Removing nitrogen and phosphorus from simulated wastewater using algal biofilm technique

Algal biofilmtechnology is a new and advanced wastewater treatment method. Experimental study on removing nitrogen and phosphorus from simulated wastewater using algal biofilm under the continuous light of 3500 Lux in the batch and continuous systems was carried out in this paper to assess the performance of algal biofilm in removing nutrients. The results showed that the effect of removing nitrogen and phosphorus by algal biofilm was remarkable in the batch system. The removal efficiencies of total phosphorus (TP), total nitrogen (TN), ammonia-nitrogen (NH₃-N), and chemical oxygen demand (COD) reached 98.17%, 86.58%, 91.88%, and 97.11%, respectively. In the continuous system, hydraulic retention time (HRT) of 4 days was adopted; the effects of removing TP, TN, NH₃-N, and COD by algal biofilm were very stable. During a run of 24 days, the removal efficiencies of TP, TN, NH₃-N, and COD reached 95.38%, 83.93%, 82.38%, and 92.31%, respectively. This study demonstrates the feasibility of removing nitrogen and phosphorus from simulated wastewater using algal biofilm.     

Seasonal differences in treatment efficiency of a set of stabilization ponds in a semi-arid region

This article aims to determine the significant differences of the seasonal changes of pH, chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solids (TSS) parameters in a wastewater stabilization pond. The variation of these parameters followed the seasonal pattern of temperature. The mean seasonal pH of the influent wastewater ranged between 7.8 (in spring) and 7.9 (in summer), while in the final effluents it was between 7.9 (in winter) and 8.3 (in summer). The mean seasonal COD of the influent wastewater ranged between 650?mg?L^?1 in spring and 600?mg?L^?1 in autumn, whereas in the effluents it was between 150?mg?L^?1 in autumn and 270?mg?L^?1 in spring. The mean seasonal BOD₅ of the influent wastewater ranged between 360?mg?L^?1 in autumn and 390?mg?L^?1 in winter, whereas in the effluents it was between 66?mg?L^?1 in summer and 130?mg?L^?1 in winter. The results showed that the percent removals of COD, BOD₅ and TSS from final effluents were maximum in summer for COD and BOD₅ (76%), summer (83%) and for TSS in winter (78%), respectively. Data analysis showed that there were significant differences between parameters of pH, COD, BOD₅ and TSS at four different seasons (p?相似文献   

Fe-pillared bentonite,a stable Fenton catalyst for treatment of petroleum refinery wastewater

Fe-pillared bentonite (Fe-Bent) was prepared by ion exchange as heterogeneous catalyst for degradation of organic contaminants in petroleum refinery wastewater. X-ray diffraction analysis showed the existence of α-Fe₂O₃. The effects of pH, H₂O₂ concentration, and catalyst dosage on the rate of lowering the chemical oxygen demand (COD) were investigated in detail. Removal efficiency of COD can be up to 92% under the following conditions: dosage of Fe-Bent 7 g L^?1, pH value 3, and H₂O₂ concentration 10 mmol L^?1. Fe-Bent showed good stability for the degradation of organics in petroleum refinery wastewater for five cycles. The adsorption of organics in wastewater onto Fe-Bent could be well described by a pseudo-second-order kinetic model.     

Kinetics of acetyl CoA: Arylamine N‐acetyltransferase from rapid and slow acetylator fish tissues

N‐acetyltransferase (NAT) activity was determined in 100 fish (Oreochromis mossambicus) livers using 2‐aminofluorene and p‐aminobenzoic acid as substrates. Overall, the liver NAT activity of the 50 females was higher than the liver NAT activity of the 50 males. The activities (mean ± SD) of NAT from kidney, blood, intestine, and liver of males was 0.42 ± 0.11, 0.12 ± 0.03, 0.12 ± 0.08, and 1.56 ± 0.54 nmol/min/mg protein for the acetylation of 2‐aminofluorene and 0.36 ± 0.09, 0.09 ± 0.01, 0.11 ± 0.04, and 0.46 ± 0.15 nmol/min/mg protein for the acetylation of p‐aminobenzoic acid. In kidney, blood, intestine, and liver from female fish, the activities obtained were 1.60 ± 0.12, 0.35 ± 0.07, 0.15 ± 0.09, and 1.89 ± 0.50 nmol/min/mg protein for 2‐aminofluorene and 0.95 ± 0.11, 0.27 ± 0.03, 0.13 ± 0.09, and 0.57 ± 0.12nmol/min/mg protein for p‐aminobenzoic acid. Kinetic constants for arylamine N‐acetyltransferase activity in kidney, blood, intestine, and liver from fish with rapid, intermediate, and slow acetylator activity were determined. Apparent K _m and V _max values for 2‐aminofluorene were 5.5 and 7‐fold higher for liver than for the other tissues. Apparent K _m and V _max values for p‐aminobenzoic acid were 3.5 and 4.7‐fold higher for liver than for the other tissues. Based on the 2‐aminofluorene NAT activity of liver, there appears to be a polymorphism in NAT activity with 16 rapid, 28 intermediate, and 56 slow acetylators among the 100 fish assayed. This is the first demonstration of acetyl CoA: arylamine N‐acetyltransferase activity in fresh water fish and could lead to the development of a fish model for monitoring the effect of pollution of water environments on native species.     

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N₂O) emissions, together with the relationships between N₂O and water quality parameters in free water surface constructed wetlands, were investigated with laboratoryscale systems. N₂O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N₂O emission in the system with middle COD influent concentration was the least. The relationships between N₂O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N₂O flux. The multiple linear regression model against principal components indicated that different water parameters affected N₂O flux with different COD concentrations in the influent, but nitrate nitrogen affected N₂O flux in all systems.     

Paeonol promotes arylamine N‐acetyltransferase activity in human bladder tumor cells

Paeonol was used to determine effects of arylamine N‐acetyltransferase (NAT) activity in human bladder tumor cells. The NAT activity was measured by high performance liquid chromatography assaying for the amounts of N‐acetyl‐2‐aminofluorene (2‐AAF) and N‐acetyl‐p‐amino‐benzoic acid (N‐Ac‐PABA) and remaining 2‐aminofluorene (2‐AF) and p‐aminobenzoic acid (PABA). The NAT activity in human bladder tumor cells was promoted by paeonol in a dose‐dependent manner, i.e. the higher the concentration of paeonol, the higher the promotion of NAT activity. The data also indicated that paeonol increases the apparent values of K_m and K_max from human bladder tumor cells in cytosols and intact cells. This report is the first demonstration to show paeonol did promote human bladder tumor cell NAT activity.     

Classification of contaminants and treatability evaluation of domestic wastewater

Long-term sampling and analysis were conducted in a domestic wastewater treatment plant for the investigation on the characteristics of the representative contaminants in raw sewage such as SS, COD, BOD₅, TP, and TN. All these constituents were classified into dissolved and suspended groups by using a 0.45-μm membrane filter, and the concentration of each constituent in each group was analyzed. As a result, almost 100% of the SS was found to be suspended matter, as well as about 65% of COD, 60% of BOD₅, 50% of P, and 20% of N. All these could be easily removed by sedimentation or coagulation/sedimentation. A treatability evaluation diagram was proposed for a rational selection of wastewater treatment process in accordance with raw water quality.     

Treatment of biologically treated effluents from baker's yeast industry by membrane and ozone technologies

This paper presents pilot‐scale membrane treatment results performed on biologically treated effluents from fermentation industry and ozone oxidation on concentrates from the same membrane treatment system. The results obtained from the ultrafiltration (UF) and/or the reverse osmosis (RO) systems indicate that membrane treatment are very effective for COD, Color, NH₃‐N and conductivity removal. Ozone oxidation of the membrane concentrates was tested to increase biodegradability of the wastes. The initial ratios of Biochemical oxygen demand (BOD₅) to Chemical oxygen demand (COD) were increased significantly by applying chemicaloxidation with O₃ and O₃ + H₂O₂.     

Effects of ellagic acid on arylamine N‐acetyltransferase activity in human colon tumor cells

The inhibition of arylamine N‐acetyltransferase (NAT) activity by ellagic acid was determined in a human colon tumor (adenocarcinoma) cell line. Two assay systems were performed, one with cellular cytosols (9000g supernatant), the other with intact colon tumor cell suspensions. The NAT activity in a human colon tumor cell line was inhibited by ellagic acid in a dose‐dependent manner in both types of examined systems: i.e. the greater the concentration of ellagic acid in the reaction, the greater the inhibition of NAT activities in both systems. The data also indicated that ellagic acid decreased the apparent K _m and V _max of NAT enzymes from human colon tumor cells in both the systems examined. This report is the first demonstration which showed ellagic acid affect human colon tumor cell NAT activity.     

Effects of metal pollution in the monosodium glutamate production effluent on full exploitation and biological treatment

Monosodium glutamate (MSG) effluent was sampled from three MSG mills and 21 metal elements were measured with a inductively coupled plasma (ICP) Spectrometer. The total metal concentration of each MSG wastewater sample was 19192, 3190 and 3161 mg/L respectively. Compared with the water quality standard issued by the Chinese Government and the World Health Organization (WHO), some values were found to exceed the standards. The 24hr‐LC₅₀, 48hr‐LC₅₀, 72hr‐LC₅₀ and 96hr‐LC₅₀ to the fish Ctenopharyngodon idellus were 6.9%, 3.2%, 2.5% and 1.4% MSG wastewater individually. The specific growth rate for photosynthetic bacteria (PSB) Rhodopseudomonas sphaeroides was inhibited by the metals in MSG wastewater. Therefor the MSG wastewater should not be discharged into drinking, irrigation and fishery water systems, moreover it cannot be treated by general biological processes efficiently. How to develop an effective biotechnique for the utilization of organic pollutants in MSG effluent will also be discussed in this paper.     

Systematic characterization and chemical treatment of olive oil mill wastewater

Classic and centrifugal olive oil mill wastewater volumes of 1.18 and 1.68m³/Mg olives and corresponding polluting loads of 37 and 53 Kg BOD₅ and 82 and 121 Kg COD/Mg olives were established in a systematic study of 15 mills. Lime treatment at an optimum pH level near 11 requiring a dose less than 10g/l effected COD removals from 15 to 22% for classic and from 33 to 46% for centrifugal mill waste. The volume of resulting sludge was large and could not be adequately handled by sedimentation; the sludge had good dewatering characteristics and was amenable to simple straining. Excess lime treatment using up to 50 g/l lime offered little additional benefit.     

不同微藻对典型行业废水急性毒性响应的敏感性研究

研究考察了不同行业废水对4种微藻24 h和72 h的急性毒性效应。以斜生栅藻(Scenedesmus obliquus)、蛋白核小球藻(Chlorella pyrenoidosa)、海水小球藻(Chlorella spp.)以及等鞭金藻(Isochrysis galbana)为指示生物,采用COD浓度较高的焦化厂实际生产废水和制药厂实际生产废水、COD浓度较低的印染厂生化处理后出水和城市污水处理厂进出水作为受试水体,以微藻的生长抑制率为测试指标,评价微藻对不同行业废水的急性毒性效应和敏感性。结果表明,不同行业废水对4种微藻的急性毒性效应有所不同:焦化废水对等鞭金藻的生长抑制作用最强,制药废水对斜生栅藻的毒性效应最为明显,印染废水及城市污水处理厂的进出水对海水小球藻的毒性较为显著,说明不同微藻对不同行业废水毒性的敏感性存在差异。上述研究结果为废水毒性评价中受试物种的选择提供了基础数据。     

Photocatalytic oxidation of the textile dye basic red 18 with irradiated titanium dioxide

One of the major problems of textile wastewater is the presence of dye materials, because colour is visible to the public even if the dye concentration is lower than other pollutants, and needs therefore to be removed from the wastewater before it is discharged. Techniques based on “advanced oxidative processes” such as photocatalysed oxidation seem to be very promising for industrial wastewater treatment, especially for decolourization of textile effluents. In this work, we describe the photocatalytic degradation of the textile dye Basic Red 18 (BR 18) in aqueous solution using two different types of TiO₂ as photocatalyst: Degussa P25 (80% anatase) and Framitalia (100% anatase). Photooxidation of BR 18 was followed by HPLC analysis, and kinetic parameters were evaluated in order to optimise the treatment procedure. The results obtained in this work showed that the colour became virtually zero and the chemical oxygen demand (COD) is strongly reduced at the end of the treatment. The obtained results are compared with the efficiency of decolourization using the H₂O₂/UV System. Finally, marine mussel test was used to evaluate the efficiency of photocatalytic oxidation with TiO₂ in terms of ecotoxicity. A significant reduction of cumulative mortality was observed for the treated effluent.     

Effect of short-term atrazine addition on the performance of an anaerobic/anoxic/oxic process

In this study, an anaerobic/anoxic/oxic (A²O) wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition. The results provided an evaluation on the effects of an accidental pollution on the operation of a wastewater treatment plant (WWTP) in relation to Chemical Oxygen Demand (COD) and biological nutrient removal. Domestic wastewater with atrazine addition in 3 continuous days was treated when steady biological nutrient removal was achieved in the A²O process. The concentrations of atrazine were 15, 10, and 5 mg·L^?1 on days 1, 2 and 3, respectively. The results showed that atrazine addition did not affect the removal of COD. The specific NH₄ ⁺ oxidation rate and NO₃ ^? reduction rate decreased slightly due to the short-term atrazine addition. However, it did not affect the nitrogen removal due to the high nitrification and denitrification capacity of the system. Total nitrogen (TN) removal was steady, and more than 70% was removed during the period studied. The phosphorus removal rate was not affected by the short-term addition of atrazine under the applied experimental conditions. However, more poly-hydroxy-alkanoate (PHA) was generated and utilized during atrazine addition. The results of the oxygen uptake rate (OUR) showed that the respiration of nitrifiers decreased significantly, while the activity of carbon utilizers had no obvious change with the atrazine addition. Atrazine was not removed with the A²O process, even via absorption by the activated sludge in the process of the short-term addition of atrazine.     

Organic matter balances in anaerobic digestors

Organic carbon and COD balances in a system of 12 anaerobic units operating at organic loading levels 0.4–0.8 kg COD/m³.d and hydraulic detention times 8–20 d resulted in a mean CH₄ production of 341 ml/g COD converted and a mean CH₄ + CO₂ production 1815 ml/g OC converted. The gas retained in the liquid anaerobic effluent was mainly carbon dioxide (94–98%).     

Comparative experiment on treating digested piggery wastewater with a biofilm MBR and conventional MBR: simultaneous removal of nitrogen and antibiotics

A biofilm membrane bioreactor (BF-MBR) and a conventional membrane bioreactor (MBR) were parallelly operated for treating digested piggery wastewater. The removal performance of COD, TN, NH₄ ⁺-N, TP as well as antibiotics were simultaneously studied when the hydraulic retention time (HRT) was gradually shortened from 9 d to 1 d and when the ratio of influent COD to TN was changed. The results showed that the effluent quality in both reactors was poor and unstable at an influent COD/TN ratio of 1.0±0.2. The effluent quality was significantly improved as the influent COD/TN ratio was increased to 2.3±0.5. The averaged removal rates of COD, NH₄ ⁺-N, TN and TP were 92.1%, 97.1%, 35.6% and 54.2%, respectively, in the BF-MBR, significantly higher than the corresponding values of 91.7%, 90.9%, 17.4% and 31.9% in the MBR. Analysis of 11 typical veterinary antibiotics (from the tetracycline, sulfonamide, quinolone, and macrolide families) revealed that the BF-MBR removed more antibiotics than the MBR. Although the antibiotics removal decreased with a shortened HRT, high antibiotics removals of 86.8%, 80.2% and 45.3% were observed in the BF-MBR at HRTof 5–4 d, 3–2 d and 1 d, respectively, while the corresponding values were only 83.8%, 57.0% and 25.5% in the MBR. Moreover, the BF-MBR showed a 15% higher retention rate of antibiotics and consumed 40% less alkalinity than the MBR. Results above suggest that the BF-MBR was more suitable for digested piggery wastewater treatment.

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Light‐induced changes in rabbit pineal gland n‐acetyltransferase activity

N‐acetyltransferase (NAT) activity was determined in different ages of New Zealand White rabbit pineal gland using 2‐aminofluorene and p‐aminobenzoic acid as substrates and it was assayed by high pressure liquid chromatography. Rabbits of different ages were either sacrificed during the light phase, exposed to darkness or light for 1 min during the dark phase of the lighting cycle, returned to their cages in darkness for 30 min and then sacrificed. Pineal gland NAT activity in animal nocturnally exposed to 1 min of light was inhibited in animals 1 ‐day‐old of age. Nocturnal light exposure did not inhibit enzyme activity in 1‐day‐old rabbit, even though these animal displayed clear light : dark differences in pineal gland NAT activity. Nocturnal light exposure also did not inhibit night time levels of NAT activity in 1‐day‐old animals who had been bilaterally enucleated. The result suggested that this effect is retinally mediated. Pre‐treatment of 1‐day‐old and 60‐day‐old animals with the isoproterenol (beta‐noradrenoreceptor agonist drug), prevented the nocturnal light‐induced inhibition of NAT activity. The different sensitivity of 60‐day‐old and 1‐day‐old animals to different illuminances or durations of nocturnal light exposure, was that the duration or intensity of light exposure was enable to inhibit nocturnal NAT activity. The NAT activity was at least 3.2‐ to 4.6‐fold greater in 1‐day‐old rabbits compared to 60‐day‐old rabbits. Kinetic constants for arylamine NAT activity in pineal gland from rabbits were determined. K_m and F_max values for 2‐aminofluorene were 2.6‐fold higher for light exposure than for no light exposure rabbits. This is the first demonstration of the retina‐pineal gland pathway appears light‐induced changes in pineal glands of animals in 1‐day‐old of ages or older; but this pathway does not function in 60‐day‐old rabbits like manner in 1‐day‐old rabbits.     

In vitro Methylation of Arsenite in Flemish giant rabbit Cytosol

The formation of ⁷⁴As‐monomethyIarsonic acid and ⁷⁴As‐dimethylarsinic acid from carrier‐free radiolabelled ⁷⁴As‐arsenite was evaluated in an assay mixture containing 17.6% liver cytosol from the Flemish Giant rabbit. The optimal incubation temperature and pH were respectively, 39°C and 7.6. After a 2h incubation about 90% of ⁷⁴As was protein bound. Protein bound ⁷⁴As was released by hot 2 M HNO₃ (1 min, 110°C). The treatment did not destroy methylated As‐species. Up to 70% of the carrier‐free ⁷⁴As‐arsenite was methylated. Liver cytosol was stored, without loss of activity, in liquid nitrogen in the presence of 2 mM glutathione. The optimal s‐adenosyl‐methionine concentration was 1.7mM. Formation of ⁷⁴As‐monomethylarsonic acid and ⁷⁴As‐dimethylarsinic acid increased up to a glutathione concentration of respectively 10 and 20 mM. Methylation also went through in the presence of other reducing agents and proved to be ATP dependent.     

Algal purification of pretreated landfill Leachate

The efficiency of microalgae in removing various pollutants in landfill leachate after pretreatment by free stripping or air stripping was tested by a laboratory batch system. The results showed that Chlorella pyrenoidosa and Scenedesmus sp. had similar removal efficiencies with regard to ammoniacal‐nitrogen, oxidized‐nitrogen, orthophosphate and chemical oxygen demand (COD). The COD removal by algal treatment was better in Junk Bay (JB) leachate than in Gin Drinkers’ Bay (GDB) leachate (14–21% and 0.4–7% respectively). No significant difference (P > 0.05) was found in removing other nutrients including ammoniacal‐nitrogen, oxidized‐nitrogen and orthophosphate between leachate from the two landfills, regardless of the pretreatment used. The removal efficiencies of ammoniacal‐nitrogen and phosphorus were found to be higher in air‐stripped leachate than in free‐stripped one. Removal of ammoniacal‐nitrogen and phosphorus in air‐stripped leachate was 30% and 87% respectively. Poor removal of ammoniacal‐nitrogen was probably due to a deficiency in phosphorus (high N : P ratio) for algal growth in leachate. The two‐stage leachate treatment (ammonia stripping followed by algal purification) resulted in overall reduction of COD (38–51%), ammoniacal‐nitrogen (72–96%) and orthophosphate (79–96%).