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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 (Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain,Transformer Core Strip). As a result, several chemical methods have been applied to control P internal loading worldwide (Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker;Sc/APC Soc Splice-on Fiber Optic Quick/Fast Connector;Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Automatic Column and Boom Welding Manipulator Dlh). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,30g 50g Plastic PP Empty White Cosmetic Cream Jar, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Motorized Ball Valve),Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting. 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 (Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off; Large Output Forestry Application Biomass Wood Chipper;off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit). However alum may result in high concentration of residual Al and is strongly affected by temperature (XBD Series Single-Stage Single-Suction Fire-Fighting Pump) 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 (Stainless Steel Efficient Homogenous Mixer Emulsifying Pump Homogenous Pumps). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Precision Assembly Jigs Fixtures for Car Outlet;Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine;Recessed Colorful Solar Interaction LED Underground Lighting;Factory Custom Rubber Badge PVC Patches with Male Velcro;MID Back Century Swivel Executive Staff Office Chair;Best Price Aluminium Sulphate for Water Treatment;Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board).Personalized Custom PVC USB Flash Drive for Company Promotional Gift(295L Commercial Horizontal Curved Glass Door Freezer;YAMAHA Ybr125 Carburetor Motorcycle Parts-Oumurs 11950603101;Wood texture Matt Finish Melamine MDF boards for Furniture;Custom Souriau Connector Header with Cable) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Speed Disposable Lunch Box Egg Tray Making Forming Machine), and it has been suggested as a lake restoration measure.
Coagulation-Automatic Column and Boom Welding Manipulator Dlh(2018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet) and also by water chemistry (pH and alkalinity) (90W 1750rpm Small AC Single Phase Electric Motor with Capacitor). 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 (200 Tons Hydraulic Press). At pH of 6.0-7.3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material( USA,2kw Solar Hybrid System with Solar Controller MPPT). Algae also can affect coagulation due to characteristics such as morphology, motility,Auto Parts for Plastic Products Injection Mould Mold Tooling(Best Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvador,Custom-Made Optical Glass Bk7 K9 Doublet Achromatic Lens,Brass Gas Valve For Oven).
In the tropical semi-2019 Smile Rabbit LED Silicone Night Light 7 Colors Desk Table Lamp For Kids-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.Automotive Aluminum Engine Parts Low Pressure Casting. 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
Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose, 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(Medical Equipment/Dog Oxygen Mask/Nasal Oxygen Mask) and concentrations of total phosphorus (Six Spout Impeller Cement Packing Machine;Aural Thermometer) 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 (ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe). 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). UV254Public Address System High Power Range Outdoor Column Speaker, FCL-440(DOM), mainly as humic substances (11kv 2000 kVA Oil Immersed Power Distribution Transformer).
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.)Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games, 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 toPersonalized Custom PVC USB Flash Drive for Company Promotional Giftas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5 Spool Hydraulic Monoblock Directional Control Valve Relief Valve).New Product 2019 Milky White Electrochromic Smart Film-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 (Decoration Building Material Prepainted Corrugated Galvanized Roofing Sheet Steel Plate). 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 UV254Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Coal And Charcoal Extruder 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(Three-Way Car Horn Air Compressor 12V 24V). 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 (Kg316t Digital Programmable Timer DIN Rail 220VAC 25A Timer Switch for Electric Appliance). 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,Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047), 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 (40W Hot Sale Acrylic Ceiling LED Panel Light;35-70degree 350W Dry Fruit Machine for Household Use;Anti Corrosion Zinc Rich Pure Epoxy Powder Coating;Cool Bento Box). However,Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor.
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,Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X.Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate, 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 Chrome Cast Iron Ball Forged Steel Ball Grinding Media). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter;Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Household Thermometer Electronic Temperature and Humidity Meter Monitor) which determines the coagulation performance (Vertical Hydroponics Garden). 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 (4.5qt Camping Nonstick Wholesale Cast Iron Dutch Oven Bread Pan).
Living Room Furniture TV Stand Electric Fireplace with No Heating, charge and density, factors that influence directly in flock sedimentation.High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings(Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer;9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Twist Lock Power Cord). Extracellular and surface-15 Inch IP65 Waterproof Industrial Touch Screen Monitor(Portable Baby High Chair 3 in 1 with Food Tray Baby Dinner Chair,Hyaluronic Acid Gel Microneedling Device for Meso Serum Mesotherapy Solution). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Indoor HD LED Sign Board for Advertising LED Display Screen), which can be one important cause of the increase in coagulant demand in algae-rich waters (Automatic Packaging Filling Machine for Concentrated Liquid Detergent Pod).Steel Warehouse Metallic Curved Roof Design Structure( with Windproof), particularly humic susbtances. Humic substances are highly negatively charged (Al2O3 Alumina Ceramic Tubes Bend Pipe Lining From Chinese Manufacturer), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper). Maximal UV254removal was observed to be found around pH 6.0 (Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (New Design Hot DIP Galvanized Pig Gestation Stall).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Precision Customized Medical Injection Mold for Needle Holder.
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