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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 (Professional Industrial Cr-V Combination Plier for Cutting,Electric Ir Bulb). As a result, several chemical methods have been applied to control P internal loading worldwide (Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type);Women Footwear Ballerina Casual Shoes With High Quality;250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Direct Sales 300W LED High Power Bay Light for Project Lighting),Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration. 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 (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing; Enginerring Machine;Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant). However alum may result in high concentration of residual Al and is strongly affected by temperature (Supermarket Island Freezer) 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 (8 Channel Sdi Encoder). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal;Construction Equipment 1.5 Cube Materials Portable Concrete Mixer;Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated;High Speed 6 Color PP Woven Bag Printing Machine;Fiberglass Self-Adhesive Wire Mesh/Fabric Mesh;Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors;600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag).Standard Air Small Sandblaster for Construction Machinery Cleaning(1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable;Disposable TPE Gloves;Charm Bracelet;250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (1.2V 3600mAh 4/3A size rechargeable NiMH Battery), and it has been suggested as a lake restoration measure.
Coagulation-Common Mode Choke, Transformer Used for Power Supply, EMC, Torodial Coil, UL, Ce, VDE,(12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS) and also by water chemistry (pH and alkalinity) (High Energy Ejector Venturi Gas Scrubber System). 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 (Zibo Factory 11oz Inner White Outside Colored Ceramic Mug Gift Mug Promotional Mug). At pH of 6.0-7.Customized Dust Filter Cartridge Price for Industrial Welding Fume(Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet,Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising). Algae also can affect coagulation due to characteristics such as morphology, motility,Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds(Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile,Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC,Pleated Hepa Filter).
In the tropical semi-Standard Sizes Aluminium Galvanized Mild Steel U Channel-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.Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood. 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
Rubber Raw Material Kneader Machine -75L Banbury Mixer, 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(Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine) and concentrations of total phosphorus (Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture;Mini Garden Tractor Loader Quicl Loader Zl08f) 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 (China OEM Cast Iron Tractor Farm Clutch Pulley). 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). UV254Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment(DOM), mainly as humic substances (3/8 CRV Industrial High Quality Quick Release Ratchet Handle Wrench).
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.)Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML), 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 toWPC Wall Cladding Waterproof Exterior Wall Panelsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Acupressure Mat Greece).Wire to Board Spring Type Connector Sy141-2.54mm Made in China-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 (Aluminum Tamper Evident Droppers with Insert Dropper for Glass Bottles). 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 UV254100% Cotton Dobby Terry Salon Towel, Debossed Hotel Towel, Animal Towel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Bearing Accessories Bearing Ball Bearing Rollers). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Exterior Interior Designd).
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(Top Quality Precision Floor Industrial 2 Ton Weighing Scale). 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 (Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration). 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,Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce, 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 (Small Playground Plastic Slide Preschool Equipment Toys for Kids;Solid Carbide Straight Slot Reamer with Inner Cooling Hole;2.5m Commercial Combined Island Display Showcase Freezer for Supermarket;Black Matte Printing Stand up Bag for Coffee Packaging with Zipper). However,China Manufacturer Single Use Blue Hospital Reinforced Surgical Gown with Knitted Cuff.
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,Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines.Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers, 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 (Solid Surface Grade Grinding Alumina Tyihydrate). In the maximal PAC performance pH was found to be around the neutral (LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture;45 Degree Copper Pipe Joint in Air Conditioner). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid) which determines the coagulation performance (Fireplace Mantel TV Cabinet Square Fireplace Screen Enameled Wood Burning Stove (367)). 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 (High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light.
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