primary sludge were carried out adjusting the initial pH of the sludge at values of 8, 9, 10 and 11, in order to evaluate the best production yields of bio-based VFAs and their composition. The highest VFAs yield achieved was 521 mgCODVFA/gVS occurring when pH was adjusted at 9, while propionic acid reached 51% of the total VFAs. Then, the optimal conditions were applied at long term in a sequencing batch fermentation reactor where the highest potential productivity of bio-based VFAs (2.57 kg COD/m3 d) was obtained by adjusting the pH feeding at 9 and operating with an hydraulic retention time of 6 days under mesophilic conditions. The cost-benefit analyses for the implementation of cellulosic primary sludge recovery was carried out consideringthe anaerobic digestion as reference scenario. The economical assessment showed that the production of bio-based VFAs from cellulosic primary sludge as carbon source and/or as chemical precursors give higher net benefits instead of the only biogas production.

Pilot scale cellulose recovery from sewage sludge and reuse in building and construction material.

The recovery of cellulose in toilet paper from municipal wastewater is one of the most innovative actions in the circular economy context. In fact, fibres could address possible new uses in the building sector as reinforcing components in binder-based materials. In this paper, rotating belt filters were tested to enhance the recovery of sludge rich in cellulose fibres for possible valorisation in construction applications. Recovered cellulosic material reached value up to 26.6 gm-3 with maximum solids removal of 74%. Content of cellulose, hemicellulose and lignin was found averagely equal to 87% of the total composition. Predictive equation of cellulosic material was further obtained. The addition of recovered cellulose fibres in mortars bring benefits in terms of lightness, microstructure and moisture buffering value (0.17 g/m2%UR). Concerning mechanical properties, flexural strength was improved with the addition of 20% of recovered cellulose fibres. In addition, a simplified economic assessment was reported for two possible pre-mixed blends with 5% and 20% of recovered fibres content.

VARS2-linked mitochondrial encephalopathy: two case reports enlarging the clinical phenotype.

BACKGROUND: Mitochondrial respiratory chain consists of five complexes encoded by nuclear and mitochondrial genomes. Mitochondrial aminoacyl-tRNA synthetases are key enzymes in the synthesis of such complexes. Bi-allelic variants of VARS2, a nuclear gene encoding for valyl-tRNA (Val-tRNA) synthetase, are associated to several forms of mitochondrial encephalopathies or cardiomyoencephalopathies. Among these, the rare homozygous c.1100C > T (p.Thr367Ile) mutation variably presents with progressive developmental delay, axial hypotonia, limbs spasticity, drug-resistant epilepsy leading, in some cases, to premature death. Yet only six cases, of which three are siblings, harbouring this homozygous mutation have been described worldwide. CASE PRESENTATION: Hereby, we report two additional cases of two non-related young girls from Sardinia, born from non-consanguineous and healthy parents, carrying the aforesaid homozygous VARS2 variant. At onset both the patients presented with worsening psychomotor delay, muscle hypotonia and brisk tendon reflexes. Standard genetic tests were normal, as well as metabolic investigations. Brain MRI showed unspecific progressive abnormalities, such as corpus callosum hypoplasia (patient A) and cerebellar atrophy (patient A and B). Diagnosis was reached by adopting massive parallel next generation sequencing. Notably clinical phenotype of the first patient appears to be milder compared to previous known cases. The second patient eventually developed refractory epilepsy and currently presents with severe global impairment. Because no specific treatment is available as yet, both patients are treated with supporting antioxidant compounds along with symptomatic therapies. CONCLUSIONS: Given the paucity of clinical data about this very rare mitochondrial encephalopathy, our report might contribute to broaden the phenotypic spectrum of the disorder. Moreover, noteworthy, three out of five pedigrees so far described belong to the Northern Sardinia ethnicity.

Biorefinery of cellulosic primary sludge towards targeted Short Chain Fatty Acids, phosphorus and methane recovery.

Cellulose from used toilet paper is a major untapped resource embedded in municipal wastewater which recovery and valorization to valuable products can be optimized. Cellulosic primary sludge (CPS) can be separated by upstream dynamic sieving and anaerobically digested to recover methane as much as 4.02 m3/capita·year. On the other hand, optimal acidogenic fermenting conditions of CPS allows the production of targeted short-chain fatty acids (SCFAs) as much as 2.92 kg COD/capita·year. Here propionate content can be more than 30% and can optimize the enhanced biological phosphorus removal (EBPR) processes or the higher valuable co-polymer of polyhydroxyalkanoates (PHAs). In this work, first a full set of batch assays were used at three different temperatures (37, 55 and 70 °C) and three different initial pH (8, 9 and 10) to identify the best conditions for optimizing both the total SCFAs and propionate content from CPS fermentation. Then, the optimal conditions were applied in long term to a Sequencing Batch Fermentation Reactor where the highest propionate production (100-120 mg COD/g TVSfed·d) was obtained at 37 °C and adjusting the feeding pH at 8. This was attributed to the higher hydrolysis efficiency of the cellulosic materials (up to 44%), which increased the selective growth of Propionibacterium acidopropionici in the fermentation broth up to 34%. At the same time, around 88% of the phosphorus released during the acidogenic fermentation was recovered as much as 0.15 kg of struvite per capita·year. Finally, the potential market value was preliminary estimated for the recovered materials that can triple over the conventional scenario of biogas recovery in existing municipal wastewater treatment plants.

Influence of aeration cycles on mechanical characteristics of elastomeric diffusers in biological intermittent processes: Accelerated tests in real environment.

The paper deals with the evaluation of the effect of on/off switching of diffuser membranes, in the intermittent aeration process of the urban wastewater treatments. Accelerated tests were done using two types of commercial EPDM diffusers, which were submitted to several consecutive cycles up to the simulation of more than 8 years of real working conditions. The effect of this switching on the mechanical characteristics of the membranes was evaluated in terms of pressure increment of the air operating at different flow rates (2, 3.5 and 6 m3/h/diff): during accelerated tests, such increment ranged from 2% to 18%. The intermittent phases emphasized the loss both of the original mechanical proprieties of the diffusers and of the initial pore shapes. The main cause of pressure increment was attributed to the fouling of the internal channels of the pores. Further analyses performed by scanning electron microscopy and by mechanical tests on EPDM membrane, using a traditional tensile test and a non destructive optical method, from which the Young's Modulus was obtained, supported previous conclusions. Any changes in terms of oxygen transfer parameters (KLa and SOTE%) were specifically founded by causing to the repeated on/off switching.

Osmosis process for leachate treatment in industrial platform: Economic and performances evaluations to zero liquid discharge.

The industrial processes require large quantities of water. The presence of discharges results not only in significant environmental impact but implies wastage of water resources. This problem could be solved treating and reusing the produced wastewaters and applying the new zero liquid discharge approach. This paper discusses the design and the performances of reverse osmosis membranes for the upgrading of full scale platform for industrial liquid wastes. The final effluent from the ultrafiltration unit of the full scale plant was monitored to design the reverse osmosis unit. Previous modelling phase was used to evaluate the specific ordinary and maintenance costs and the final effluent quality (2.7 €/m3). The system was designed in triple stages at different operative pressures. The economic feasibility and the payback period of the technology at different percentages of produced permeate were determined. The recovery of 90% was identified as profitable for the reverse osmosis application. One experimental pilot plant applying the reverse osmosis was used to test the final effluent. Moreover, the same flow was treated with second pilot system based on the forward osmosis process. The final efficiencies were compared. Removals higher than 95% using the reverse system were obtained for the main macropollutants and ions. No sustainable applicability of the forward osmosis was determined.

Dinitrogen oxide (N2O) emission in the treatment of urban wastewater via nitrite: influence of liquid kinetic rates.

N2O emission was studied in a continuous process via nitrite for real urban wastewater treatment. The relationship between the gaseous forms and the liquid kinetic rates of nitritation and denitritation was investigated. N2O mass load and global nitrogen mass balance were quantified. The emission factor of the N2O (gN2Oemitted/kg mixed liquor volatile suspended solids [MLVSS]/d) was calculated. Incrementing the nitritation rate permits the reduction of N2O emission by 78%. Instead, an N2O decrease of 93% was observed by increasing the denitritation velocity. The determinant role of the anoxic phase in the production of dinitrogen oxide was identified. The contribution of N2O emission from the anoxic phase (4.8 gN2O-N/kgMLVSS/d) was enhanced under limiting denitritation conditions (kd lower than 0.08 kgNOx-N/kgMLVSS/d). N2O production increased by five times with the accumulation of nitrites in the solution up to 200 mg/L. Strict correlation between free ammonia concentration and nitritation rate was found as a possible signal of further ammonia oxidizing bacteria selection.