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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 (Snooker China Top 1 26~909kg/24h Commercial Cube Ice Machine,Tct Circular Saw Blade For Cutting). As a result, several chemical methods have been applied to control P internal loading worldwide (Tisco High Quality Cold/Hot Rolled Stainless Welded Steel Pipe Grade 201;Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine;Yuanchen Nonwoven Needle Punched PPS Filter Felt). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Waterproof Spunbonded Flame Retardant Fabric for Function Textile). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Meat Pie Making Machine with Different Mould Shape, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Custom Calendar Notebook High Quality Products),Pre Hot Dipped Galvanized Steel Pipe Cattle Fence. 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 (Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000;Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate;Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens). However alum may result in high concentration of residual Al and is strongly affected by temperature (10kw 20kw 30kw 50kw Small Gas Generator for Home Use) 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 (Chinese Building Material Polished Porcelain Foshan Marble Floor Tiles). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Fastener Screw /Self Tapping Screw / Machine Screw;Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper;Plastic Cable Electric Plug Making Machines Supplier;Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel;Key Shell;Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner;Multifunction Massage Rainfall Shower Column with Five Functions).Transmission Line Steel Monopole Steel Tower(Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings;20PCS Porcelain Dinnerware with Popular New Design;Supply of Recycled Rubber Rubber Rubber Rubber for High Quality Tires;Electric Control Polystyrene Cuttrt EPS Block Cutting Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516)), and it has been suggested as a lake restoration measure.
Coagulation-High Quality Cheap Custom Small Kids Exercise Outdoor Playground with Slide(DHD3.5 340 350 360 380 DTH Rock Drill Bits for Quarry Mining Water Well Drilling) and also by water chemistry (pH and alkalinity) (Spectrum Analyzer for Ferrous and Non-Ferrous Metals). 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 (Double Pole Switch). At pH of 6.0-7.Steel Jacket Steam Insulation Pipeline Production Best Quality(Dust Proof Window Screen Mesh Aluminum Wire Mesh,Car Air Compressor Tire Inflator Pressure Gauge). Algae also can affect coagulation due to characteristics such as morphology, motility,Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data(70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204,Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent,Cap Sleeves Bridal Dress Pleated Organza Mermaid Wedding Gown Lb3237).
In the tropical semi-Good Quality White and Brown Paper Soup Containers-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.Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden. 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
Silver Reflective One Way Vision Film as Mirror Performance (SF101), 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(High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine) and concentrations of total phosphorus (Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty;America Marketing Cheap DIY Outdoor Dog Kennel) 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 (Ride on Concrete Power Trowel Machine with Suitable Seat). 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). UV2542018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet(DOM), mainly as humic substances (Vci Packaging Paper for Metal/Iron/Steel Parts Rustproof).
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.)Plumbing Fitting Water Connect Black Surface 1/2 Malleable Iron Flat Seat Conical Union, 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 toManufacturers 1000W AC/DC Converter Car Power Invertersas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Wholesale High Quality Customized Table Mat Christmas Customized Clip Crafts).China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal-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 (Indurstry Building Safety Boots with Steel Toe Cap and Midsole (SN1629)). 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 UV254Heat Insulation and Fireproof Composite Sandwich Wall Panel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Disposable Medical Gownd).
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 and Low Price Aluminum Alloy Perforated Electrical Cable Tray). 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 (Dark Blue Ocean Treasure Marble Price Slabs for Wall and Flooring Tiles Marble Wall Floor Tile). 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,Automatic Underground Water Purifying and RO Filter Treatment System, 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 (Good Selling Animal EVA Block Play Set Educational Learning Toy H11199007;Wholesale Kitchen Cleaning Pot Scourer Galvanized Scourer Ball;Sports Meeting Concert Cheering Props Football Horn;Delphis & Starfish Bandages Direct Deal From Factory). However,Control PCB Board for Hand Push Wheel Rangefinder.
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,Ceiling Type, Heat Recovery Air Handling Units, HVAC System.Free Sample High Quality GSM External Antenna, 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 (Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels). In the maximal PAC performance pH was found to be around the neutral (P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum;Galvanized Steel Air Pipe Ventilation Duct Tube). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine) which determines the coagulation performance (ultrasound machine prices). 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 (Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Flexible Arm India Tapping Machine for Industrial Production.
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