how to develop nitrobacter and nitrosomonas into biological filters quicker? 

1. seed new filter with material from an older well-established biological filter

2. buy cultures of bacteria

what are cultures of bacteria often marketed as 

1. “water conditioners”

what is denitrification? 

1. conversion of nitrate into nitrogen gas or nitrous oxide

what is usually the carbon source for denitrification? 

1. methanol or acetate, or fish wastes and uneaten foods

what kind of reaction is denitrification?

1. reduction reactions, must be done in anaerobic environments

what is “dissimilarity nitrate reduction”?

1. if the C/N ratio gets too high in a system, causes a shift in metabolic pathways

what are chemical filters? 

1. used to remove substances dissolved in water

what is foam fractionation? 

1. use of bubbles for removal of solute

what are foam fractionation units also called? 

1. “protein skimmers”

what is carbon filtration? 

1. used to take out both polar and non-polar molecules

what is water passed through in carbon filter? 

1. activated carbon

what does “active” mean in carbon filters? 

1. many pores on the carbon, increases surface area for reactions

how can activated carbon be produced? 

1. physical activation and chemical activation

why should carbon filters be downstream of biological filters? 

1. need to remove nutrients before they get to the carbon, or bacterial colonies will grow over the carbon and block absorption

what is ion exchange? 

1. removes unwanted ions from a solution and replaced them with desirable ones

what is resin in ion exchange? 

1. when the resin is manufactured, a certain type of ion is bound to the material, results in ion exchange

most commonly used resins

1. zeolites or polystyrene sulfonate beads

where should exchange resins be placed in a system? 

1. downstream of foam fractionators or activated carbon filters

what is disinfection?

1. reducing harmful microorganisms from water

how is UV radiation used in disinfection? 

1. electromagnetic waves disrupt unsaturated bonds of molecules; are not killed immediately but are unable to grow and reproduce

benefit of UV

1. cheap to operate (although expensive to buy) and cannot overdose on UV 

what is ozone?

1. O₃, unstable, bluish gas

2. very strong oxidizing agent

what should ozone be broken down into? 

1. O₂ before going to a culture system

how is O₃ converted to O₂? 

1. UV radiation

what is another benefit of ozone (other than disinfection)?

1. oxidizes many organic and inorganic substances

2. removes color and smells from water

what is chlorination? 

1. use of chlorine to disinfect water

what is Cl₂ sold as? 

1. liquefied gas under pressure

2. calcium hypochlorite powder

3. sodium hypochlorite liquid

what does chlorine in water form? 

1. hypochlorous acid

what pH is chlorination more effective? 

1. lower pHs

what is chlorine demand? 

1. amount of chlorine needed to react with dissolved compounds and microbes in the water

what are chloramines? 

1. formed from chlorine and ammonia

what pH do chloramines work more effectively? 

1. higher pH’s

three methods of dechlorinating water

1. pass water through activated carbon or ion-exchange resins

2. UV radiation

3. sodium thiosulphate

what is sodium thiosulphate? 

1. reacts with chlorine and neutralizes it

what is a gravity aerator? 

1. water is raised, then falls back into pond after being broken into droplets or mist

what is diffuser aerator? 

1. injects air into the water

what is a venturi diffuser? 

1. water is pumped at a high speed and air is drawn in through a valve

what is a U-tube diffuser? 

1. water is pumped into a U-shaped tube, simple diffuser at entrance

what is a down-flow aerator? 

1. water forced downward in hood, oxygen is injected into it, creates bubbles

what is a surface aerator? 

1. water is thrown up rom pond surface into the air

types of surface aerators

1. nozzles, spray aerators, floating paddle wheel

what is a turbine aerator? 

1. not so much to add oxygen

2. moves aerated water, especially for moving surface water below a pond thermocline

what is a thermocline? 

1. rapid change in temperature with depth

what is degassing? 

1. removal of supersaturated gases from water, usually N₂

what can supersaturated waters lead to? 

1. gas bubble “disease”

three common degassing methods? 

1. vacuum - gas leave under reduced pressure

2. oxygen injection - O₂ is bubbled into water, forces N₂ out

3. packed column - agitation of water releases some of the N₂

ways to control temperature

1. insulating tanks and pipes can help retain heat in colder climates and prevent heat gain in warmer climates

what kind of heaters are used? 

1. immersion heaters or in-line heaters