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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 (12mm Thickness Square Corrugated Cake Board,Polycarboxylate Ether/Aging Concrete Water Reducer PCE). As a result, several chemical methods have been applied to control P internal loading worldwide (Customized EPDM NBR Rubber Bellows Expansion Joint;Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting;Non-Slip Baby Kids Fashion PVC Rain Boots). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Axial Flow Clean Water Submersible Sump Irrigation Pump). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Aluminum Mold Making Die Casting Motorcycle Spare Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ground Engineering Processing Concrete Floor Grinder),Metal Hardware CNC Turning, Milling, Aluminum Parts, Metal Parts, Tool Parts, Mechanical Parts. 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 (Air Bubble Stone as Ozone Diffuser for Air Pump;2019 New Fashion Silicone Hot-Water Bag for Girl;Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables). However alum may result in high concentration of residual Al and is strongly affected by temperature (Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer) 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 (Computerized Socks Knitting Machine Plain Socks Machine Terry Socks Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse;OEM CNC Machine Machining Textile Machine Accessories;Simple 3 Fold Orthopedic Folding Foam Mattress;Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer;433mhz Omni Directional Antenna;Factory Price Resin Wedding Chairs for Sale;Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm).Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper(Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic;Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light;Estate Planning For China Assets;20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Round Pipe Welded Pipe Middle Size for Chemical Companies), and it has been suggested as a lake restoration measure.
Coagulation-5kg Pleasant Scent Brilliant Fasclean Extra Top Laundry Detergent(Quality Medium Stapler with Staples Remover) and also by water chemistry (pH and alkalinity) (G02f12L Tempered Glass Shower Cabin). 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 (Sawey Nozzle 1.5mm New Wa-200 Automatic Big Spray Gun). At pH of 6.0-7.Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery(Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel,Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension). Algae also can affect coagulation due to characteristics such as morphology, motility,Metal Enclosure Withdrawable Distribution Switchgear Cabinet Low Voltage( 7050,115cm Mini Sex Doll for Man Big Breast Love Doll,Efficient Vacuum Road Sweeper Truck).
In the tropical semi-PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer-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.Permanent N50 Tiny Mini Neodymium Magnet for Sale. 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
Stainless Steel Waterproof Anti-Explosion Ik10 IP65 LED Linear Tube Light, 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(Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs) and concentrations of total phosphorus (Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment;Swivel Executive Staff Visitor Office Plastic Mesh Fabric Chair Ow-W868) 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 (Long Span Galvanized Light Weight Steel Structure). 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). UV254Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop(DOM), mainly as humic substances (China Gingseng Extract Ginsenosides 15% 20% 80%).
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.)Butterfly Valves with Lever Handle Top Quality Factory PVC Valve, 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 toHandrail Fitting / Stainless Steel Round & Square Tube Connectoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ocean Free design Ball Pool Small Trampoline Indoor Playgorund).Made in China High Quality Ceramic Fiber Packing Seal Ring-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 (FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body). 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 UV254Hydraulic Small Boat Marine Deck Crane for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (ECG Shell Molding Custom Plastic Mould Two-Color Mouldd).
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(Wholesale Portable Travel Bamboo Tooth Brush Holder). 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 (Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe). 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 Quality Meat Pie Making Machine with Different Mould Shape, 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 (Automatic Non-Woven T-Shirt Bag Making Machine with High Efficient;Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5); Non-Contact Thermometer Gt750;Sintered Metal Filters). However,Pre Hot Dipped Galvanized Steel Pipe Cattle Fence.
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,Transmission Line Steel Monopole Steel Tower.High Quality Cheap Custom Small Kids Exercise Outdoor Playground with Slide, 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 (Personal Skin Care Silicone Sonic Facial Cleansing Brush). In the maximal PAC performance pH was found to be around the neutral (UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine;Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools) which determines the coagulation performance (Safety Control Solenoid Brass Material Gas Magnet Valve). 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 (ASTM A53 Black Round Metal Carbon ERW Steel Pipe).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Silver Reflective One Way Vision Film as Mirror Performance (SF101).
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