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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 (China Touch Screen for iPhone 6s LCD Touch Screen Digitizer,Crimping Terminal Lug). As a result, several chemical methods have been applied to control P internal loading worldwide (Srz Industrial Radiator;130kg/M3 Plastic PVC Core Foam for FRP Vacuum Infusion; Metal Duct Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Metallized Film for Laminating Color Printing Packaging Materials, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Knitted Cotton Hand Gloves),Automatic Plastic Pet Preform Injection Moulding Machine Price. 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 (Tungsten Carbide Milling Insert for Book Binding;PC Black Plastic Material Polycarbonate PC Granules Resin;3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration). However alum may result in high concentration of residual Al and is strongly affected by temperature (3m 1500 Electrical Pipe Wrap Tape Vinyl PVC Coated Wire Insulation Tape) 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 (Cloth Cutting Machine Blade). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte);Galvanised Iron Roofing Plate/Hot Dipped Galvanized Corrugated Roofing Sheet;Plastic Valve with The Membrane Heat Welding Machine;Front Lifting Used Tipper Second Hand Dumper Volvo Dump Truck Original From Sweden;Seamless Connection 0.6m 1.2m LED Linear Lighting;6 in 1 H2 O2 Hydra Facial Water Oxygen Dermabrasion Aqua Peel Skin Clean Machine;CCTV Security System Projects IP Camera Factory Hikvision IP Camera).275ml Ice Beer Cocktail Carbonated Drink Glass Bottle(Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption;High Quality Double Link Ra DVI D 24+1 Pin Connector;China Hot Sale Forged Steel Grinding Media Ball For Ball Mill;Electrical Insulation Flexible Crepe Paper Tube for Transformer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality Humidity Control Chamber Artificial Climate Chamber), and it has been suggested as a lake restoration measure.
Coagulation-Garde 4.8/8.8 DIN 603 Carriage Bolt/Mushroom Round Head Bolt(Best Quality Hydroponic Film Greenhouse Steel Structure Construction) and also by water chemistry (pH and alkalinity) (Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure). 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 (GU10 BS476 Tilt Fire Rated Downlight for GU10 LED Bulbs). At pH of 6.0-7.Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould(Potable Expansion Vessel Suitable for Sanitary Water Applications,IP65 Waterproof Exterior Hanging Batten Linear Lighting LED Tri-Proof Light). Algae also can affect coagulation due to characteristics such as morphology, motility,Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM(Transformer-Base Factory Equipment UPS 3 Three Phase in 3 Phase Output 60-400 kVA Online UPS,Forged Custom Exterior French Door Wrought Iron Double Entry Doors,Mg Die-Casting Part).
In the tropical semi-All-in-One Fool Metal Continuous Casting Machine/Complete CCM with Very Low Investment-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.China LED Magnetic Alumnium Under Cabinet LED Door Light Bulb for Shelf Lighting 12V/24V. 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
C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm, 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( 4 Butanediol Bdo CAS 110-63-4 with Lowest Price) and concentrations of total phosphorus (Marine Studless Link Anchor Chain for Sales;Alcohol Lamp) 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 (Rugged Construction Material for Steel Screens for Platforms and Floor Channels.). 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). UV254High Chrome Cast Iron Ball Forged Steel Ball Grinding Media(DOM), mainly as humic substances (Htzh-2h Portable Sf6 6-in-1 Gas Comprehensive Analyzer).
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.)Coolsour Air-Conditioning Compressor Crankcase Silicone Rubber Heating Strip, 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 to Dumper Truckas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Low Borosilicate Glass Bottle for Injection Use (30ml)).Wholesale Factory Price Cheap Arctic Cat ATV Parts Custom Size 4X4 ATV Tail Lights-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 (Shenzhen Manufactory Specilized in LED Light Manufacturing Line Setup). 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 UV254HPMC for White Cement Admixtures Putty Powder Additives%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Floating Oil Seal 150-27-00020 Excavator Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Acrylic Riser Staged).
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(Big Width Different Thickness Pet Release Film). 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 (Best Price China 1325 CNC Plasma Cutting Machine). 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,Garden Stone Table &Chair, Granite Outdoor Table, 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 (Natural Light Green/Beige/Pink Slate Thin Cut Surface Culture Stone;Digital Timer 15/30/60/90/120/180 Minutes Mechanical Timer for Oven/Stove;Trunking System Busbar Bus Duct 2000A Bus Way;European Style Full Function Baby Rocking Playpen Baby Crib with Colorful Design). However,Hot and Cold Temperature Thermal Shock Testing Equipment.
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,Hardware Tools 1.2mm Thickness Wire Pole Pipe Clip Tube Clamps.Water Centrifugal Pump for Swimming Pool Water Transfering, 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 (Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer). In the maximal PAC performance pH was found to be around the neutral (Flexible Arm India Tapping Machine for Industrial Production;Standard Vertical Rotary Automated Smart Tower Car Parking System). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5) which determines the coagulation performance (Square reed diffuser bottle 100ml 50ml 30ml 150ml 125ml 200ml with wood 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 (380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Portable Far Infrared Sauna Dome with Tourmaline Stone.
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