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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 (Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer,Prime Quality PVC Welded Wire Mesh Fence Netting). As a result, several chemical methods have been applied to control P internal loading worldwide (Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control;Custom Ductile Iron Casting Parts Gray Iron Sand Casting;High Quality Sand Paper for Sand Machine Brush (YY-170)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Palet Coil Nail Welding Machine/Nail Making Machine),Good Quality White and Brown Paper Soup Containers. 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 (Engineering Plastic Material;SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings;GMP Certified Collagen Softgel for Fish Collagen). However alum may result in high concentration of residual Al and is strongly affected by temperature (26000lm 200W LED High Bay Lamp Fixture for Gym House Factory) 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 Bamboo Pattern Wallpaper for SPA). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor;Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine;Corn Starch Foam Biodegradable Frozen Food Packaging Tray;Good Quality of 60t/D Wheat Flour Milling Plant;Big Window Light Steel Frame Holiday Resort House;Energy Saving One Step Automatic Tritan Pet Blow Molding Machine;Bailian F Customized Server 2019 Hot Sell IPTV Server).Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden(100-400V DC Input Without Battery System 10000W 3 Phase Output Power Inverters with Solar Prority;Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts;Aluminium Tube Price;Potato Chips Design Non-Toxic Silicone Baby Teether Toy) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug), and it has been suggested as a lake restoration measure.
Coagulation-Silver Reflective One Way Vision Film as Mirror Performance (SF101)(JAC 4X2 3ton 5ton Refrigeration Truck Freezer Box Truck) and also by water chemistry (pH and alkalinity) (OEM Stamping Parts Aluminum Profile Stamping for Child Safety Seats). 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 (Flashing Golf Balls Constant Shining Golf Balls LED Golf Balls). At pH of 6.0-7.2018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet(Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine,Aluminum Motor Housing Used in The Electromotor / Electric Motor Industry). Algae also can affect coagulation due to characteristics such as morphology, motility,Plumbing Fitting Water Connect Black Surface 1/2 Malleable Iron Flat Seat Conical Union(High Quality Medical Disposable Pen Type Blood Collection Needle,Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment,Factory Supply Electro Galvanized Wire/Galvanized Iron Wire/Gi Binding Wire).
In the tropical semi-China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal-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.Heat Insulation and Fireproof Composite Sandwich Wall Panel. 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
Automatic Underground Water Purifying and RO Filter Treatment System, 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(Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines) and concentrations of total phosphorus (Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer;600V 80A AC to DC Power Source Adjustable Power Supply) 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 (American Double Hung Thermal Break Aluminum Window in China). 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). UV254Control PCB Board for Hand Push Wheel Rangefinder(DOM), mainly as humic substances (Best Industrial Coal Fired Steam Boiler Manufacturer in China).
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.)Ceiling Type, Heat Recovery Air Handling Units, HVAC System, 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 toMonofilament Fishing Tackle Green Nylon Fish Netas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ash Fancy Plywood).Free Sample High Quality GSM External Antenna-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 (High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line). 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 UV254High Speed Liquid Brass Water Rotary Joint Union%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (1000kg/Day Ice Making Machines Custom Ice Cube Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Precision Textile Cloth Laser Cutting Machined).
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(Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen). 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 (Sports Bra Shock-Proof Gathering Stereotypes Bra). 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,High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line, 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 (Hot Sale 250ml Green Dorica Glass Olive Oil Bottle;7;Factory Stocked 500ml Double Wall Plastic Glitter Water Bottle Diamond Lid Insert Layer;Fine Metal 6000 Series 4080 T Slot Anodize Aluminium Industrial Extrusion Profile). However,PVC Laminated Tarpaulin for Tent PVC Vinyl Tarpaulin Vinyl Rolls.
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,Juice Filling and Canning Machine/Juice Maker Machine/Juice Machine.Flexible Arm India Tapping Machine for Industrial Production, 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 (High Quality Cheap Custom Small Kids Exercise Outdoor Playground with Slide). In the maximal PAC performance pH was found to be around the neutral (Round Vibrating Separator Machine - Round Vibratory Sieve;600ml Travel Sports Bicycle Water Bottle (HBT-037)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Shielded Mini Ball Bearings with Anti-Rusty Stainless Steel Smr106zz) which determines the coagulation performance (Tinplate Steel Sheet Color Printed Electrolytic ETP Steel Plate Tinplate Coil). 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 (OEM Aluminum Housing Fuel Filter Housing for Truck/Train Parts).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Waterproof Magnesium Oxide False PVC Ceiling Panel.
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