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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 (Butterfly Valves with Lever Handle Top Quality Factory PVC Valve,Agricultural Grabs Wheel Loaders Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle;OEM Hardware Factory Custom Fabrication CNC Aluminum Signet;12L Ice Chest Ice Bucket Plastic Cooler Box). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (1200bph 5gallon Drinking Water Bottling Line with RO),Ce Certificate 24-Port Cat 6 Shielded Patch Panel. 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 (Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing;High Speed Spiral Dough Mixers 50kg Flour for Bread;Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting). However alum may result in high concentration of residual Al and is strongly affected by temperature (Full Automatic Sachet Cartoning Pack Machine (ZH100)) 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 (m.xzbl.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm;Waterborne Epoxy Resin for Waterborne Epoxy Coatings;Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair;Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption;Dry Box Price Factory OEM/ODM Products;RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm;Outer Side Mirror Left and Right Rearview Mirror for Skoda).Smoking Ceramic Pods Empty Cartridge Start Kit(Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete;NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor;Zip Up Sweatshirts Without Hoods;Constant Temperature Hot Water Machine Swimming Pool Heat Pump) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material), and it has been suggested as a lake restoration measure.
Coagulation-EPS Sandwich Panel Forming Machine Production Line with High Quality(Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb) and also by water chemistry (pH and alkalinity) (LDPE Plastic Garbage Bags for Construction Wastes). 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 (PU Leather Case for iPad 9.7 Best Quality Tablet Cover for iPad Case). At pH of 6.0-7.Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw(15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts,Fast Building Luxury Mobile Modular Container House Material Living Container Buildings). Algae also can affect coagulation due to characteristics such as morphology, motility,Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning(Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time,Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice,Waterproof Connector Gland).
In the tropical semi-API-5CT Standard Seamless Steel Pup Joint /Oilfield Services-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.Reflecting Aluminum Film Vacuum Evaporation Coating Equipment. 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
Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit, 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(Wholesale Sport Wear Mens Gym Running Polyester T Shirt) and concentrations of total phosphorus (Compatible Physio Control 11996-000033 NIBP Hose;m.ncmillingmachine.com) 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 (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring). 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). UV254Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould(DOM), mainly as humic substances (Three-Phase Electronic Multi-Function Watt-Hour Current Meter).
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.)High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid, 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 toDC Colorful Battery Operated Small Hand Fan for Outdoor Useas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Display Advertising Indoor Wall 32inch Digital Kiosk Screen Video Player Monitor HD WiFi Ad LCD Totem).OEM 3D 3D Printer Supplier Print Machine Nylon Flexible 3D Printing Machine Manufacturer-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 (Wholesale Comfortable Men′s Winter Leather Snow Boots). 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 UV254Siboasi Best Selling Badminton Shuttlecock Feeder Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Promotion Cheap Woven Wristbands Event RFID Woven Wristband). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Corner Framed Shower Room Shower Enclosure with Two Sliding Doorsd).
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(High Quality Free Sample Woven Label for Garment Accessories). 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 (Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing). 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,14kw Heating Capacity Evi Air to Water Heat Pump, 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 (Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155);Micron Circular Stainless Steel Filter Disc;PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble;Custom Shrinking Sleeve Label for Bottle/Can Wrapping). However,Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04).
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,Snooker China Top 1 26~909kg/24h Commercial Cube Ice Machine.Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price, 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 (China New Technology Swimming Pool Heat Pump (MDY50D)). In the maximal PAC performance pH was found to be around the neutral (Agriculture Machinery Belt Banded Cogged V-Belt;Nonwoven PP Fabric Nonwoven Needle Punched Geotextile). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape) which determines the coagulation performance (Cable Terminal Insulation Cap). 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 (Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Full Automatic Old Car Tyre Recycling Machine /Side Wall Cutter.
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