Percentage Removal Efficiency Research Articles

Promoting Effect of H+ and Other Factors on NO Removal by Using Acidic NaClO2 Solution

In this study, NaClO2 was selected as a denitration oxidant. In order to clarify the mechanism of NaClO2 as an oxidation agent for NO removal efficiency, the effects of H+ and other factors (NaClO2 concentration, temperature, and the other gas) on the NO removal efficiency were investigated. NaClO2 showed a promotional ability on NO removal, whose efficiency increased with the increase of NaClO2 concentration. One hundred percent removal efficiency of NO could be achieved when the NaClO2 concentration was 0.014 mol/L. Furthermore, raising the reaction temperature benefited the removal of NO. The lower the pH, the better the NO removal efficiency. The promoting effect of H+ on the NO removal was studied by the Nernst equation, ionic polarization, and the generation of ClO2. Under the optimal conditions, the best removal efficiency of NO was 100%. Based on the experimental results, the reaction mechanism was finally speculated.

Water reuse nexus with resource recovery: On the fluidized-bed homogeneous crystallization of copper and phosphate from semiconductor wastewater

Abstract Green and sustainable strategies aim for the development of manufacturing processes that maximize the use of resources instigating semiconductor industry to adopt zero-liquid discharge policies. Complexity and variations of semiconductor wastewater effluents opens an opportunity for resource recovery (i.e. copper from chemical-mechanical polishing) including heavy metals and inorganic ions (i.e. phosphate from acid cleaning). This present work demonstrates the capabilities of fluidized-bed homogeneous crystallization as treatment technology to process water effluents for industrial reuse while simultaneously recovering precious resources such as copper and phosphate. Operational variables have been optimized considering the combination of both effluents to produce high quality copper phosphate granules. The optimum copper percentage removal and crystallization efficiency were 99% and 96.07% respectively obtained at pHe 6.0–6.5, 1.25 [PO4−3]in/[Cu2+]in at hydraulic retention time 22.5 min with 0.51 kg Cu2+/m2 h and fixed [Cu2+]in loading of 4.5 mM. The recovered crystals have an average particle diameter of ∼1 mm and were characterized identifying libethenite (Cu2PO4OH) as main recovered products.

Characterization of Aspergillus niger siderophore that mediates bioleaching of rare earth elements from phosphorites.

Siderophores are extra-cellular inducible compounds produced by aerobic microorganisms and plants to overcome iron insolubility via its chelation and then uptake inside the cell. This work aims to study the characteristics of siderophore that is produced by a rhizosphere-inhabiting fungus. This fungus has been morphologically and molecularly identified as Aspergillus niger with the ability to produce 87% siderophore units. The obtained siderophore in PDB medium gave a positive result with tetrazolium test and a characteristic spectrum with a maximum absorbance at 450nm in FeCl3 test that did not shift in response to different pH degrees (5-9). This indicates that the obtained siderophore is a trihydroxymate in nature. After purification, the FTIR and NMR analyses showed that the obtained siderophore is considered to be ferrichrome. The purified siderophore has been further evaluated as a tool to extract uranium, thorium and rare earth elements (REEs) from Egyptian phosphorites obtained from Abu Tartur Mine area. The inductively coupled plasma atomic emission spectroscopy analysis showed that the highest removal efficiency percentage was for uranium (69.5%), followed by samarium (66.7%), thorium (55%), lanthanum (51%), and cerium (50.1%). This result confirmed the ability of hydroxymate siderophores to chelate the aforementioned precious elements, a result that paves the way for bioleaching to replace abiotic techniques in order to save the cost of such elements in an environmentally friendly way.

Concentration and reduction of antibiotic residues in selected wastewater treatment plants and receiving waterbodies in Durban, South Africa

In the province of KwaZulu-Natal, South Africa the incidence of resistant tuberculosis, upper respiratory tract diseases as well as diarrhoeal and parasitic infections is high. Treatment of these diseases with antibiotics is partly reflected by the excretion of the respective antibiotics and their subsequent occurrence in wastewater. Their quantitative reduction in wastewater treatment reflects their potential environmental as well as human impact, the latter due to the use of the recipient water for domestic purposes and for irrigation. Information of the occurrence and reduction of different classes of antibiotics in wastewater treatment is sparse, especially the particle bound fraction of these. Due to this, analyses of aqueous and particle bound antibiotics in untreated wastewater of four selected wastewater treatment plants (WWTPs) and their receiving water bodies was carried out in Durban, South Africa. The treatment step especially considered was the biological one, represented by activated sludge and trickling filters. The treatment further included secondary clarifiers and final chlorine disinfection. Composite samples were collected during the period February 2017 to May 2017 and analysed with online solid phase extraction – high performance liquid chromatography mass spectrometry (SPE-HPLC-MS). For the 13 assessed antibiotics, the limit of detection (LOD) and the limit of quantification (LOQ) ranged from 0.07 to 0.33 ng L−1 and 0.23 to 1.09 ng L−1 respectively, while the total percentage recovery was in the range of 51 to 111%. The percentage of individual antibiotics bound to the particulate fraction normally lost by sample (influent) filtration, if not analysed in parallel, was in the range of 2.6%–97.3% (n = 32). In this fraction (sludge from centrifuge sample), the concentration of bound antibiotics of all the target antibiotics were detected in the influent of all WWTP in concentration ranges between 1.3 ng L−1 (Azithromycin; AZI) to 81,748 ng L−1 (Ciprofloxacin; CIP). The antibiotics with the highest median concentrations in receiving water bodies of the respective WWTP were; Sulfamethoxazole; SUL (239 ng L−1) WWTP “K”, Ciprofloxacin; CIP (708 ng L−1) WWTP “S” and Albendazole; ALB (325 ng L−1 and 683 ng L−1) WWTP “P” and “I” respectively.The overall percentage removal efficiency for the four WWTPs ranged from 21% to 100%. The biological treatment steps, activated sludge and trickling filters, were effective in removing antibiotics especially with the trickling filter and the impact of the sedimentation stage after activated sludge treatment.

Removal of the heavy metal ion nickel (II) via an adsorption method using flower globular magnesium hydroxide.

To remove toxic Ni(II) ions from wastewater, a novel flower globular magnesium hydroxide (FGMH) was prepared by a gentle method using trisodium citrate as a crystal modifier. This material exhibited a high specific surface area. The synthesized products and adsorption mechanism for Ni(II) ions were examined by diverse characterization technologies and methods. FGMH was employed to remove Ni(II) ions by the adsorption method. The effects of various parameters, viz., the amount of adsorbent, contact time, temperature and pH, on the removal rate by the adsorbent were investigated in detail. The kinetic data fitted well with a pseudo-second-order model and experimental equilibrium adsorption data conformed to a Langmuir isotherm under optimized conditions. The optimal process parameters included 30 mg of FGMH, a 50 min contact time, pH values between 6.07 and 7.71 for the Ni(II) solution, and adsorption at room temperature for 50 mL of 80 mg/L Ni(II) solution. The percentage of removal efficiency was found to be above 92.64%, and the maximum adsorption capacity of MH was 287.11 mg/g under optimum adsorption conditions. The analyses indicated that the Ni(II) ions were chemisorbed on the FGMH surface.

Improving productivity and water quality of catfish, Clarias sp. cultured in an aquaponic ebb-tide system using different filtration

Intensive culture waste has containing high nitrogen and phosphor elements can cause a negative impact on the fish and aquatic environment. The purpose of this experiment to examine the survival, growth, biomass of catfish, vegetable biomass production, and water quality. The treatments of this experiment were A) catfish culture in aquaponic with settling tank filter; B) catfish culture in aquaponic with settling tank and aerobic tank filters; and C) catfish culture in aquaponic with settling tank, semi-anaerobic tank, and aerobic tank filters. Each treatment consisted of three replicates. The result showed that growth, survival, and biomass of catfish at B and C treatments were higher than that of A treatment (P<0.05). Vegetable production such as pakchoy, caisim, tomato, and eggplant at B and C treatments showed higher than that of A treatment (P<0.05). Percentage of removal efficiency (RE) such as nitrite, nitrate, total ammonia (TAN), phosphate, total dissolved solids (TDS), and total organic matter (TOM) at B and C treatments were higher compared to A treatment (P<0.05). Addition of a filter tank in the aquaponic system should be installed in order to increase fish and vegetable production and to keep water quality stable.

Use of broken brick to enhance the removal of nutrients in subsurface flow constructed wetlands receiving hospital wastewater.

Eight horizontal subsurface flow pilot scale artificial wetlands were constructed to evaluate the effectiveness of broken brick to remove nutrients from hospital wastewater. The average total suspended solids (TSS), 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), NH4-N, NO3-N, and phosphate percent removal efficiency of constructed wetlands were, respectively, 93.2%, 90.4%, 83.7%, 64%, 64.3%, 52.1% and 56.1% in the dry season and 89.7%, 85.8%, 82.9%, 66%, 62.7%, 56.1% and 59.5% in the rainy season. Broken brick bed wetlands provide better removal efficiency of TKN, ammonia, nitrate, and phosphate with an average removal rate of 73%, 71.3%, 79.6% and 77.1% in the dry season and 74.7%, 70.7%, 70.9% and 73.6% in the rainy season, respectively, and it provides better adsorption sites for ammonium, nitrate, and phosphate. Typha with the broken brick bed significantly improved (P < 0.05) the treatment performance of the constructed wetland systems for the removal of ammonia, nitrate, and phosphate. The seasonal variation could not significantly influence the removal of all the pollutants, but better performance of nitrate and phosphate was achieved in a dry season. Use of locally available broken brick as a substrate media can increase the nutrient removal efficiency of wetlands at a cheaper cost when applied in full scale constructed wetlands.

Chitosan/Ag-hydroxyapatite nanocomposite beads as a potential adsorbent for the efficient removal of toxic aquatic pollutants

In the present study, the potential of synthesized chitosan/Ag-substituted hydroxyapatite nanocomposite beads to remove basic dye, heavy metal and microbes from aqueous solutions was investigated. Beads were prepared in different ratios via embedding of Ag-hydroxyapatite (Ag-HA) into chitosan (CS) solution. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) in order to get an insight of the functional groups and morphology. Batch adsorption studies were conducted with copper ions (Cu (II)) and rhodamine B (RhB) dye by changing several parameters such as Ag-HA to Cs ratio, contact time, solution pH and initial concentration of pollutants. The antibacterial efficiency of beads was tested under dynamic contact conditions against commonly found bacteria in water, Escherichia coli. The adsorption isotherm data were best fitted with Langmuir model. The maximum Langmuir adsorption capabilities for Cu (II) ions and rhodamine B were found to be 40.11 mg/g and 127.61 mg/g, respectively. The adsorption process could be best described by pseudo-second-order kinetic model for both rhodamine B and Cu(II). The percentage removal efficiency of Cu (II) and rhodamine B from tap water and untreated river water ranged from 86.7 to 94.4% along with 99.99% of decontamination of microbial load.

Removal of Cadmium (II) from Aqueous Medium Using Vigna radiata Leave Biomass: Equilibrium Isotherms, Kinetics and Thermodynamics

Abstract In the present study, a novel biosorbent Vigna radiata leaves biomass (L. biomass) was utilized for cadmium (II) extraction from aqueous medium. Cadmium (II) free and cadmium (II) loaded L. biomass was analyzed by Fourier transform infrared (FTIR) spectroscopy. Adsorption of cadmium (II) from aqueous medium was studied under various conditions such as adsorbent dose, agitation time, pH and temperature of the medium to optimize the process variables. Different models including Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (DR) were used to elaborate the insight of adsorption process. Best interpretation of biosorption process was given by Langmuir model. Value of maximum adsorption capacity (qm) calculated from Langmuir isotherm model was found to be 13.44 mg/g. Results indicated the establishment of physical interaction between cadmium (II) ions and functional groups of L. biomass. Kinetic study for adsorption of cadmium (II) ions on L. biomass was done by applying pseudo first order, pseudo second order, elovich and intra-particles diffusion models. Biosorption process best followed the pseudo second order kinetics. Value of standard Gibbs energy (ΔG°) and standard enthalpy change (ΔH°) showed the feasibility, spontaneity and endothermic nature of adsorption process. Percentage removal efficiency of L. biomass for cadmium (II) was successfully maintained for four cycles. Biomass has a potential to be used as an efficient adsorbent for the removal of cadmium (II) from different polluted water samples.

Kinetics and pathway of biodegradation of dibutyl phthalate by Pleurotus ostreatus

Dibutyl phthalate (DBP) is a plasticizer, whose presence in the environment as a pollutant has attained a great deal of attention due to its reported association with endocrine system disturbances on animals. Growth parameters, glucose uptake, percentage of removal efficiency (%E) of DBP, biodegradation constant of DBP (k) and half-life of DBP biodegradation (t1/2) were evaluated for Pleurotus ostreatus grown on media containing glucose and different concentrations of DBP (0, 500 and 1000 mg l−1). P. ostreatus degraded 99.6 % and 94 % of 500 and 1000 mg of DBP l−1 after 312 h and 504 h, respectively. The k was 0.0155 h−1 and 0.0043 h−1 for 500 and 1000 mg of DBP l−1, respectively. t1/2 was 44.7 h and 161 h for 500 and 1000 mg of DBP l−1, respectively. Intermediate compounds of biodegraded DBP were identified by GC-MS and a DBP biodegradation pathway was proposed using quantum chemical calculation. DBP might be metabolized to benzene and acetyl acetate, the first would be oxidated to muconic acid and the latter would enter into the Krebs cycle. P. ostreatus has the ability to degrade DBP and utilizes it as source of carbon and energy.

Recovery Ion Hg2+ dari Limbah Cair Industri Penambangan Emas Rakyat dengan Metode Presipitasi Sulfida dan Hidroksida

Unlicensed gold mining activities (PETI) using mercury (Hg) as a gold element binder is called the amalgamation process. Mercury is a heavy metal toxic. The use of mercury can potentially cause pollution in environment, especially the aquatic environment. For overcoming the heavy metals mercury in liquid waste, it needs an alternative wastewater treatment method called chemical precipitation. This study is aimed to recover Hg2+ ions from liquid wastes by using sulphide precipitation and hydroxide methods. This research studied the effect of pH on Hg ions which is deposited in the precipitation process and found out the rate of Hg precipitation formation. Precipitation was done by using sodium sulphide (Na2S) 0.3 M and Ca(OH)2 0.004 M as a precipitation agent with rapid mixing speed for about 200 rpm for 3 minutes and continued with slow mixing for about 40 rpm for 30 minutes. Then, just let the liquid sample be for 24 hours to precipate the precipitate formed. The results show that precipitation method by using a Na2S solution can decrease the content of Hg in HgCl2 synthetic waste. An optimum mass of HgS precipitate of 0,0458 g was achieved pH 9 for 200 mL of wastewater liquid with a removal efficiency percentage up to 99.81%. The concentration of mercury can be derived from 130 ppm to 0.25 ppm. The rate of formation of HgS precipitate was obtained 0.0004g/ hour. While, hydroxide precipitation method can decrease mercury level up to 90,11% at pH 12 and mass of Hg (OH)2 precipitate obtained is 0,2784 g. However, the result of EDX analysis of the precipitate of Hg (OH)2 shows that the content of Hg precipitate is just 0.281%.

Synthesis of S-ligand tethered cellulose nanofibers for efficient removal of Pb(II) and Cd(II) ions from synthetic and industrial wastewater

Cellulose nanofibers (CNFs) tethered with sulphur as anionic ligand were synthesized from medical absorbent cotton by dissolution with NaOH, CO(NH2)₂ followed by mechanical intrusion of sulphur from SC(NH₂)₂ at an elevated temperature. The solid-phase CNFs embedded with sulphur complexes possessed negative sites which were used to remove cationic metals viz., Pb(II) and Cd(II) from synthetic and industrial wastewater. The physicochemical properties of the CNFs were analyzed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), pH at point of zero charge (pHpzc) and X-ray photoelectron spectroscopy (XPS). Batch adsorption studies were conducted with synthetic wastewater to optimize the conditions for Pb(II) and Cd(II) removal by CNFs. Different adsorption kinetic models were applied to assess and define the adsorption mechanism. The maximum Langmuir adsorption capacity was found to be 1.16 and 0.82 mmol g−1 for Pb(II) and Cd(II) ions, respectively. Regeneration studies showed that the CNFs can be reused using 0.1 M NaOH as eluent. The percentage removal efficiency of different cationic metals by CNFs from untreated industrial wastewater ranged from ca. 90–98%.

Synthesis of novel magnetic nano-sorbent functionalized with N-methyl-D-glucamine by click chemistry and removal of boron with magnetic separation method

Click chemistry refers to a group of reactions that are fast, simple to use, easy to purify, versatile, regiospecific, and give high product yields. Therefore, a novel, efficient magnetic nano-sorbent based on N-methyl-D-glucamine attached to magnetic nanoparticles was prepared using click coupling method. Its boron sorption capacity was compared with N-methyl-D-glucamine direct attached nano-sorbent. The characterization of the magnetic sorbents was investigated by several techniques such as X-ray diffraction, scanning electron microscope, transmission electron microscope, dynamic light scattering, thermogravimetric analysis, Fourier transform infrared spectrophotometer, and vibrating sample magnetometer. The boron sorption capacity of sorbents was compared by studying various essential factors influencing the sorption, like sorbate concentration, sorbents dosage, pH of the solution, and contact time. Langmuir and Freundlich and Dubinin-Radushkevich adsorption isotherms models were applied. Percent removal and sorption capacities efficiencies of sorbents obtained with direct and click coupling are found to be 49.5%, 98.7% and 6.68 mg/g, 13.44 mg/g respectively. Both sorbents have been found to be compatible with Langmuir isotherm, and the boron sorption kinetics conforms to the pseudo second order kinetics. The reusability study of sorbents was carried out five times for boron sorption and desorption.

Bioaccumulative activity of Ludwigia peploides on heavy metals-contaminated water

Abstract Heavy metal pollution of soil and water has become a serious environmental problem in recent decades. This study was carried out to investigate the Ludwigia peploides bioremediation activity against heavy metals-contaminated water. The plant Ludwigia peploides was collected from Asa River, in Ilorin Kwara State, alongside with the water sample. The pond water collected was distributed into six (6) different 5-litre buckets (Grouped A–F) in which the plant was cultivated for experimentation within a period of 28 days in the laboratory. Group A served as the control which contained only the natural environment of the plant, Groups B, C and C contained added 5.0 mg/litre Cu, Pb and Cr respectively in the form of CuSO4, PbNO3 and K2Cr2O7 respectively. Group E contained 0.5 mg/litre added Cd in the form of CdNO3 while Group F contained 500 mg/litre added Zn in the form of ZnSO4. The Percentage removal efficiency, Translocation factor, Bioconcentration factor and Bioaccumulation coefficient of the plant leaves and roots were evaluated. Also, activities of superoxide dismutase (SOD) and catalase; MDA, chlorophyll and proximate composition of the leaves were evaluated. There was significant increase ( p 0 . 05 ) in the chlorophyll-a content of all the test samples when compared with the control. There was also significant increase in the MDA concentration in the plant leaves and in the catalase specific activity of the plant cultivated with chromium, lead and cadmium. There was significant reduction ( p 0 . 05 ) in SOD activity of the plant cultivated with chromium and zinc at the early stage of cultivation. The translocation factor (TF) of the plant ranges between 0.10–2.11 while the bioaccumulative coefficient (BAC) ranges between 0.10 and 2.68. We therefore conclude that the roots of Ludwigia peploides have ability to remove copper from contaminated water effectively, and to a moderate extent chromium, lead and cadmium. Also, the leaves of the plant absorb high percentage of chromium from the contaminated environment. This study evidenced that Ludwigia peploides may serve as an effective bioremediation agent for correcting contaminated water.

Performance Assessment of Biological Wastewater Treatment at WUPA Wastewater Treatment Plant, Abuja, Nigeria

Biological treatment of wastewater from Wupa Wastewater Treatment Plant, Abuja was investigated. Wastewater samples were collected from the inlet and effluent point (before and after the ultra violet radiation unit) of the treatment plant. The physicochemical parameters; temperature, pH, conductivity, total dissolved solids (TDS), total suspended solids (TSS) and dissolved oxygen (DO) were measured. The Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) were obtained from samples collected from the influent and effluent points using Standard methods specified by the American Public Health Association (APHA). The water samples were also analysed for the presence of bacterial organisms via Total Coliform Count (TCC), Total Bacteriological Count (TBC) and Faecal Count (FC). At the end of the analysis, the percentage removal efficiency of the ultra violet radiation for TCC, TBC and FC were calculated. Results showed that the mean removal efficiency for TCC, TBC and FC were 99.6% , 89.9% and 98.9% respectively; all within the permissible limit of World Health Organization and Federal Ministry of Environment. There was a reduction of 81.5% in COD, 98.9% in BOD which met the required effluent standards. There was significant differences between the pH, TSS, DO, COD and BOD of the influent and effluent (P&lt;0.05). These results showed that there is an urgent need for appropriate steps to be taken for proper management and sanitation of the wastewater before discharging it to the stream, to ensure total conformity with the approved standards.

Comparison of Reed and Water Lettuce in Constructed Wetlands for Wastewater Treatment.

In the present study two designs, vertical and horizontal systems, were used and two different plant species, Water Lettuce (Pistia stratiotes) and Reed plant (Phragmites karka), compared for their removal efficiency. The vertical system appeared to be more stable and efficient for almost all the parameters. The vertical system, planted with Water Lettuce, showed percentage removal efficiency for BOD, phosphate and chloride as 82, 95.4, and 51, respectively, whereas turbidity and total suspended solids removal efficiencies were almost the same. However, fecal coliform removal by the Water Lettuce was 98.8% for both designs (vertical and horizontal), showing the ability of the plant to uptake nutrients and release toxins for pathogen disinfection. It appears that the vertical system could be the better option, planted with Water Lettuce, or with both plants in a co-culture environment.

Mineralization of high concentrations of the endocrine disruptor dibutyl phthalate by Fusarium culmorum.

Dibutyl phthalate (DBP) is a widely used plasticizer, whose presence in the environment as a pollutant raises concern because of its endocrine-disrupting toxicity. Growth kinetics, glucose uptake, biodegradation constant of DBP (k), half-life of DBP biodegradation (t1/2) and percentage of removal efficiency (%E) were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DBP (500 and 1000mg/l). Intermediate compounds of biodegraded DBP were identified by GC-MS and a novel DBP biodegradation pathway was proposed on the basis of the intermolecular flow of electrons of the intermediates identified using quantum chemical modeling. F. culmorum degraded 99% of both 1000 and 500mg of DBP/l after an incubation period of 168 and 228h, respectively. %E was 99.5 and 99.3 for 1000 and 500mg of DBP/l, respectively. The k was 0.0164 and 0.0231h-1 for 500 and 1000mg of DBP/l, respectively. DBP was fully metabolized to fumaric and malic acids, which are compounds that enter into the Krebs cycle. F. culmorum has a promising ability for bioremediation of environments polluted with DBP because it efficiently degrades DBP and uses high concentrations of this compound as carbon and energy source.

Performance of a large-scale wetland treatment system in treating tailwater from a sewage treatment plant

Water quality standards pertaining to effluent from sewage treatment plants (STPs) in China have become more stringent, requiring upgrading of STPs and entailing huge capital expenditure. Wetland treatment systems (WTSs) are a low-cost and highly efficient approach for deep purification of tailwater from STPs. The Hongze WTS (HZ-WTS), a large-scale surface-flow constructed wetland, with a total area of 55.58ha and a treatment capacity of 4×104m3day–1, was built for the disposal of tailwater from STPs. The aim of the present study was to evaluate the performance of HZ-WTP with regard to seasonal variations and to compare treatment costs with those of other STPs. The performance of the HZ-WTS was evaluated in 2013 using online monitoring. HZ-WTS exhibited significant removal efficiency of ammonia nitrogen (NH4+-N), chemical oxygen demand and total phosphorus (mean±s.d., percentage removal efficiency 56.33±70.44, 55.64±18.58 and 88.44±22.71% respectively), whereas there was significant seasonal variation in the efficiency of NH4+-N removal. In addition, the average treatment cost was ¥0.17m–3, significantly lower than the corresponding value for other STPs. Therefore, WTSs are recommended for use with STPs in order to improve waste water quality in a cost-effective manner.

Experimental Evaluation of the Halophyte, Salicornia virginica, for Biomitigation of Dissolved Nutrients in Effluent from a Recirculating Aquaculture System for Marine Finfish

AbstractThe ability of the halophyte, Salicornia virginica, planted in drainage lysimeters to biomitigate dissolved nutrients in effluent from a recirculating aquaculture system (RAS) for marine finfish was evaluated. Seawater effluent from a RAS producing black sea bass, Centropristis striata (filtered to reduce total suspended solids), was used as irrigant. Plant growth and dissolved N and P removal were determined as a function of leachate fraction (LF%) – that is, proportion of irrigant that leaches from the plant‐substrate lysimeter. Lysimeters were irrigated weekly to produce 30, 40, and 50% LF. A control (unplanted) lysimeter was included at the 30% LF. Plant growth was excellent in all LF% treatments until Day 141 when salt buildup in the lysimeter substrate inhibited nutrient uptake. Salt accumulation was mitigated at higher LF%, so that plant biomass and net removal (μg) of dissolved N and P by the p‐s lysimeter remained higher (P &lt; 0.05) at the 40 and 50% than at the 30% LF. On Day 141, percent removal efficiency at the 50% LF was 79.2% for inorganic N and 73.9% for total phosphorus. Through Day 355, substrate salinity was minimized and plant biomass and nutrient removal were maximized at the 50% LF. S. virginica is an effective biofilter for dissolved nutrients in effluent from an RAS for marine finfish.

A novel biodegradation pathway of the endocrine-disruptor di(2-ethyl hexyl) phthalate by Pleurotus ostreatus based on quantum chemical investigation

Di(2-ethyl hexyl) phthalate (DEHP) is a plasticizer that interfere with endocrine systems in mammals. Growth parameters for Pleurotus ostreatus grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000mg/L) were evaluated. The highest biomass production was observed in medium supplemented with 1000mg of DEHP/L. Half-life of DEHP biodegradation, biodegradation constant of DEHP, and percentage of removal efficiency (%E) were also determined. P. ostreatus degraded 100% of DEHP after 504h. %E was 99.3% and 98.4% for 500 and 1000mg of DEHP/L, respectively. Intermediate compounds of biodegraded DEHP were identified by GC-MS and a DEHP biodegradation pathway was proposed using quantum chemical investigation. DEHP might be metabolized through three pathways; a de-esterification pathway, an oxidation pathway and an oxidation-hydrolysis pathway, forming phthalic acid, acetic acid and butanediol, respectively. P. ostreatus degrades and uses (as carbon and energy source) high concentrations of DEHP.