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It is still one of the significant solutions to treat saline wastewater with thermal desalination technology, especially falling film evaporators. To improve the performance of the falling film evaporator, a numerical study on the gas–liquid two-phase flow characteristics of saline wastewater in the vertical pipe was conducted using the VOF model. The results showed that the inlet velocity of the saline wastewater increased under the same operating conditions, resulting in the thickening of the liquid film and the increase of the average convective heat transfer coefficient. Increasing the inlet temperature of the working liquid reduced the temperature difference, which led to a decrease of the average convective heat transfer coefficient. In addition, as the inlet concentration of the working liquid increased, the film flow rate and the average convective heat transfer coefficient first decreased and then increased slightly. The experimental results verified the accuracy of the numerical simulation, and the average error was 9.27%. HIGHLIGHTS The study of fluid microflow combined with heat transfer was proposed.; The distribution of heat transfer coefficient based on numerical simulation.; The distribution of heat transfer coefficient is correctly verified by experiments.; The effects of the various operating parameters on the heat and mass transfer processes are studied.

Halophiles are key microorganisms to potentially overcome the salinity-induced limitation in anaerobic bioremediation of organic pollutants and energy recovery when using conventional inoculums. This study aimed to enrich halophiles from hypersaline sediment and optimize their use as alternative inoculum for fermentative hydrogen production. Batch assays of 15 combinations (i.e., pH 6–10, salinity of 10–70 g-NaCl/L, and iron concentration of 0.2–1.0 g-FeSO4/L) were conducted using glucose as a substrate. To potentially boost the efficiency via optimization of operational conditions, response surface methodology (RSM) was employed. The maximum obtained hydrogen yield (HY) of 151 mL/g-COD (1.29 mol-H2/mol-glucose) was achieved at pH 6.0, 40 g-NaCL/L, and 0.6 g-FeSO4/L. The results further emphasize the negative impacts of salinity 8, along with the beneficial role of iron supplementation (0.3–1.0 g-FeSO4/L). By using and validating a multivariate optimization model using desirability function, towards maximum HY, the predicted value was 155 mL/g-COD at pH 6.65, 70 g-NaCl/L, and 0.2 g-FeSO4/L. The microbial community analysis revealed that the enrichment of raw sediment enhanced the biodiversity, and then showed that Halobacteroidaceae bacteria were the key players in producing H2 from glucose. Overall, with respect to the achieved competitive HY (1.29 mol/mol-glucose), the use of halophiles-based inoculum is feasible to overcome the limitations of DF when treating saline wastewater, and future studies/implications with real effluents are worthy.

The present study focuses on determining the phyto-treatment efficiency for treatment of moderately saline wastewater using organic raw materials, such as rice husk, coconut husk, rice straw, and charcoal. The moderately saline wastewater with total dissolved solids (TDS) concentration up to 6143.33 ± 5.77 mg/L was applied to the lysimeters at the rate of 200 m3 ha–1 day–1 in five different lysimeter treatments planted with Eucalyptus camaldulensis (T1, T2, T3, T4, and T5). T1 was a control without any filter bedding material, whereas rice straw, rice husk, coconut husk, and charcoal were used as filter bedding materials in the T2, T3, T4, and T5 treatment systems, respectively. Each treatment showed significant treatment efficiency wherein T3 had the highest removal efficiency of 76.21% followed by T4 (67.57%), T5 (65.18%), T2 (46.46%), and T1 (45.5%). T3 and T4 also showed higher salt accumulation, such as sodium (Na) and potassium (K). Further, the pollution load in terms of TDS and chemical and biological oxygen demand significantly reduced from leachate in the T3 and T4 treatments in comparison with other treatments. Parameters of the soil, such as electrical conductivity, exchangeable sodium percentage, and cation exchange capacity did not show values corresponding to high salinity or sodic soils, and therefore, no adverse impact on soil was observed in the present study. Also, Eucalyptus camaldulensis plant species showed good response to wastewater treatment in terms of growth parameters, such as root/shoot weight and nitrogen, phosphorus, and potassium (NPK) uptake, plant height, biomass, and chlorophyll content. Root and shoot dry weight were in the order T3 (51.2 and 44.6 g)>T4 (49.3 and 43.5 g) > T5 (47.6 and 40.5 g) > T2 (46.9 and 38.2 g) > T1 (45.6 and 37.1 g). Likewise, the total chlorophyll content was highest in T3 (12.6 μg/g) followed by T4 (12.3 μg/g), T5 (11.9 μg/g), T2 (11.5 μg/g), and the control, that is, T1 (11.0 μg/g). However, the most promising results were obtained for T3 and T4 treatments in comparison with the control (T1), which implies that, among all organic raw materials, coconut and rice husks showed the highest potential for salt accumulation and thereby wastewater treatment. Conclusively, the findings of the study suggest that organic raw material–based amendments are useful in managing the high salts levels in both plants and leachates.

This study investigated the treatment of a shipboard slop containing commercial gasoline in a pilot plant scale consisting of a membrane biological reactor (MBR) and photocatalytic reactor (PCR) acting in series. The MBR contributed for approximately 70% to the overall slop purification. More precisely, the biological process was able to remove approximately 40%, on average, of the organic pollution in the slop. Nevertheless, the membrane was capable to retain a large amount of organic molecules within the system, amounting for a further 30% of the influent total organic content removal. However, this affected the membrane fouling, thus resulting in the increase of the pore blocking mechanism that accounted for approximately 20% to the total resistance to filtration (2.85∙10 13 m −1 ), even if a significant restoration of the original membrane permeability was obtained after chemical cleanings. On the other hand, the biological treatment produced a clear solution for the photocatalytic system, thereby optimizing the light penetration and generation of highly oxidizing active oxygen species that enabled the degradation of bio-recalcitrant compounds. Indeed, low total organic carbon (TOC) values (

Background: Microalgal biotechnology has gained much attention previously. Monoculture algae cultivation has been carried out extensively in the last decades. However, although the mixed microalgae cultivation has some advantageous over pure cultures, there is still a lack of knowledge about the performance of mixed cultures. Objective: In this study, it has been tried to investigate all growth aspects of marine and freshwater microalgal species in a mixed culture and their biological effects on biomass growth and composition based on wastewater nutrient consumption. Material and Methods: Three algal species of Chlorella vulgaris, Scenedesmus obliquus, and Nannochloropsis sp. were cultivated in saline wastewater individually, then the effects of mixing the three strains on biomass productivity, nutrient removal efficiency, chlorophyll, carotenoid, and lipid content were investigated. Results: The obtained results revealed that the mixed culture of three strains showed the highest biomass productivity of 191 mg. L-1.d-1. Also, while there were no significant differences between the performance of mono and mixed culture of algal species in the removal efficiency of wastewater nutrients, the three-strain microalgal mixed culture showed the highest values of 3.5 mg.L-1.d-1 and 5.75 mg.L-1.d-1 in the removal rate of phosphate and nitrate, respectively. In terms of total chlorophyll and carotenoid per produced biomass, however, the mixed culture of three species showed the lowest values of 4.08 and 0.6 mg. g biomass-1, respectively. Conclusions: The finding proves the potential of attractive and economically feasible mixed microalgae cultivation for high percentage nutrient removal and microalgal biomass production.

Sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), as two anionic surfactants, have diffused into environments such as surface water and ground water due to extensive and improper use. The effects on the removal performance and microbial community of sequencing batch reactors (SBRs) need to be investigated in the treatment of saline wastewater containing 20 g/L NaCl. The presence of SDS and SDBS could decrease the removal efficiencies of ammonia nitrogen and total phosphorus, and the effect of SDS was more significant. The effect of surfactants on the removal mainly occurred during the aeration phase. Adding SDS and SDBS can reduce the content of extracellular polymeric substances (EPS). In addition, SDS and SDBS also can reduce the inhibition of high salinity on sludge activity. A total of 16 s of rRNA sequencing analysis showed that the addition of surfactants reduced the diversity of microbial communities; besides, the relative abundance value of the dominant population Proteobacteria increased from 91.66% to 97.12% and 93.48% when SDS and SDBS were added into the system, respectively.

An aerobic granular sludge (AGS) sequencing batch reactor (SBR) adapted to salinity (12gL-1 NaCl) was operated under alternating anaerobic-aerobic conditions for the treatment of synthetic saline wastewater containing endocrine-disrupting chemicals (EDCs), namely 17estradiol (E2), 17ethinylestradiol (EE2) and bisphenol-A (BPA). The SBR was intermittently fed with the EDCs at 2mgL-1 of each compound. E2 was completely biodegraded, with 60% to 80% removal attained anaerobically and the remaining quickly consumed under aeration. EE2 was sorbed onto the granular sludge biomass in the anaerobic period, but it was desorbed in subsequent cycles even when the compound was not supplied to the reactor. BPA removal was poor but improved after bioaugmentation with an EDCs degrading bacteria. EDCs shock loads did not significantly affect the COD removal nor the activity of ammonium- and nitrite-oxidizing bacteria (AOB and NOB, respectively). In contrast, the activity of phosphate-accumulating organisms (PAOs) was affected, implying a decrease in P removal within the aerobic phase. AGS core microbiome grouped most bacteria belonging to the phylum Proteobacteria, followed by Bacteroidetes. The microbial profile showed that the introduction of the EDCs mixture increased the relative abundance of Chryseobacterium and Flavobacterium. AOB and NOB species were detected in the AGS biomass, with the latter showing lower relative abundance. Different PAOs, such as Rhodocyclus, Tetrasphaera and Gemmatimonas, were also part of the microbial community, but the addition of EDCs decreased significantly the relative abundance of Rhodocyclus. High microbial diversity was sustained over reactor operation, with the main bacterial groups responsible for nutrients and EDCs removal preserved in the AGS system. The results pointed to the maintenance of a core microbiome over reactor operation that may be related to the stability of the AGS process during EDCs loading., This study was supported in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/Brasil) – Finance Code 001 and the other part was financed by National Funds from Fundação para a Ciência e a Tecnologia (FCT/Portugal) - through the project AGeNT - PTDC/BTA-BTA/31264/2017 (POCI-01-0145-FEDER 031264)and the project CBQF - UID/Multi/50016/2019, info:eu-repo/semantics/publishedVersion

Effective biological treatment of high salt content wastewater requires consideration of both salt and organic toxicity. This study treated a synthetic saline wastewater containing NaCl (100gL-1) and 2,4-dimethylphenol (1.2gL-1) with a hybrid system consisting of a biological reactor containing spiral-coiled polymeric tubing through which the mixed feed was pumped. The tubing wall was permeable to the organic contaminant, but not to the salt, which allowed transfer of the organic into the cell-containing bioreactor contents for degradation, while not exposing the cells to high salt concentrations. Different grades of DuPont Hytrel polymer were examined on the basis of organic affinity predictions and experimental partition and mass transfer tests. Hytrel G3548 tubing showed the highest permeability for 2,4-dimethylphenol while exerting an effective salt barrier, and was used to verify the feasibility of the proposed system. Very high organic removal (99% after just 5h of treatment) and effective biodegradation of the organic fraction of the wastewater (>90% at the end of the test) were observed. Complete salt separation from the microbial culture was also achieved.

Significant rise in concentration of saline wastewater entering the treatment plants has been resulting in many problems in the biological treatment processes. On the other hand, the specific conditions of physicochemical treatment methods for saline and hyper saline wastewater have limited their application on a large-scale. Over the past few decades, Sequencing Batch Reactor (SBR) process has been widely used as an efficient, well-designed and practical approach for treatment of domestic and industrial wastewater due to its cost-effectiveness and simplicity. SBR Performance can enhance by providing simultaneous suspended and attached growth of microorganisms which act as a hybrid growth. In this study, a lab-scale Hybrid Sequencing Batch Reactor (HSBR) with 6.4 l working volume was used to examine the effect of salinity (NaCl), increased from 0 to 6.7% (g NaCl/ L wastewater), on the biological treatment. Therefore, COD, MLSS, MLVSS and SVI parameters have been measured over a period of 7 months of operation. The operational parameters namely pH, dissolved oxygen (DO) and temperature were 7.5–8.5, 1.5–6.8 mg /L and 20–25 °C respectively during whole experiment. Influent COD of synthetic wastewater was maintained at 650 ± 25 mg/L. The HSBR Cycle time including, influent feeding, React, Settling and effluent discharge were 1/20/1/1 h respectively. Results indicated that by increasing salt concentration from 0 to 67.7 g NaCl/L, the COD removal efficiency reduced from 94.22 to 53.69%. Moreover, as the NaCl concentration increased, MLSS rose up to 69%, while MLVSS almost stayed constant and SVI dropped by 83%. The results indicated that the simultaneous use of suspended and attached growth of microorganisms and gradual increasing of salt content of wastewater could lead to greater biomass concentration and ultimately improvement in the degradation of organic matter. Besides, settling performance and its velocity were noticeably improved by increasing salinity.

Sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), as two anionic surfactants, have diffused into environments such as surface water and ground water due to extensive and improper use. The effects on the removal performance and microbial community of sequencing batch reactors (SBRs) need to be investigated in the treatment of saline wastewater containing 20 g/L NaCl. The presence of SDS and SDBS could decrease the removal efficiencies of ammonia nitrogen and total phosphorus, and the effect of SDS was more significant. The effect of surfactants on the removal mainly occurred during the aeration phase. Adding SDS and SDBS can reduce the content of extracellular polymeric substances (EPS). In addition, SDS and SDBS also can reduce the inhibition of high salinity on sludge activity. A total of 16 s of rRNA sequencing analysis showed that the addition of surfactants reduced the diversity of microbial communities; besides, the relative abundance value of the dominant population Proteobacteria increased from 91.66% to 97.12% and 93.48% when SDS and SDBS were added into the system, respectively.

Biological nutrient removal performances and kinetics of autochthonous marine biomass in forms of activated sludge and aerobic granular sludge were investigated under different salinity and sludge retention time (SRT). Both the biomasses, cultivated from a fish-canning wastewater, were subjected to stepwise increases in salinity (+2 gNaCl L−1), from 30 gNaCl L−1 up to 50 gNaCl L−1 with the aim to evaluate the maximum potential in withstanding salinity by the autochthonous marine biomass. Microbial marine species belonging to the genus of Cryomorphaceae and of Rhodobacteraceae were found dominant in both the systems at the maximum salinity tested (50 gNaCl L−1). The organic carbon was removed with a yield of approximately 98%, irrespective of the salinity. Similarly, nitrogen removal occurred via nitritation-denitritation and was not affected by salinity. The ammonium utilization rate and the nitrite utilization rate were approximately of 3.60 mgNH4-N gVSS−1h−1 and 10.0 mgNO2-N gVSS−1h−1, respectively, indicating a high activity of nitrifying and denitrifying bacteria. The granulation process did not provide significant improvements in the nutrients removal process likely due to the stepwise salinity increase strategy. Biomass activity and performances resulted affected by long SRT (27 days) due to salt accumulation within the activated sludge flocs and granules. In contrast, a lower SRT (14 days) favoured the discharge of the granules and flocs with higher inert content, thereby enhancing the biomass renewing. The obtained results demonstrated that the use of autochthonous-halophilic bacteria represents a valuable solution for the treatment of high-strength carbon and nitrogen saline wastewater in a wide range of salinity. Besides, the stepwise increase in salinity and the operation at low SRT enabled high metabolic activity and to avoid excessive accumulation of salt within the biomass aggregates, limiting their physical destructuration due to the increase in loosely-bound exopolymers.

Saline wastewater is known to affect the performance of phosphate-accumulating organisms (PAOs) in enhanced biological phosphorus removal (EBPR) process. However, studies comparing the effect of salinity on different PAO clades are lacking. In this study, ‘Candidatus Accumulibacter phosphatis’ Clade I and II (hereafter referred to as PAOI and PAOII) were highly enriched (∼90% in relative abundance as determined by quantitative FISH) in the form of granules in two sequencing batch reactors. Anaerobic and aerobic batch experiments were conducted to evaluate the effect of salinity on the kinetics and stoichiometry of PAOI and PAOII. PAOI and PAOII communities showed different priority in using polyphosphate (poly-P) and glycogen to generate ATP in the anaerobic phase when exposed to salt, with PAOI depending more on intracellular poly-P degradation (e.g., the proportion of calculated ATP derived from poly-P increased by 5–6% at 0.256 mol/L NaCl or KCl) while PAOII on glycolysis of intracellularly stored glycogen (e.g., the proportion of calculated ATP derived from glycogen increased by 29–30% at 0.256 mol/L NaCl or KCl). In the aerobic phase, the loss of phosphate uptake capability was more pronounced in PAOII due to the higher energy cost to synthesize their larger glycogen pool compared to PAOI. For both PAOI and PAOII, aerobic conversion rates were more sensitive to salt than anaerobic conversion rates. Potassium (K+) and sodium (Na+) ions exhibited different effect regardless of the enriched PAO culture, suggesting that the composition of salt is an important factor to consider when studying the effect of salt on EBPR performance.

Saline municipal wastewater treatment is a challenging environmental issue in coastal cities, due to the discharge of saline water into the sewers. The present research article focuses on the phytoremediation of high saline municipal wastewater by Ruppia maritime, a widespread plant which can be found in saline medium such as traditional fish ponds, estuaries, tidal flats, salt pans, coastal paddy fields, coastal lagoons, marsh pools, and mangrove salt marshes in Khuzestan province, Iran. The experimental data was obtained using a pilot plant constructed in Chobeineh wastewater treatment plant in Ahvaz city, fed by activated sludge effluent in 3 levels of electrical conductivity (EC) (10, 15, 20 ms cm−1), during 45 days of the experiment. Chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and total suspended solids (TSS) were daily monitored in blank and pilot study. The COD removal decreased from 83.26% to 72.39% by increasing the EC level from 10 to 20 ms cm−1, respectively. The experimental data will practically be an appropriate source of information for environmental engineers to design a natural treatment scenario for saline wastewater treatment.

Phenols are chemical compounds which are included in the high priority of pollutants by environmental protection agency (USEPA). The presence of high concentrations of phenols in wastewaters like oil refineries, petrochemical plants, olive oil, pesticide production and oil field operations contain high soluble solids (TDS) and in an olive oil plant, wastewater is acidic, high salty and phenol concentrations are in the range of 0.1- 1%. Kinetic parameters were calculated according to Monod, Modified Stover- Kincannon, Hamoda and Haldane models. The influence of different initial phenol concentrations on the biodegradation rate was performed. The concentrations of phenol varied from 0 to 500 mg/l. The value of Ki in saline phenolic wastewater in attached growth systems was higher than suspended growth systems that represented a higher phenol inhibition in suspended growth systems. It was obvious that the best model fitting the obtained data are Hamoda model and the Modified Stover-Kincannon model, having highest R 2 values of 0.991 and 1, respectively. The value of Ki in saline phenolic wastewater in attached growth system was higher than suspended growth systems which represented a higher phenol inhibition in suspended growth systems. Hamoda model and the Modified Stover-Kincannon model having highest R2 value of 0.991 and 1, respectively, and also predicting reasonable kinetic coefficient values.

This study investigated fundamental mechanisms that anaerobic biomass employ to cope with salinity, and applied these findings to a continuous SAMBR. When anaerobic biomass was exposed to 20 and 40 g NaCl/L for 96 h, the main solute generated de novo by biomass was trehalose. When we separately introduced trehalose, N-acetyl-β-lysine and potassium into a batch culture a slight decrease in sodium inhibition was observed. In contrast, the addition of 0.1 mM and 1 mM of glycine betaine dramatically improved the adaptation of anaerobic biomass to 35 g NaCl/L, and it continued to enhance the adaptation of biomass to the salt for the next three batch feedings without further addition. No shift in archaeal microbial diversity was found when anaerobic biomass was exposed in batch mode to 35 g NaCl/L for 360 h, and no changes were found when glycine betaine was added. The dominant species identified under these conditions were Methanosarcina mazeii and Methanosaeta sp. The addition of 5 mM glycine betaine to a continuous SAMBR at 12 h hydraulic retention time (HRT), and operation in batch mode for 2 days can significantly enhance saline (35 g NaCl/L) synthetic sewage degradation. In addition, the injection of 1 mM of glycine betaine into a SAMBR for five subsequent days also significantly enhanced dissolved organic carbon (DOC) removal from sewage under these conditions. The main compatible solutes generated by anaerobic biomass after 44 days exposure to 35 g NaCl/L in a SAMBR were N-acetyl-β-lysine and glycine betaine. Finally, the addition of 1 mM glycine betaine to the medium was beneficial for anaerobic biomass in batch mode at 20 °C under saline and non saline conditions.

A nitrificação biológica em meio salino foi investigada em sistema contínuo, a partir de um efluente sintético contendo 152,44 mg L-1 de nitrogênio amoniacal total. Os testes com adição de concentrações crescentes de sal (100, 250, 500, 1.000, 2.000, 4.000, 8.000, 10.000 e 15.000 mg Cl- L-1) foram realizados em um biorreator em escala de laboratório de 5,7 L. Neste estudo, o objetivo foi avaliar a resposta da técnica de respirometria na identificação da toxicidade da biomassa nitrificante em diferentes concentrações salinas. Durante o período experimental, o biorreator operou com o tempo de retenção hidráulica de 48h e valores de OD, pH e temperatura foram mantidos em 4,0-5,0 mg L-1, 7,5 e 25°-30°C, respectivamente. Os ensaios de respirometria foram realizados em triplicata, com a utilização da sonda de oxigênio dissolvido. Os resultados da respirometria constataram que ambas as taxas de consumo de oxigênio (OUR) e de consumo especifico de oxigênio (SOUR) aumentaram até a concentração de 1.000 mg Cl- L-1, quando o máximo de eficiência de nitrificação de 65,18% foi obtida com aproximadamente 90 dias de operação do sistema. No entanto, o aumento gradual a partir de 2.000 mg Cl- L-1, resultou na queda dos valores de consumo de oxigênio, ocorrendo consequentemente a redução da atividade metabólica da biomassa, verificada com a redução dos valores de eficiência de nitrificação. Estes resultados evidenciam que a técnica de respirometria apresentou-se como uma ferramenta eficaz e segura para avaliação da toxicidade da biomassa do lodo ativado, sendo capaz de detectar a queda da atividade celular na presença de inibidores, como elevadas concentrações de salinidade. Biological nitrification in a saline medium was investigated in a continuous system of a synthetic effluent containing 152.44 mg L-1 of total ammonia nitrogen. Tests were performed with the addition of increasing concentrations of salt (100, 250, 500, 1,000, 2,000, 4,000, 8,000, 10,000 and 15,000 mg Cl- L-1) in a 5.7 L laboratory bioreactor. The objective of the study was to evaluate respirometry technique responses in order to identify toxicity in nitrifying biomass with varying salt concentrations. During the experiment, the bioreactor was operated with a hydraulic retention time of 48 h, and DO, pH and temperature maintained at 4.0-5.0 mg L-1, 7.5 and 25°-30°C, respectively. The respirometric assays were performed in triplicate, using a dissolved oxygen probe. The results of respirometry found that both oxygen uptake rates (OUR) and specific oxygen consumption (SOUR) increased up to a concentration of 1,000 mg Cl- L-1, when the nitrification efficiency maximum of 65.18% was obtained after approximately 90 days of system operation. However, a gradual increase to 2,000 mg Cl- L-1 resulted in a decrease in oxygen consumption values, reducing the metabolic activity of the biomass, as verified by a reduction in nitrification efficiency values. The results show that the respirometry technique is an effective and reliable tool for assessing the toxicity of activated sludge, and that it is able to detect a decrease in cellular activity in the presence of inhibitors, such as high concentrations of salinity.

Industrial wastewater often has a high salt content, due to specific factories and to the use of seawater in coastal areas. Once it has reached the activated sludge treatment, saline wastewater may cause biomass inhibition and dramatic loss in purification efficiency. In the present work, the inhibiting effect of saline influent was experimentally evaluated through respirometric tests on samples of the incoming wastewater. Activated sludge was grown in bench-scale continuous flow stirred tank reactor (CFSTR), supplied with synthetic wastewater. Synthetic saline wastewater was prepared using sodium chloride and sodium sulphate at different concentrations. Samples of mixed liquor were drawn from the CFSTR reactor and fed with saline wastewater in shock-load or in continuous mode, then respiration activity and carbon removal yield were evaluated. In batch mode (shock-load), salt/biomass ratios between 0.37 and 30.7 gsalt gvss(-1) gave respiration inhibition between 4% and 84% respectively. The respirometry bioassay required a short response time and the values of respiration inhibition predicted the loss in carbon removal efficiency with a good accuracy. In continuous mode, for salt/biomass ratio of 35.5 gsaltgvss(-1), respiration inhibition of 81% was obtained. This work showed that a relation between inhibition in shock-load and inhibition in continuous mode can be determined, therefore, the procedure herein proposed allows performing offline bioassays on real biological plants, to assess in real time the inhibiting effect of the incoming wastewater before it reaches the activated sludge reactor.

In this study, the performance of an aerobic moving bed biofilm reactor (MBBR) was assessed for the removal of phenol as the sole substrate from saline wastewater. The effect of several parameters namely inlet phenol concentration (200-1200 mg/L), hydraulic retention time (8-24 h), inlet salt content (10-70 g/L), phenol shock loading, hydraulic shock loading and salt shock loading on the performance of the 10 L MBBR inoculated with a mixed culture of active biomass gradually acclimated to phenol and salt were evaluated in terms of phenol and chemical oxygen demand (COD) removal efficiencies. The results indicated that phenol and COD removal efficiencies are affected by HRT, phenol and salt concentration in the bioreactor saline feed. The MBBR could remove up to 99% of phenol and COD from the feed saline wastewater at inlet phenol concentrations up to 800 mg/L, HRT of 18 h and inlet salt contents up to 40 g/L. The reactor could also resist strong shock loads. Furthermore, measuring biological quantitative parameters indicated that the biofilm plays a main role in phenol removal. Overall, the results of this investigation revealed that the developed MBBR system with high concentration of the active mixed biomass can play a prominent role in order to treat saline wastewaters containing phenol in industrial applications as a very efficient and flexible technology.

This research effort focused on evaluating the toxicity of the saline waste water generated from washing of Indiana Department of Transportation (INDOT) deicing trucks and to study the feasibility of discharging it into wastewater treatment plants. Performance of activated sludge treating wastewater under varying levels of salt concentration was studied by measuring the Chemical Oxygen Demand (COD), activated sludge oxygen uptake rate (OUR) and Turbidity. For the COD tests, wastewater was tested with salt concentrations ranging from 0 mg/L – 1500 mg/L. Within this range there is no impact of salt on COD stabilization, suggesting that the microorganisms are not adversely impacted by salinity in this range. Turbidity tests were conducted for salt concentrations of 0 - 10,000 mg/L. Below a concentration of 3000 mg/ L salt did not have any significant impact on the turbidity. Concentrations above 3000 mg/L aided in flocculation of particles and resulted in faster settling of colloidal solids and reduction in turbidity. Another component of the study was to examine the fate and chemistry of ferric ferro/ferri cyanide, an anti-caking complex that is added to deicing salt. Although, the complex form of cyanide is harmless, in the presence of sunlight it can dissociate to form free cyanide that is highly toxic. Deicing salts collected from INDOT’s West Lafayette and Lafayette Facilities were tested for total and amenable cyanide levels. Lafayette road salt had high levels of cyanide that could lead to violation of pretreatment standards on cyanide, if this salt wash water is discharged to wastewater treatment plant. Respirometry was used for the impact assessment of variable salt concentrations on the biological performance of a low strength activated sludge samples for a POTW using a static liquid – gas flow (GFS) respirometer with salt concentrations varying from 0 – 10% . Generally, positive effect in oxygen uptake rate (OUR) was noticed on low salt concentrations up to 2% and a sharp decrease thereafter. A salt concentration of 6% resulted in a 50% decrease in respiration rate of the tested activated sludge. Further studies should involve the effect of saline shock loads in the specific ammonia uptake rate (SAUR) and specific nitrate uptake rate (SNUR) in addition to the final effluent quality.

An Aerated Submerged Biological Filter was used to promote biological nitrification of a synthetic saline wastewater. Black PVC corrugated plates were used to make the structured packing of the 6 liter reactor. Nitrate, nitrite, and ammonia concentrations, pH and DO were periodically measured, according to APHA (1985). In spite of the deleterious effect of salinity, it was possible to obtain nitrogen removal efficiencies as high as 95% for a 25 g/L salt concentration after a three-day reaction in the batch reactor. Continuous operation using a NaCl concentration of 25 g/L was tested using three different hydraulic retention times: 7, 15, and 25 hours. An increase in ammonia removal was observed when the retention time was increased from 7 to 15 hours. However, no further notable increase was obtained for a 25 hour retention time, showing that nitrogen removal tends towards a maximum limit of about 80%.

Background: High concentration of salt makes biological treatment impossible due to bacterial plasmolysis. The present research studies the process of electrochemical oxidation efficiency and optimal levels as important factors affecting pH, salt concentration, reaction time and applied voltage. Methods: The sample included graphite electrodes with specifications of 2.5 cm diameter and 15 cm height using a reactor with an optimum capacity of 1 L. Sixty samples were obtained with the aid of the experiments carried out in triplicates for each factor at 5 different levels. The entire experiments were performed based on standard methods for water and waste water treatments. Results: Analysis of variance carried out on effect of pH, salt concentration, reaction time and flow intensity in elimination of chemical oxygen demand (COD) showed that they are significant factors affecting this process and reduce COD with a coefficient interval of 95% and test power of 80%. Scheffe test showed that at optimal level, a reaction time of 1 hour, 10 g/L concentration, pH = 9 and 15 V electrical potential difference were obtained. Conclusion: Waste waters containing salt may contribute to the electro-oxidation process due to its cations and anions. Therefore, the process of electrochemical oxidation with graphite electrodes could be a proper strategy for the treatment of saline wastewater where biological treatment is not possible.