WASTE MANAGEMENT IN AQUACULTURE
Aquaculture Information SeriesPublication #AQ02-1Waste Managementin AquacultureDan Miller and Ken SemmensExtension Service Agricultural and Resource Economics ProgramDivision of Resource ManagementCollege of Agriculture, Forestry, and Consumer SciencesWest Virginia UniversityMorgantown, WV 26506-6108Version 1.0–January 2002
This material is based upon work supported by the Cooperative State Research, Education, and ExtensionService, U.S. Department of Agriculture, under Agreement Number 98-34386-6849. Any opinions,findings, conclusions, or recommendations expressed in this publication are those of the author(s)and do not necessarily reflect the view of the U.S. Department of Agriculture.The authors are respectively, Dan Miller, Senior Project Coordinator-Aquaculture, and Ken Semmens,Aquaculture Extension Specialist, West Virginia University, Morgantown, WV.WVU Extension Service CommunicationsDesign, Pat Kerns; illustrations, Nathan Hamric.
WASTE MANAGEMENT IN AQUACULTUREBest management practices to reduce aquaculture wasteThe growth in aquaculture has led to an increasein the use of feeds applied to water for improvedproduction. The wastes that result from the use ofaquaculture feeds are the focus of this paper. InWest Virginia the annual production of trout andchar in commercial operations is approaching700,000 pounds. Compared to beef production thislevel is insignificant; however, as the industrygrows we must consider that our water resourcesare limited and efforts must be made to sustain orimprove the quality of the aquatic resources in thestate.With increased interest in environmentallyfriendly farming practices, and the potential forregulatory action by the EPA and other agencies,the aquaculture industry has been focusing onways to reduce the wastes (environmental impact)from aquaculture facilities. By choosing theappropriate feeds during the production cycle, andpaying close attention to the feeding methods andthe resulting solids production, the manager cangreatly reduce the wastes. For example researchshows that combining quality feeds with carefulmanagement in a well designed culture system andsolids collection area, can reduce nutrientdischarges by as much as 50% (Hulbert, 2000). Ifthe facility is going to be built or modified, greaterreductions can be made.The Federal Clean Water Act requires theindustrial discharge of water to meet Federalstandards. Enforcement of this law in WestVirginia has been delegated to the state of WestVirginia'sDepartmentofEnvironmentalProtection. This law is not similarly enforced in allstates because the classification of aquaculturevaries from state to state (Ewart, 1995).Agricultural wastes have less stringent restrictionsthan industrial based wastes. Some states haveclassified aquaculture as an agricultural activity.Presently, in West Virginia the laws categorizeaquaculture waste as an industrial waste. Adischarge permit (NPDES) is required if a facilityis discharging more than 30 days per year orproducing above 20,000 lbs. per year1.Many of the fish farms operating in WestVirginia do not use filters or ponds to reduce theamount of waste that leaves the farm. This resultsin negative externalities that are often more costlythan if the farmer were to treat the waste on thefarm. New regulations by the EPA are expected,and these regulations may be based on TotalMaximum Daily Load (TMDL's) rather thanconcentration limits (mg/l). MDL permits are usedin Europe and Idaho and have been shown to beeffective. Idaho’s Division of EnvironmentalQuality has published useful information onaquaculture waste management (Idaho . Each watershed can have differentlevels of nutrients or water uses, and thereforeregulations may vary, depending on the ambientlevels of nutrients in the watershed. Another factorinfluencing the discharge regulations is theintended use of the water in the watershed. Publicwater supply, trout waters, recreational, andindustrial uses will have an impact on thepermitted discharge limitations.Point source treatment is also known as "costinternalization" to economists. If the industry is tobe sustainable, the cost of waste treatment must beinternalized.The best management practicesreferred to in this paper can help reduce the costoutlay to accomplish this. These costs will beaddressed after defining different types of waste.Wastes from a fish farm come in three generalforms: metabolic, chemical, and pathogenic.Feed ManagementDuring the past decade, feed and nutrition researchhas shown the importance of ingredients in troutfeed. By selecting grains low in phytate for theformulation of trout feeds, less phosphorus will be1Chief of Water Resources phone: 304-558-21071
released by the fish. The majority of thephosphorus in plant proteins is not absorbed bytrout because it is not digested in animals withonly one stomach (Hardy, 1999).Anotherapproach, to increase the bioavailability andutilization of phosphorus in feeds, is to increasethe level of phytase in the feed (Baker et al., 2001;Papatryphon, 1999; Jackson et al., 1996). Thisapproach is more effective in warm water species.The lower water temperatures associated withtrout culture reduce the impact of phytasesupplementation (Rodehutscord and Pfeffer,1995). The relationship in trout betweenincreasing phosphorus retention and 3-phytase introut feeds was shown to be most effective withlevels of phytase between 500 and 2000 FTU/kg(Baker et al., 2001).The selection of extruded, high-energy feeds isanother management tool that can be used toreduce waste. Recently the high-energy extrudedpellet has been shown to reduce feed conversionsin trout without a reduction in growth, therebyreducing waste (Bender et al., 1999). The fatcontent can be increased without using the coatingmethod, which allows the fat to be introducedbefore the pellet is formed, thereby giving a morehomogeneous mix. Extruded feeds can be made tosink or float. Floating feeds provide another toolthat the manager can use to avoid overfeeding.Uneaten feed will remain visible as evidence ofoverfeeding. The higher cost of these feeds is themain reason that more farmers do not use them.When the reduction in the cost of wastemanagement is considered, along with the reducedfeed conversion ratios, high energy extruded feedshave proven to be more economical than regularpelleted feed.By minimizing feed handling and storage timefeed conversions can be improved. Excessivehandling results in a greater percentage of finesthat are generally not eaten by the fish. Regulardeliveries and a good inventory system will keepthe feed fresh. This is especially important in thehot summer months when the storage life of feedis reduced.Solids Removal and Metabolic WasteMetabolic waste comes in two forms: dissolvedand suspended. When determining the amount ofwaste a system will generate, the amount of feedused in a system is the most important factor. In aproperly managed farm, approximately 30% of thefeed used will become solid waste. Feeding ratestend to increase with temperature, so the amountof waste is often greatest in the summer monthswhen feeding rates are highest. Besides choosing ahigh energy extruded feed for greater assimilation,waste management efforts will be most effective iffocused on the quick removal of solids. Primarytreatment, or solid waste removal, should be doneas soon as possible to reduce waste fragmentation.Fragmentation causes leaching of nutrients intothe water. Excessive waste accumulation has beenknown to cause disease in fish culture operations.Water flow patterns in production units areimportant for waste management because a properflow will minimize the fragmentation of fish fecesand allow for rapid settling and concentration ofthe settleable solids. This can be critical because ahigh percentage of nonfragmented feces can bequickly captured which will greatly reduce thedissolved organic waste (Mathieu and Timmons,1993). A reduction in downstream pollution is bestachieved by the rapid removal of solids in thesettleable form before discharge to public waters.By settling out downstream, solid wastes coverbenthic animals and reduce oxygen levels, whichreduce the biodiversity of a stream.Dissolved WasteDissolved waste is another component ofmetabolic waste. It comes in the form ofbiological oxygen demand (BOD), and chemicaloxygen demand (COD). BOD is considered along-term measure of the consumption of oxygenbecause it may not occur until long after the waterleaves the farm. On the other hand COD is a shortterm measure because the loss of oxygen occurs,for the most part, within the farm.Dissolved waste occurs in many forms:ammonia, nitrite, nitrate (i.e.; nitrogen),phosphorus and organic matter. Ammonia, whichis excreted through the gills, is the most toxic form2
of nitrogen when in the un-ionized form. Naturallyoccurring bacteria convert ammonia into less toxicforms that are utilized by plants and algae forgrowth. Providing a large surface area forautotrophic bacteria to grow is the best way toconvert the ammonia to less toxic forms.An increase in suspended solids will result in anincrease of BOD (Alabaster, 1982). That is why ahigher portion of settleable solids, quicklyremoved, will reduce the dissolved portion (BODand COD) of waste from the farm. Generally, thesmaller a particle is, the more leaching will takeplace. The majority of the solids produced inaquacultural operations are particles measuring 30microns or less (Boardman et al., 1998; Chen etal., 1993). Small particles also take longer forsettling to occur.Phosphorus is found in fish feeds and is brokendown into a more useable form (phosphate)through decomposition. In nutrient limited waters,phosphorus can be desirable for improving thebenthic and planktonic community in a stream. Infresh waters, phosphorus is often the limitingnutrient for productivity. In most on in a watershed by promotinggrowth of algae or plants. Watershed resourcemanagers focus on reducing the amounts ofphosphorus and nitrogen in a watershed whenattempting to improve water quality.Harvesting of fish occurs regularly on a farm. Itis during the harvest and cleaning of tanks orponds that elevated levels of waste are released.In particular, the final 25% that drains from a pondnormally contains the majority of the metabolicand pathogenic waste. Frequent removal of solidwastes will reduce the dissolved wastes in theoutflow from the farm.Chemical WasteThe use of chemicals on fish farms is regulatedby state and federal laws. Although there are fewchemicals that are allowed to be used on food fish,a detoxification procedure should be followed,according to the manufacturer's label associatedwith the chemical treatment. Salt is a commonlyused stress reducer in fish and has been approvedfor use in foodfish.Pathogenic WasteWater treatment plants often use some form ofdisinfection to reduce the parasitic, bacterial, andviral particles that flow from the plant. Fish farmscan contribute to an increase in potentiallypathogenic organisms. The three most commonmethods to reduce pathogens from water ischlorination, ultraviolet radiation and, ozonation.UV radiation occurs in a chamber and is notharmful to life downstream from the treatment.Both chlorine and ozone are strong oxidizers andhave been responsible for fish kills due toexcessive concentrations in the water.West Virginia regulations do not require fishfarms to treat for pathogenic wastes. The optionslisted above are available but generally areconsidered unnecessary and too costly toeffectively treat all water discharged from mostfarms, especially if it is a flow through operation.Pathogens can be removed in wetlands viasedimentation and filtration. Macrophyte rootshave been reported to have antibacterial properties(National Small Flows Clearinghouse). Bacteriaare causes of numerous diseases in fish.Pseudomonas and Aeromonas are often presentand can cause significant mortality in stressfulconditions.Methods for Waste RemovalRaceway and Tank DesignProper engineering can be an economical meansof controlling the wastes from a fish operation. Bycontrolling the flow of water through a system,most solids can be collected and concentratedbefore fragmentation occurs. Round tanks can bedesigned with dual effluent areas. The highvolume-low solids flow, can exit the tank from theupper perimeter while a low volume-high solidspipe, in the center of the tank, will remove mostsettleable material (Summerfelt and Timmons,2000). Circular tanks with properly designedinlets, drains, and filters can remove the majorityof solids with minimum labor. Centrifugal forces3
will move settleable solids to the center drainwhen water velocity exceeds 20 cm/sec. (Burrows,1970).Vacuum removal of solids can be laborintensive. In raceways, if the flow is less than 3cm/sec. non-fragmented trout feces will settle outif fish cannot stir the bottom. Figure 1 shows atypical raceway system with waste managementoptions. Raceways should be designed with anoptimum flow, which will allow an area at the endof each raceway, called the quiescent zone, tocollect settleable solids for periodic removal bythe operator.Concrete raceways are difficult to modify onceconstructed. Research is planned to improve thewaste collection abilities of raceways by insertinga device that will create a circular flow to collectthe majority of the solids in the center. Like theround tanks, the concentrated waste can beremoved by allowing 10-20% of the flow to exitfrom the center (Wong and Piedrahita, 2001).Research is underway at WVU to developraceways made of alternative lighter materials,that will permit more flexibility in design.Rectangular raceways can be designed to channelwater into a circular pattern before exiting theunit. This will allow most of the settleable solidsto be concentrated and removed from the centerwhile most of the water flows out the end, into thenext rectangular raceway.TransformationDissolved organic waste (phosphorus andnitrogen) is a nutrient for plants. Biofilters willtransform a toxic form of nitrogen (ammonia) intoa nontoxic form (nitrate), which is a nutrient formany algae. Artificial wetlands have also beenused for waste treatment in aquaculture operations(Summerfelt et al., 1995). In a wetland, sedimentsare trapped and used for grass and aquatic plantgrowth. Various types of vegetables and herbshave been produced using hydroponics withrecirculating water from fish operations. In orderfor the herbs or vegetables to significantly reducethe nutrient level in a commercial recirculatingsystem, the time spent on fish culture can becomesecondary to the plant cultivation and marketing(Rakocy, 1999). In all of the above methods,nutrients are transformed or removed from thedischarge with the help of common plants andbacteria.FiltrationDrum, disk, bead, and sand filters are commonlyused to trap and remove particles as small as 60microns from the water. Cartridge filters willremove particles down to 1 micron but that levelof purification is usually not necessary, and verycostly. High volume flows require expensivefiltration units. With flows of 1000 gpm andabove, the maintenance and cost of mechanicalfilters become burdensome. That is why the dualdrain design, mentioned earlier, works well. Bytreating only the low flow of concentrated solids,the cost of treatment can be greatly reduced byusing smaller filters. If land is available a settlingpond would be another inexpensive option.Radiation / OzoneUltraviolet radiation is used for disinfection ofwater. Many pathogens, including viruses can bekilled with relatively low levels of radiation. ForUV treatment to be effective the solids must beremoved before treatment. UV systems are a lowmaintenance, low risk method of disinfection.Low levels of ozone dissolved in the water willalso remove most pathogens. Ozone will improveparticulate filtration and reduce the dissolvedorganic waste in the water. Low levels of ozone inthe air are detrimental to human health. Residualozone is toxic to fish at low levels and should bemonitored.CostsFlow through systemsIn a study published in 1997 the internalizedcost, or pollution prevention cost, of flow throughsystems, was determined to be .05/lb. of fishproduced. This compared favorably with thepollution damage cost, or the external cost, whichwas estimated to be .22/lb. (Smearman et al.,1997). If the industry approaches the waste4
problem from a long-term sustainable path, theefficient and economical way to deal with theproblem is to internalize the cost. According tothe study, in a flow through system, the cost for aproducer of 20,000 lbs./yr. would be about 1,000/yr. if it were internalized. The level atwhich a producer would need to address wastemanagement is determined, in many states, by theannual pounds of production or the annual feedconsumption for the operation. In West Virginia aproducer is regulated if the annual productionexceeds 20,000 lbs./year. There are few producersabove the 20,000 lb./year level, however the statemay inspect these sites.Settling BasinsThe Engineering Department at WVU has begunresearch using a new composite material forportable raceways that will investigate thequiescent zone design, and how efficientlydifferent designs remove solid waste. The initialphase of this research should be completed in2003. When this data becomes available ananalysis of the economics can be conducted todetermine the cost-effectiveness of modified inraceway quiescent zones compared to settlingponds or basins.Ponds can be a very efficient means of settlingout wastes from an aquaculture operation. If anexisting pond is located below the productionfacility, and has a residence time of at least a day,the cost for solid waste removal will remain low.It is difficult to predict the cost of a pond becauseevery site is unique and existing infrastructureshould be used to reduce costs.Recirculating systemsIn recirculating systems dissolved organicsaccumulate and can be removed with proteinskimmers or foam fractionators. Ozone, which is adisinfectant, is also very effective for removal ofdissolved organics. However, due to its cost, it isgenerally economical in intensive recirculatingsystems producing a high value ( 3/lb)product.Biofilters can transform a limited amount ofammonia each day. This transformation rate isusually the first limiting factor for production inrecirculating systems. The management ofbiosolids can have a great impact on all of thecomponents in the system. For a recirculatingsystem that produces 20,000 lbs./yr. the averagedaily feeding rate would be approximately 80lbs./day. In a well-designed system the solidsshould be removed rapidly and only high qualityfeeds should be used.The additional cost of tank design and filters thatare necessary for proper waste management of a20,000 lb./year system would be estimated atabout 8,000. These expenses could be amortizedover a 10-15 year period. The collected wastescould be used for field applications if lawspermitted. With proper management, total solidwaste for an operation of this size (from 25,000lbs. of feed/yr.) should not exceed 8,000 lbs./yr.Assuming there is an adjacent field for theapplication of the concentrated solids, and laborcosts of 500/year for transportation and fieldapplication, the annual cost for waste managementper pound of production would be .065/lb.,similar to the cost in flow through systems. Fieldapplication rates are determined by the slope, soiltype, precipitation, temperature, nutrient content,and plant type.Constructed WetlandsConstructed wetlands are artificial shallowwastewater treatment systems (ponds or channels)that have been planted with aquatic plants, andrely on natural processes to treat wastewater.Constructed wetlands have advantages overalternative treatment systems in that they requirelittle or no energy to operate. If sufficientinexpensive land is available close to theaquaculture facility wetlands can be a costeffective alternative. Wetlands provide habitat forwildlife, and may be aesthetically pleasing to theeye. The disadvantages are that wetlands requiremore land area than alternative systems. Wetlandsfunction best as a secondary treatment for water(after most solids are removed). They require aprolonged start-up period until vegetation is well5
established, and seasonal efficiencies occur thatresult from a decrease in sunlight and temperature.It is important to control the hydraulic and solidsloading rate so as not to overload the system.Substrate clogging is often a problem withconstructed wetlands. For this reason theaquaculture effluents need to be monitored toknow the suspended solid size and nutrientconcentrations of the effluent before it enters thewetland. Standard methods can be used for thisanalysis.Constructed wetlands for aquaculture wastetreatments have been reported to be useful forfrom five to ten years (Reed et. al., 1995). Anexcellent publication on wetland design,maintenance, and treatment results is availablefrom the Environmental Protection Agency /NRMRL).Simplemethods can be used to construct a wetland. Theyhave been shown to remove more than 95% of thetotal suspended solids and 80% - 90% of thenitrogen and phosphorus when application ratesare about 30 kg. solids/sq. meter/ year(Summerfelt et.al., 1996).Using constructed wetlands for primarytreatment of wastewater is not recommended(EPA, 2000).For catfish production inMississippi the additional cost of a constructedwetland per pound of production was 0.075/lb.(Posadas and LaSalle, 1997). However, over threequarters of the construction cost was in thepurchase and planting of mature plants needed toconduct the experiment. Much of this expensecould be avoided by planting seedlings and lettingthem mature before heavy loads are introducedinto the wetland. For a well designed aquacultureoperation of 20,000 lbs./yr. where the settleablesolids could be field applied, a constructedwetland of 150 square meters should be sufficientto remove most of the suspended solids,phosphorus and nitrogen. The estimated cost forconstruction of a wetland for secondary treatmentmeasuring 150 square meters is about 5,500 or 37/m2 (see Appendix 1), and is estimated to last5-10 years without major maintenance. Factorsthat impact the nutrient removal rate in wetlandsare: hydraulic retention time, type of vegetation,solar radiation, microbial activity, and temperature(Hammer, 1993; Hammer and Bastian, 1989; Reedet al., 1995). A wetland design should be sitespecific, selecting local hardy plants (bulrushes orcattails).There are two main types of constructedwetlands used for water treatment; surface flowand subsurface flow. Surface flow systems cantreat large volumes, and subsurface flowsgenerally are used for smaller flows. Because eachsystem is highly site specific due to the slope, soil,shade, elevation, temperature, and other variables,the construction costs will vary considerably. Thedrain location will determine whether the flow ishorizontal or vertical. Greater oxygenation can beachieved with parallel systems receivingintermittent flow. By alternating between wet anddry conditions within the substrate, BOD,ammonia, and phosphorus reduction is very good(Negroni, 2000).Assuming that the constructed wetland would beused as a secondary treatment solely for a mediumsized aquaculture facility in West Virginia, thesubsurface design would probably work best. Thesubsurface flow also eliminates mosquitoes frombreeding in the water. Plant selection is anotherimportant criterion for efficient water treatment.In the Northeastern U.S. some of the commonplants used in constructed wetlands are cattails,bulrushes, rushes, and sedges. Selection of themedia material is also crucial. Systemperformance will depend on media size,uniformity, porosity, hydraulic conductivity andphosphorus binding capacity. Locally availablemedia (river gravel) will reduce costs.AsubsurfaceconstructedwetlandinEmmitsburg, MD measuring 0.07 hectares (700sq. meters.) cost less than 35,000 to build(National Small Flows Clearinghouse WWBKDM38). This same source indicatedanother study in Arcata, CA, which had capitalcosts of 41,000/ha. for a 12.6 ha. wetland. Thehydraulic surface loading, and influent nutrientload will determine the appropriate size of awetland. Typical wastewater retention times in aconstructed wetland range from two to six days.Wetlands can be designed to meet specific effluent6
criteria if the influent characteristics includingmaximum TSS and BOD are known (EPAManual).process. Good record keeping with experimentscan help develop an efficient compost processwithin the first year.Waste UtilizationConclusionsAquaculture waste can be utilized in much thesame way that agriculture waste is used to amendthe soil for crop production. State laws may notpermit land application of aquaculture waste untilaquaculture waste is clearly classified as anagricultural waste and not an industrial waste.Other options for waste utilization include theproduction of hydroponic plants or composting forgarden applications.Sustainable growth of the aquaculture industryrequires profitability, economic development, andwaste management. Waste management decisionsmust be made on an individual basis due to sitecharacteristics on the farm and within thewatershed. Research has shown that round tankscan be more efficient at waste removal thanrectangular or square tanks. Dual drains allow forcontinual removal of concentrated waste while themajority of the flow can be reused or dischargedcontaining minimal waste. The circular flowprinciple has been used to retrofit existingraceways by modifying the flow in the quiescentzone. (Wong and Piedrahita, 2001)Acute or chronic mortalities occur at some pointin time and the dead fish need to be disposed of ina proper manner. Composting is a useful way ofutilizing the dead fish, as a nitrogen source to bemixed with sawdust, or another carbon source, forthe production of mulch. The process needsregular attention and aeration if it is to be doneproperly. Mortalities can be considered a solidwaste and should be treated as such.Composting is a sustainable option, and if doneproperly can generate a minor revenue for thefarm. Fish carcasses, which are high in nitrogen,should be mixed with a material high in carbonsuch as wood chips in an attempt to attain a C:Nratio of 30:1. A few essential elements needed forsuccessful composting are: a moisture content of50-60%, porosity of 35-50%, pH should be 6.58.0, temperature between 130-1500F, a C:N ratioof 25-35:1, and a particle size of ¼”-3/4”.Aerobic composting requires an oxygenconcentration of 5%. Generally if theseparameters are maintained a quality compost canbe obtained in two to four months. Anaerobiccomposting can convert wastes into compostquicker than aerobic composting, however thereare odors and methane production that can causeserious trouble. Temperature is a key processcontrol factor and should be monitored closely.Pathogens and parasites can be controlled bymaintaining the temperature above 131oF (55oC).Any one of these factors can delay the process andeach carbon and nitrogen source has differentqualities which can impact the compostingSignificant reductions in waste can be made bymanagerial decisions focusing on all aspects of thefeed, including digestibility, ingredients, handling,storage, and presentation, without an interruptionin production. Rapid solids removal will minimizeshearing of solids which results in an increase ofdissolved wastes which are more difficult toconcentrate and remove from the system.Understanding waste characteristics is importantin the design of a waste management system. TheNPDES permit application will require knowledgein this area. The first step in waste treatment is theremoval of larger (settleable) solids. This iscommonly done with filtration systems andsettling basins or ponds. The second step is theremoval of smaller (suspended) solids, thoseparticles less than 60 microns, and dissolvednutrients. This is can be done using polishingponds, constructed wetlands or hydroponics. Thethird step in waste treatment is disinfection.Ozone, chlorination, and ultraviolet radiation areall effective means of disinfection.Although the costs incurred with wastemanagement seem high, they are minor comparedto the costs of controlling the pollution after it hasleft the farm and entered the environment.7
Proper application of biosolids from anaquaculture operation requires knowledge on soiltype, slope, crop development, seasonal rainfalland other issues.the watershed, before being implemented. Policyoptions to address this issue include, cost-sharing,incentives, feed related taxes, education, and waterquality testing that would be used to establish totalmaximum daily loads (TMDL).Regulatory actions will need to consider theultimate use of the water and the characteristics of8
APPENDIX 1Estimated Wetland Construction CostsFeeding level not to exceed 30,000 lbs. / yearWith 30% sludge production: 10,000 lbs. sludge producedPrimary treatment: removes 70% of solids; 3,000 lbs. solids /yr. enter wetland3,000lbs. solids / 150 sq. meters 20 lbs. solids/ sq. meter/ yr.Sludge application rate: 20 lbs. solids / square meter / year150 square meter area with 10 cm of coarse sand over 40 cm of gravel.150m2 x 0.10m(deep) x 20/m3(sand) . 300150m2 x 0.40m(deep) x 28/m3(gravel) . 1,680Backhoe 75/ hr x 16 hours 1,200Labor at 10/ hour (preparation)x 60 hours . 600Estimated cost for plants: 1,200PVC pipe . 300Misc. . 320TOTAL: 5,600 5600 / 150 m2 37 / m2 for construction costs.With a 5 year estimated life span for secondary treatment, and fish production of 20,000 lbs. / year. 5,600 / (5 years x 20,000 lbs./yr.) Cost per
classified aquaculture as an agricultural activity. Presently, in West Virginia the laws categorize aquaculture waste as an industrial waste. A discharge permit (NPDES) is required if a facility is discharging more than 3
Aquaculture Without Frontiers Aquaculture education (including minority institutions) Market driven aquaculture: developing and sustaining an industry Aquaculture Economics Ecology & Environment Policy & regulations Organic Aquaculture: Future Opportunities Certification Endangered species Frogs Water Quality & Effluents Extension/Technology .
5. World aquaculture production of food fish and aquatic plants, 1990–2016 17 6. Average annual growth rate of aquaculture production by volume (excluding aquatic plants) 18 7. Aquaculture contribution to total fish production (excluding aquatic plants) 19 8. Fed and non-fed food fish aquaculture production, 2001–2016 22 9. Aquaculture .
Aquaculture Without Frontiers Aquaculture education (including minority institutions) Market driven aquaculture: developing and sustaining an industry Aquaculture Economics Ecology & Environment Policy & regulations Organic Aquaculture: Future Opportunities Certification Endangered species Frogs Water Quality & Effluents Extension/Technology .
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3. Urban waste generation by income level and year 12 4. Waste collection rates by income 15 5. Waste collection rates by region 15 6. Waste composition in China 17 7. Global solid waste composition 17 8. Waste composition by income 19 9. Solid waste composition by income and year 20 10. Waste composition by region 21 11. Total MSW disposed of .
Integrated Solid Waste Management Generation-Source Perspective Residential Collection of Waste Segregation of Waste Recycling waste (organic & inorganic) Waste Exchange Discarded waste Treatment Recovery Final waste Final disposal Hazardous Waste for Treatment & Disposal 3R Services (Healthcare, Laboratory, etc.) Industrial &
4. Identifying waste/garbage that can be reused and/or recycled 5. Describe waste/garbage disposal of the family 6. Recognize words related to waste management by sight 7. Read sight words related to waste management. 8. Read sentences illustrating proper waste management. 9. Practice proper waste management such as waste segregation and 3R 10.
I am My Brother’s Keeper (2004) As our New Year’s celebration draws near, I once again find myself pondering the enigmatic story that our tradition places before us at this time—the story of the Binding of Isaac. Once again, I walk for those three long days with father Abraham and ponder the meaning of his journey with his son to the mountain. And once again, I find fresh meaning in the .
