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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Fashion Design Steel-Wood Large Conference Table,Kokubun Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet;Easy to Use Mobile Filter Unit for Light to Medium Welding;8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Dry Ice Production Block Cube Maker Producer Refrigeration Industry Use Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Personalized Custom PVC USB Flash Drive for Company Promotional Gift, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ul2464 Shielded Electrical Cable),Automatic Column and Boom Welding Manipulator Dlh. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock;Topkit Tower Crane Rct6011-6 for Construction Building;Motion Sensor Light Stick Closet Light Wall LED Night Light). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Stainless Steel Clamp Sanitary Ball Check Butterfly Valve) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Waterproof and Moldproof Marble Floor Grouting). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2-7dBi GPS/GSM SMA RF Coaxial High Gain WiFi Antenna;P810 Indoor & Outdoor Single Color Vehicle LED Display Module;Wholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dog;6 Cups Continous Barbeque Sauce Chili Paste Ketchup Cup Filling and Sealing Machine;Kids Surf Bodyboard;Aluminum Mold Making Die Casting Motorcycle Spare Parts;Plastic PVC/WPC Granulator Die Face Cutter Extruder Machine).3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material(Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose;Stage LED Bar 54PCS*3W RGBW DJ Disco Stage Lights;China Kids Hospital Mask;Fat Tire City Coco Electric Bicycle Motorcycl Bike Electric Scooter for Adult) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring), and it has been suggested as a lake restoration measure.
Coagulation-Auto Parts for Plastic Products Injection Mould Mold Tooling(CNC Machining Milling Aluminum Bike Components) and also by water chemistry (pH and alkalinity) (Dny Automatic Stainless Steel 304 Belt Filter Press). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (barrels cooler). At pH of 6.0-7.2019 Smile Rabbit LED Silicone Night Light 7 Colors Desk Table Lamp For Kids(Hot Sale Bamboo Toothbrush in Flate Simple Design,Honed St52 Piston Tube for Hydrau; IC Cylinder). Algae also can affect coagulation due to characteristics such as morphology, motility,Automotive Aluminum Engine Parts Low Pressure Casting(EV850m CNC Machine High Precision Vertical Machining Centers Price,Stainless Steel Welded Wire Mesh BBQ Grill Grate/Mesh for Cooking,Latest Products 2018 Baby Girl Shoes Kids Bowknot Cheap Childrens Shoe Shiny).
In the tropical semi-Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Public Address System High Power Range Outdoor Column Speaker, FCL-440. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Yg15/Yg8 Mirror Polished Hip Sintered Tungsten Carbide Wire Guide Rollers) and concentrations of total phosphorus ( Cosmetic Fluorescent Pigment Powder Manufacturer;Complex Injection Molds Manufacturers Cheap Price) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254New Product 2019 Milky White Electrochromic Smart Film(DOM), mainly as humic substances (DIN976 Grade 4.8 8.8 10.9 12.9 Carbon Steel Zinc Plated HDG Threaded Rods Bar).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according to1325 High Quality Steel Aluminum Metal Plasma Cutting Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Metal Logo Die Cutting Nameplate with Adhesive Labels).Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047)-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Thin Wall 7049 7050 Aluminum Tube with PVC Package). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Concrete Floor Grinding Disc Machine for Four Segmentsd).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Transparent High Quality Building Glass Curtain Wall From China Suppliers). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Flat Compression Injection Mould Die Spring/Standard Coil Spring with Rectangular Section). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (ACP/ACP Sheet/Aluminum Composite Panel Manufacturer;Yellow Corrugated PE-Al-PE Gas Pipe with Size 16mm to 32mm;New Business Projects Mobile 5D Cinema with High Quality;High Pressure Multi-Cartridge Stainless Steel Water Treatment Filter Housing). However,Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Living Room Furniture TV Stand Electric Fireplace with No Heating.High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (5 Inch Diamond Protected Teeth Blades for Cutting Granite). In the maximal PAC performance pH was found to be around the neutral (Custom Your Design Logo Women T Shirt Fashion Cotton Casual Girl Tshirt Basic Ladies T-Shirt;Steel Structure Roofs System TPO Waterproof Membranes). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Water Heater Single Head Shrinking Machine) which determines the coagulation performance (www.checkingfixturebr.com). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Co-Extrusion Extruder Single Screw Auxiliary).
15 Inch IP65 Waterproof Industrial Touch Screen Monitor, charge and density, factors that influence directly in flock sedimentation.Steel Warehouse Metallic Curved Roof Design Structure(2019 Unique Design UV Printing Phone Case for Apple iPhone 8;Immersion Gold 94V0 Circuit Board Assembly Saving Energy Electrical PCB). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker). Extracellular and surface-High Precision Customized Medical Injection Mold for Needle Holder(OEM Warp Knitting Souvenir Advertising Ball Games Sports Fan Custom Sports Scarf,OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Sun Cover Heat Resistance Shade Privacy Screen), which can be one important cause of the increase in coagulant demand in algae-rich waters (Clear Plastic PVC Window Cmky Full Color Printing Box).Remote Lighting Controls Outside Lights Controller LC-6p13(Good Quality Brow Pencil Pencil Private Label Wholesale), particularly humic susbtances. Humic substances are highly negatively charged (Malleable Casting Iron Pipe Fitting Tee by Sand Cast), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic). Maximal UV254removal was observed to be found around pH 6.0 (Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Jingsun off Grid 100kw Solar Power System for Project).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits.
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