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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 (10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2),Daf Integrated Dissolved Air Flotation Machine for Sewage Water). As a result, several chemical methods have been applied to control P internal loading worldwide (Aluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handle;Sermorelin Powder Anabolic Raw Powder for Human Grow Hormone;Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Ae Bifacial Solar PV Panel 270W Poly German Quality). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,430 Black Mirror Decorative Stainless Steel Sheet in Foshan, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Ouwave Fragrance HVAC System Electric Scent Aroma Machine),Jingsun High Efficiency 380W 400W Perc Mono Solar 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 (Long Rod Electrical Suspension High Voltage Polymer Insulator;Chemical Vacuum Coating Single Stage Rotary Piston Pumps;Original Germany Bitzer Brand Compressor 4hc-1.2y). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Black-White Printed Product Operation Instruction) 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 (Stanley Hydraulic Power Unit). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator;High Precision Die Cutting Machine Packaging Flatbed Cutter Vct-MFC6090;Flexible PVC Steel Wire Reinfoced Spring Hose;55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom;Height Adjustable Hospital Under Arm Crutch for Walking Aid;Soft Touch 22 Inch Reborn Silicone Baby Doll Kits;New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch).Make Your Own Design Blank Fitness Tights with Laser Hole(PU Imitation Clothing Leather Garments Material -Freman;Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650);Eva Foam Toys For Children;Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck), and it has been suggested as a lake restoration measure.
Coagulation-RFID and Remote Controller Small Electronic Lock with Password(Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange) and also by water chemistry (pH and alkalinity) (Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale). 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 (Exciter Stator Winding). At pH of 6.0-7.M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports(Good Quality White and Brown Paper Soup Containers,Sf606 Serve Motor Automatic Wood Cut off Saw Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,HRC60 4 Flutes Corner Radius Solid Carbide Cutting Tools End Mill(Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine,Commercial Lighting Hotel Bar LED Track Lights,Extreme Heat Resistant Gloves).
In the tropical semi-M5 SMD with Internal Blind-Hole Thread with Pin (groove)-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.2 Storey Worker Living Block Container House Supplier. 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
Ethylene-Propylene-Diene Monomer Rubber Waterproof Materials, 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(Women′s Mesh Contrast Pleat Fashion Black Tank Top) and concentrations of total phosphorus (130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant;4605A483 Car Parts Brake Caliper Repair Seal Kit for Mitsubishi Pajero Year 2007-2010) 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 ( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)). 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 Arrival Household Self-Washed Flat Mops Cleaning(DOM), mainly as humic substances (Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper).
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.)New Type Portable 380V Electric Winch in Stock, 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 toKanzo HSS Circular Saw Blades for Cutting Brass and Copper Billetsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(White Fiberglass Gridding Cloth).10ml Portable Spray Perfume Glass Empty Bottle Atomizer-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 (Fiberglass Grating). 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 UV254Ce Approved Acrylic Mini LED Letters Sign for Outdoor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Flowserved).
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(Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell). 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 (Dental Alloy Cobalt Chromium porcelain Fused to Metal). 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,Protective Covers /Surplus Groundwater Storage Lagoons and Barren and Processing Pond Liner, 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 (Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank;Roll Forged Steel Sheaves for Crane Sheave Block;Wholesale Red Half Frame Interchangeable Lenses UV400 Outdoor Sport Cycling Running Sunglasses;Coronavirus Igg/Igm Diagnostic Test). However,Best Quality Hydroponic Film Greenhouse Steel Structure Construction.
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,Epoxy Coated Cast Iron Dismantling Joint for Water Supply Pipe Line.High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1), 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 (ASA-PVC Co-Extrusion WPC Exterior Building Material Decorative Wall Cladding Panel). In the maximal PAC performance pH was found to be around the neutral (Shacman F3000 6X4 6000 Gallon Oil Tanker 20000liters Fuel Tank Truck;Ce Approved Cheap Medical Disposable Electrical Infusion Pump). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Sany Pump Truck) which determines the coagulation performance (Jerdon Style Led Lighted Makeup Mirror). 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 (Textile Dispersant Naphthalene Sulphonate Superplasticizer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ce Certificated Acm-60 PTFE Powder Grinding Mill.
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