Anammox for ammonia removal from pig manure effluents: Effect of organic matter content on process performance

The anammox process, under different organic loading rates (COD), was evaluated using a semi-continuous UASB reactor at 37 °C. Three different substrates were used: initially, synthetic wastewater, and later, two different pig manure effluents (after UASB-post-digestion and after partial oxidation) diluted with synthetic wastewater. High ammonium removal was achieved, up to 92.1 ± 4.9% for diluted UASB-post-digested effluent (95 mg COD L^?1) and up to 98.5 ± 0.8% for diluted partially oxidized effluent (121 mg COD L^?1). Mass balance clearly showed that an increase in organic loading (from 95 mg COD L^?1 to 237 mg COD L^?1 and from 121 mg COD L^?1 to 290 mg COD L^?1 for the UASB-post-digested effluent and the partially oxidized effluent, respectively) negatively affected the anammox process and facilitated heterotrophic denitrification. Partial oxidation as a pre-treatment method improved ammonium removal at high organic matter concentration. Up to threshold organic load concentration of 142 mg COD L^?1 of UASB-post-digested effluent and 242 mg COD L^?1 of partially oxidized effluent, no effect of organic loading on ammonia removal was registered (ammonium removal was above 80%). However, COD concentrations above 237 mg L^?1 (loading rate of 112 mg COD L^?1 day^?1) for post-digested effluent and above 290 mg L^?1 (loading rate of 136 mg COD L^?1 day^?1) for partially oxidized effluent resulted in complete cease of ammonium removal. Results obtained showed that, denitrification and anammox process were simultaneously occurring in the reactor. Denitrification became the dominant ammonium removal process when the COD loading was increased.     

Effects of vegetation,limestone and aeration on nitritation,anammox and denitrification in wetland treatment systems

Integration of partial nitrification (nitritation) and anaerobic ammonium oxidation (anammox) in constructed wetlands creates a sustainable design for nitrogen removal. Three wetland treatment systems were operated with synthetic wastewater (60 mg NH₃–N L^?1) in a batch mode of fill – 1-week reaction – drain. Each treatment system had a surface flow wetland (unplanted, planted, and planted plus aerated, respectively) with a rooting substrate of sandy loam and limestone pellets, followed by an unplanted subsurface flow wetland. Meanwhile, three surface flow wetlands with a substrate of sandy loam and pavestone were operated in parallel to the former surface flow wetlands. Influent and effluent were monitored weekly for five cycles. Aeration reduced nitrogen removal due to hindered nitrate reduction. Vegetation maintained pH near neutral and moderate dissolved oxygen, significantly improved ammonia removal by anammox, and had higher TN removal due to coexistence of anammox and denitrification in anaerobic biofilm layers. Nitrite production was at a peak at the residence time of 4–5 d. Relative to pavestone, limestone increased the nitrite mass production peak by 97%. The subsurface flow wetlands removed nitrogen via nitritation and anammox, having an anammox activity of up to 2.4 g N m^?3 d^?1 over a startup operation of two months.     

Nitrogen transformations in vertical flow systems with and without rice (Oryza sativa) studied with a high-resolution soil–water profiler

Nitrogen transformations were studied in flooded and non-flooded vertical flow columns with and without a rice plant. Influent (average concentration: NH₄⁺-N: 40 mg L^?1; NO₃^?-N: 0.15 mg L^?1; and NO₂^?-N: 4.0 mg L^?1) was supplied at 1.25 cm d^?1 during stage 1 (20 May–5 August) and at 2.50 cm d^?1 at stage 2 (6 August–26 October), which resulted in an average nitrogen loading of 156 g m^?2 during the entire experimental period. Total nitrogen (T-N) removal efficiencies exceeded 90% in vertical flow systems with rice plants. Nitrogen assimilated by the rice plants in the flooded column accounted for 60% of the total input nitrogen, while that in the non-flooded column accounted for 36% of the total input. The remaining nitrogen appeared to be removed through biogeochemical pathways. Although some nitrogen flowed out, most input nitrogen was also removed even in the flooded and non-flooded unplanted columns.A high-resolution vertical distribution investigation showed the changes of nitrogen forms in soil water. In the flooded condition, there were high ammonium and high nitrite concentrations in the upper layers. The concentrations of ammonium and nitrite simultaneously decreased with depth increasing, suggesting that anaerobic ammonia oxidation (anammox) may occur in these anaerobic conditions. In contrast, the distributions of nitrogen in the non-flooded columns with elevated water level suggested that nitrification–denitrification route was the major removal mechanism, whether or not rice plants were present.     

Effects of Zn2+ and niflumic acid on photosynthesis in Glycine soja and Glycine max seedlings under NaCl stress

The effects of two anion/Cl^? channel inhibitors, Zn²⁺ and niflumic acid (NA), on seedling photosynthetic and fluorescent parameters of two Glycine soja populations (salt-tolerant BB52; salt-sensitive N23227) and Glycine max cultivar (salt-tolerant Lee68) were studied and compared under salt stress. Treatments with Zn²⁺ and NA only (10, 20 μmol L^?1) were also imposed for comparisons. Results showed that, there were non-toxic and non-nutritional effects of Zn²⁺ and NA treatments alone on seed germination and seedling growth of soybeans. Under 150 mmol L^?1 NaCl for 6 d, leaf chlorophyll and carotenoid contents, net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), transpiration rate (Tr), and the maximum photochemical efficiency of photosystem II (PS II) (F_v/F_m) except the stomatal limitation (Ls) significantly decreased in three kinds of soybean seedlings when compared with their control plants. The NaCl stress plus additional 20 μmol L^?1 Zn showed an obvious enhancement of leaf chlorophyll and carotenoid contents, P_n, G_s, C_i and Tr, especially for the G. max cultivar Lee68, but the supplementation of 20 μmol L^?1 NA showed the reverse effects.     

Effect of hydraulic retention time on the treatment of secondary effluent in a subsurface flow constructed wetland

This study evaluates the potential of subsurface flow (SSF) constructed wetlands (CWs) for tertiary treatment of wastewater at four shorter HRTs (1–4 days). The CWs were planted with Typha angustata, which was observed in our earlier study to be more efficient than Phragmites karka and Scirpus littoralis. The CWs comprised four rectangular treatment cells (2.14 m × 0.76 m × 0.61 m) filled with layers of gravel of two different sizes (approximately 2.5 cm and 1.5 cm diameter) to a depth of 0.61 m. The inflow rates of the secondary effluent in the four cells were accordingly fixed at 300 L d^?1, 150 L d^?1, 100 L d^?1 and 75 L d^?1, respectively, for 1, 2, 3 and 4 days HRT. The hydraulic loads ranged between 59.05 mm d^?1 and 236.22 mm d^?1.The wastewater inflow into the CW system as well as the treated effluent were analyzed, using standard methods, at regular intervals for various forms of nitrogen (NH₄-N, NO₃-N and TKN), orthophosphate-P and organic matter (BOD and COD) concentrations over a period of five weeks after the development of a dense stand.The higher HRT of 4 days not only helped maximum removal of all the pollutants but also maintained the stability of the treatment efficiency throughout the monitoring period. For the nutrients (NH₄-N, NO₃-N and TKN), HRT played a more significant role in their removal than in case of organic matter (BOD₃ and COD). More than 90% of NO₃-N and TKN and 100% of NH₄-N were removed from the wastewater at 4 days HRT.At lower HRTs, the mass loading rate was higher with greater fluctuation. However mass reduction efficiency of the T. angustata CW for all forms of nitrogen was >80% with the HRTs of 2, 3 and 4 days.     

Purification,kinetic and thermodynamic characterization of soluble acid invertase from sugarcane (Saccharum officinarum L.)

We report for the first time kinetic and thermodynamic properties of soluble acid invertase (SAI) of sugarcane (Saccharum officinarum L.) salt sensitive local cultivar CP 77-400 (CP-77). The SAI was purified to apparent homogeneity on FPLC system. The crude enzyme was about 13 fold purified and recovery of SAI was 35%. The invertase was monomeric in nature and its native molecular mass on gel filtration and subunit mass on SDS-PAGE was 28 kDa. SAI was highly acidic having an optimum pH lower than 2. The acidic limb was missing. Proton transfer (donation and receiving) during catalysis was controlled by the basic limb having a pKa of 2.4. Carboxyl groups were involved in proton transfer during catalysis. The kinetic constants for sucrose hydrolysis by SAI were determined to be: k_m = 55 mg ml^?1, k_cat = 21 s^?1, k_cat/k_m = 0.38, while the thermodynamic parameters were: ΔH* = 52.6 kJ mol^?1, ΔG* = 71.2 kJ mol^?1, ΔS* = ?57 J mol^?1 K^?1, ΔG*_E–S = 10.8 kJ mol^?1 and ΔG*_E–T = 2.6 kJ mol^?1. The kinetics and thermodynamics of irreversible thermal denaturation at various temperatures 53–63 °C were also determined. The half -life of SAI at 53 and 63 °C was 112 and 10 min, respectively. At 55 °C, surprisingly the half -life increased to twice that at 53 °C. ΔG*, ΔH* and ΔS* of irreversible thermal stability of SAI at 55 °C were 107.7 kJ mol^?1, 276.04 kJ mol^?1 and 513 J mol^?1K^?1, respectively.     

CBOD5 treatment using the marshland upwelling system

Five-day carbonaceous biochemical oxygen demand (CBOD₅) removal efficiency was evaluated for the marshland upwelling system (MUS) under both intermediate and saltwater conditions. The MUS treated decentralized wastewater from two private camps and a public restroom in the Grand Bay National Estuarine Research Reserve, Moss Point, Mississippi, and one private camp in the Barataria Terrebonne National Estuary, along Bayou Segnette, Louisiana. Raw wastewater was injected into the surrounding subsurface at a depth of 3.8 or 4.3 m. Various injection flow rates and frequencies were tested in addition to a synthetic wastewater trial. All trials followed a first-order background corrected removal equation, resulting in removal constants ranging from 0.49 to 3.32 m^?1 and predicted surface concentrations from 5.7 to 33.0 mg L^?1. CBOD₅ (unfiltered) influent concentrations of 282 ± 173 mg L^?1 were reduced to an overall effluent mean of 13 ± 13 mg L^?1 by a vector distance of 7 m at Moss Point and from 365 ± 151 mg L^?1 to 3.6 ± 7.6 mg L^?1 by a vector distance of 6 m for Bayou Segnette. Of seven trials, only one failed to achieve effluent CBOD₅ levels below a National Pollutant Discharge Elimination System (NPDES) standard level of 25 mg L^?1.     

Operation of an Anammox SBR in the presence of two broad-spectrum antibiotics

The feasibility of the anaerobic ammonium oxidation (Anammox) process to treat wastewaters containing antibiotics was studied in this work. Concentrations ranging from 100 to 1000 mg L^?1 for tetracycline hydrochloride and from 250 to 1000 mg L^?1 for chloramphenicol were tested in batch assays. A strong inhibitory effect was observed for both antibiotics.A concentration of 20 mg L^?1 of chloramphenicol was continuously added to an Anammox Sequential Batch Reactor (SBR) system, causing a decrease of the nitrogen removal efficiency of 25%. The Specific Anammox Activity (SAA) of the biomass also decreased from 0.25 to 0.05 g N (g VSS d)^?1. Similar effects were observed when 50 mg L^?1 of tetracycline hydrochloride were continuously fed. Both antibiotics did not cause any changes in the physical properties of the biomass. A previous degradation step could be necessary in order to treat wastewaters containing inhibitory concentrations of antibiotics by the Anammox process.     

Poly(3-hydroxybutyrate) production by Cupriavidus necator using waste glycerol

Polyhydroxyalkanoates (PHAs) have been recognized as good substitutes for the non-biodegradable petrochemically produced polymers. However, their high (real or estimated) current production cost limits their industrial applications. This work exploits two strategies to enhance PHAs substitution potential: the increase in PHA volumetric productivity in high density cultures and the use of waste glycerol (GRP), a by-product from the biodiesel industry, as primary carbon source for cell growth and polymer synthesis. Cupriavidus necator DSM 545 was used to accumulate poly(3-hydroxybutyrate) (P(3HB)) from GRP and from commercial glycerol (PG) as control substrate. On PG, productivities between 0.6 g_PHB L^?1 h^?1 and 1.5 g_PHB L^?1 h^?1 were attained. The maximum cell DW was 82.5 g_DW L^?1, the P(3HB) content being 62%. When GRP was used, 68.8 g_DW L^?1 with a P(3HB) accumulation of 38% resulting in a final productivity of 0.84 g_PHB L^?1 h^?1 was obtained. By decreasing the biomass concentration at which accumulation was triggered, a productivity of 1.1 g_PHB L^?1 h^?1 (50% P(3HB), w/w) was attained using GRP. P(3HB) molecular weights (M_w) ranged from 7.9 × 10⁵ to 9.6 × 10⁵ Da.     

Continuous production of selenomethionine-enriched Chlorella sorokiniana biomass in a photobioreactor

This article describes the enrichment of the fresh-water green microalga Chlorella sorokiniana in selenomethionine (SeMet). The microalga was cultivated in a 2.2 L glass-vessel photobioreactor, in a culture medium supplemented with selenate (SeO₄^2?) concentrations ranging from 5 to 50 mg L^?1. Although selenate exposure lowered culture viability, C. sorokiniana grew well at all tested selenate concentrations, however cultures supplemented with 50 mg L^?1 selenate did not remain stable at steady state. A suitable selenate concentration in fresh culture medium for continuous operation was determined, which allowed stable long-term cultivation at steady state and maximal SeMet productivity. In order to do that, the effect of dilution rate on biomass productivity, viability and SeMet content of C. sorokiniana at several selenate concentrations were determined in the photobioreactor. A maximal SeMet productivity of 21 μg L^?1 day^?1 was obtained with 40 mg L^?1 selenate in the culture medium. Then a continuous cultivation process at several dilution rates was performed at 40 mg L^?1 selenate obtaining a maximum of 246 μg L^?1 day^?1 SeMet at a low dilution rate of 0.49 day^?1, calculated on total daily effluent volume. This paper describes for the first time an efficient long-term continuous cultivation of C. sorokiniana for the production of biomass enriched in the high value amino acid SeMet, at laboratory scale.     

Mass balance of nitrogen in constructed mangrove wetlands receiving ammonium-rich wastewater: Effects of tidal regime and carbon supply

A series of computer-controlled mangrove tide-tanks planted with Kandelia candel was constructed to investigate the removal and transformation of ammonium–nitrogen under two tidal regimes: (i) 12-h wet/12-h dry (long tidal regime) and (ii) 6-h wet/6-h dry/6-h wet/6-h dry daily (short tidal regime). All tanks were irrigated with NH₄Cl solution for nine water cycles (each cycle lasted for 5 weeks) at an amount of around 2.1 g NH₄Cl (equivalent to 0.52 g N) per tank per cycle. During the experiment, total Kjeldahl nitrogen (TKN), inorganic nitrogen (N) (NH₄⁺–, NO₂^?–, and NO₃^?–N) and carbon were completely removed by the mangrove system. The added NH₄⁺–N was not detected in tidal water or accumulated in sediment. The mass balance of nitrogen showed that the discharge of ammonium-rich wastewater to mangrove wetlands enhanced microbial nitrogen transformation, particularly nitrification and denitrification processes, with 15–30% of the total nitrogen inputs returned to atmosphere as N₂ gas. Growth of K. candel and macroalgae was stimulated by ammonium addition, and up to 3 and 7% of total N inputs were assimilated in plant and algal tissues, respectively. Constructed mangrove wetlands with short tidal regime had higher numbers of nitrifiers and significantly lower content of ammonium that those with long tidal regime. On the other hand, higher populations of denitrifiers and lower nitrate were found in mangroves with long tidal regime and with glucose addition.     

Ethanol addition as a strategy for start-up and acclimation of an AnSBBR for the treatment of landfill leachate

This study evaluated the ethanol addition as a strategy for start-up and acclimation of a pilot scale (1300 L) anaerobic sequencing batch biofilm reactor (AnSBBR) for the treatment of municipal landfill leachate with seasonal biodegradability variations. The treatment was carried out at ambient temperature (23.8 ± 2.1 °C) in the landfill area. In a first attempt, the leachate collected directly from landfill showed to be predominantly recalcitrant to anaerobic treatment and the acclimation was not possible. In a second attempt, adding ethanol to leachate, the reactor was successfully acclimated. After acclimation, without ethanol addition, the COD_Total influent ranged from 4970 to 13040 mg L^?1 and the removal efficiencies ranged from 12.1% to 70.7%. A final test was carried out increasing the ammonia and free-ammonia concentration from 2486 mgN L^?1 and 184 mgN L^?1 to 4519 mgN L^?1 and 634 mgN L^?1, respectively, with no expressive inhibition verified. The start-up strategy was found to be feasible, providing the acclimation of the biomass in the AnSBBR, and maintaining the biomass active even when the leachate was recalcitrant.     

Treatment of high-strength wastewater in tropical vertical flow constructed wetlands planted with Typha angustifolia and Cyperus involucratus

The ability of vertical flow (VF) constructed wetland systems to treat high-strength (ca. 300 mg L^?1 of COD and ca. 300 mg L^?1 total-nitrogen) wastewater under tropical climatic conditions was studied during a 5-month period. Nine 0.8-m diameter experimental VF units (depth 0.6 m) were used: three units were planted with Typha angustifolia L., another three units were planted with Cyperus involucratus Rottb and three units were unplanted. Each set of units were operated at hydraulic loading rates (HLRs) of 20, 50 and 80 mm d^?1. Cyperus produced more shoots and biomass than the Typha, which was probably stressed because of lack of water. The high evapotranspirative water loss from the Cyperus systems resulted in higher effluent concentrations of COD and total-P, but the mass removal of COD did not differ significantly between planted and unplanted systems. Average mass removal rates of COD, TKN and total-P at a HLR of 80 mm d^?1 were 17.8, 15.4 and 0.69 g m^?2 d^?1. The first-order removal rate constants at a HLR of 80 mm d^?1 for COD, TKN and total-P were 49.8, 30.1 and 13.5 m year^?1, respectively, which is in the higher range of k-values reported in the literature. The oxygen transfer rates were ca. 80 g m^?2 d^?1 in the planted systems as opposed to ca. 60 g m^?2 d^?1 in the unplanted systems. The number of Nitrosomonas was two to three orders of magnitude higher in the planted systems compared to the unplanted systems. Planted systems thus had significantly higher removal rates of nitrogen and phosphorus, higher oxygen transfer rates, and higher quantities of ammonia-oxidizing bacteria. None of the systems did, however, fully nitrify the wastewater, even at low loading rates. The vertical filters did not provide sufficient contact time between the wastewater and the biofilm on the gravel medium of the filters probably because of the shallow bed depth (0.6 m) and the coarse texture of the gravel. It is concluded that vertical flow constructed wetland systems have a high capacity to treat high-strength wastewater in tropical climates. The gravel and sand matrix of the vertical filter must, however, be designed in a way so that the pulse-loaded wastewater can pass through the filter medium at a speed that will allow the water to drain before the next dose arrives whilst at the same time holding the water back long enough to allow sufficient contact with the biofilm on the filter medium.     

Anaerobic treatment of saline wastewater by Halanaerobium lacusrosei

An upflow anaerobic packed bed reactor was operated continuously with synthetic saline wastewater at different initial COD concentrations (COD₀ = 1900–6300 mg/L), salt concentrations (0–5%, w/v) and hydraulic retention times (θ_H = 11–30 h) to investigate the effect of those operating parameters on COD removal from saline synthetic wastewater. Anaerobic salt tolerant bacteria, Halanaerobium lacusrosei, were used as dominant microbial culture in the process. The percent COD removal reached up to 94% at COD₀ = 1900 mg/L, 19 h hydraulic retention time and 3% salt concentration. No substrate inhibition effect was observed at high feed CODs. Increasing hydraulic retention time from 11 h to 30 h resulted in a substantial improvement in the COD removal from 60% to 84% at around COD₀ = 3400 mg/L and 3% salt concentration. Salt inhibition effect on COD utilization was observed at above 3% salt concentration. Modified Stover–Kincannon model was applied to the experimental data to determine the biokinetic coefficients. Saturation value constant, and maximum utilization rate constant of Stover–Kincannon model for COD were determined as K_B = 5.3 g/L day, U_max = 7.05 g/L day, respectively.     

Purification and characterization of a new laccase from Shiraia sp.SUPER-H168

A new laccase from Shiraia sp.SUPER-H168 was purified by ion exchange column chromatography and gel permeation chromatography and the apparent molecular mass of this enzyme was 70.78 kDa, as determined by MALDI/TOF-MS. The optimum pH value of the purified laccase was 4, 6, 5.5 and 3 with 2,6-dimethoxyphenol (DMP), syringaldazine, guaiacol and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) as substrates, respectively. The optimum temperature of the purified laccase was 50 °C using DMP, syringaldazine and guaiacol as substrates, but 60 °C for ABTS. Inhibitors and metal ions of SDS, NaN₃, Ag⁺ and Fe³⁺ showed inhibition on enzyme activity of 10.22%, 7.86%, 8.13% and 67.50%, respectively. Fe²⁺ completely inhibited the purified laccase. The K_cat/K_m values of the purified laccase toward DMP, ABTS guaiacol and syringaldazine were 3.99 × 10⁶, 3.74 × 10⁷, 8.01 × 10⁴ and 2.35 × 10⁷ mol^?1 L S^?1, respectively. The N-terminal amino acid sequence of the purified laccase showed 36.4% similarity to Pleurotus ostrestus. Approximately 66% of the Acid Blue 129 (100 mg L^?1) was decolorized by 2.5 U of the purified laccase after a 120 min incubation at 50 °C. Acid Red 1 (20 mg L^?1) and Reactive Black 5 (50 mg L^?1) were decolorized by the purified laccase after the addition of Acid Blue 129 (100 mg L^?1).     

Phenol and sulfide oxidation in a denitrifying biofilm reactor and its microbial community analysis

A microbial consortium attached onto a polyethylene support was used to evaluate the simultaneous oxidation of sulfide and phenol by denitrification. The phenol, sulfide and nitrate loading rates applied to an inverse fluidized bed reactor were up to 168 mg phenol–C/(l d), 37 mg S^2?/(l d) and 168 mg NO₃^?–N/(l d), respectively. Under steady state operation the consumption efficiencies of phenol, sulfide and nitrate were 100%. The N₂ yield (g N₂/g NO₃^?–N) was 0.89. The phenol was mineralized resulting in a yield of 0.82 g bicarbonate–C/g phenol–C and sulfide was completely oxidized to sulfate with a yield of 0.99 g SO₄^2?–S/g S^2?. 16S rRNA gene-based microbial community analysis of the denitrifying biofilm showed the presence of Thauera aromatica, Thiobacillus denitrificans, Thiobacillus sajanensis and Thiobacillus sp. This is the first work reporting the simultaneous oxidation of sulfide and phenol in a denitrifying biofilm reactor.     

Physiological responses of Phragmites australis to wastewater with different chemical oxygen demands

Constructed wetlands have been widely used to treat various wastewaters with large differences in their concentration of pollutants. The capability of wetland plants to resist these wastewaters is crucial for a wetland's healthy development. Phragmites australis has been shown to have the capability to grow in simulated wastewater containing a wide concentration of pollutants. In this study, the physiological responses of P. australis to simulated wastewaters with high chemical oxygen demands (CODs) were investigated in a bucket experiment. P. australis was incubated in buckets for 30 days at five treatments of 0, 100, 200, 400, and 800 mg L^?1 COD simulated wastewater. The net photosynthesis rate of the plants declined markedly with increasing COD levels. Proline and malondialdehyde (MDA) contents also increased dramatically. The plants further showed a unimodal pattern of superoxide dismutase (SOD) and peroxidase (POD) distribution along external COD values on the whole, indicating that high COD values (≥200 mg L^?1) can disrupt the normal metabolism of the plant. High COD levels (COD ≥ 400 mg L^?1) caused evident physiological changes in P. australis.     

Application of anaerobic–aerobic sequential treatment system to real textile wastewater for color and COD removal

A sequential anaerobic packed column reactor and an activated sludge unit was operated continuously for treatment of a textile industry wastewater, in Izmir, Turkey. Metal sponges were used as support material in anaerobic unit and pre-activated textile dyestuff biodegrading PDW facultative anaerobic bacterial culture was immobilized on the support particles. Effects of hydraulic retention times in anaerobic unit (θ_H anaerobic = 12–72 h) and initial COD concentration (COD₀ = 3000 ± 200 mg/L and 800 ± 100 mg/L) at θ_H anaerobic = 24 h on color and COD removal performance of the system were investigated. The results indicated that over 85% decolorization and about 90% COD removal efficiency can be obtained up to θ_H anaerobic = 48 h but higher retention times causes decreasing in decolorization efficiency. Operating the system with real wastewater without adding any nutrients at θ_H anaerobic = 24 h resulted in over 60% improvement in color removal in studied wastewater compared to existing treatment plant.     

Impact of in vitro CO2 enrichment and sugar deprivation on acclimatory responses of Phalaenopsis plantlets to ex vitro conditions

We assessed the effect of growth at either 400 μmol mol^?1 (ambient) or 1000 μmol mol^?1 (elevated) CO₂ and 0 g L^?1 (deprivation) or 30 g L^?1 (supplementation) sugar on morphological traits, photosynthetic attributes and intrinsic elements of the CAM pathway using the CAM orchid Phalaenopsis ‘Amaglade’. The growth of shoot (retarded) and root (induced) was differently affected by CO₂ enrichment and mixotrophic regime (+sugar). The Fv/Fm ratio was 14% more in CO₂-enriched treatment than at ambient level during in vitro growth. At elevated level of CO₂ and sugar treatment, the content of Chl(a + b), Chl a/b and Chl/Car was enhanced while carotenoid content remained unaltered. During in vitro growth, gas-exchange analysis indicated that increased uptake of CO₂ accorded with the increased rate of transpiration and unchanged stomatal conductance at elevated level of CO₂ under both photo- and mixotrophic growth condition. At elevated level of CO₂ and sugar deprivation, activities of Rubisco (26.4%) and PEPC (74.5%) was up-regulated. Among metabolites, the content of sucrose and starch was always higher under CO₂ enrichment during both in vitro and ex vitro growth. Our results indicate that plantlets grown under CO₂ enrichment developed completely viable photosynthetic apparatus ready to be efficiently transferred to ex vitro condition that has far-reaching implications in micropropagation of Phalaenopsis.     

Influence of environmental related concentrations of heavy metals on motility parameters and antioxidant responses in sturgeon sperm

The effects of heavy metals (Cd, Cr and Cd + Cr) on the motility parameters and oxidative stress of sterlet (Acipenser ruthenus) sperm were investigated in vitro. Sturgeon sperm were exposed for 2 h to heavy metals at environmental related concentrations (0.1 mg L^?1 Cr, 0.001 mg L^?1 Cd, 0.1 mg L^?1 Cr + 0.001 mg L^?1 Cd) and higher concentrations (5.0 mg L^?1 Cr, 0.05 mg L^?1 Cd, 5.0 mg L^?1 Cr + 0.05 mg L^?1 Cd). Results revealed that environmental concentrations of heavy metals had no significant influence on motility parameters and antioxidant responses indices in sturgeon sperm, except for LPO level and SOD activity. But higher concentrations of these metals induced oxidative tress in sturgeon sperm in vitro, associated with sperm motility parameters inhibition. Our results suggest that using of sperm in vitro assays may provide a novel and efficiently means for evaluating the effects of residual heavy metals in aquatic environment on sturgeon.