Turbidity of the reactor feed solution was measured usmg a HACH 2 1 00P Turbidimeter, calibrated with manufacturer supplied standards.
3. 1 2
Determ in ation of DNA
Total DNA content of the activated sludge mixed liquor was measured usmg the method outlined in Marshall et al., ( 1 98 1 ).
Three main types of reaction vessel were used in this study: a 1 0 litre working volume completely mixed reactor with external settler, a 6.25 I working volume completely
mixed reactor with an internal settler and a 1 litre working volume respirometer.
The 'respirometer' used for many batch tests and kinetic parameter estimations consisted of a cylindrical 0. 1 m internal diameter perspex vessel with a working volume of 1 litre as detailed in Figure 3 . 1 and based on the design described by Cech et al. ( 1 984). These respirometers were constructed specifically for this use in the Department of Process and Environmental Technology (PET) workshop, Massey University.
Constant temperature conditions were maintained by placing the respirometer In a waterbath at the desired temperature, or placing the stirred respirometer on a Heidolph MR 300 1 heated plate magnetic stirrer.
Top view
/
0o
ort for thennometer
Side view
Igure 3.1: 'Respirometer' vessel schematic.
Port for DO probe
Port for substrate addition and for air supply l ine
O-ring seal - between lid and
body of ' respirometer'
Internal wall baffles
Aeration was supplied via a length of flexible tubing connected to a filtered, pressurised air supply. The tubing was immersed in the respirometer contents through the air port in the respirometer lid and air flowrate was adjusted as needed using a screw clamp on the tubing.
A DO probe could be immersed directly into the respirometer contents via a specificaHy sized port, and a third sealable port was available for the addition of chemicals and for exit airflow during aeration.
3.13.2 6.25 litre M ixed Reactor with Internal
This reactor was used for initial biodegradability studies and to supply acclimated biomass for batch tests, as described in Chapter 4. The rectangular reactor was constructed of perspex by the PET Department, having a total volume of 1 0 litres and liquid level control via a stainless steel overflow pipe through the reactor base.
A porous stone diffuser located centrally at the base of the reactor provided both aeration and mixing in the vessel. The overflow pipe was positioned to maintain a working volume in the reactor of 6.25 litres. Feed to the reactor was delivered via a Cole Panner Model 7554-30 Masterflex pump and controller, fitted with a 70 1 3-20 pump head and Norprene Masterflex tubing.
The continuous activated sludge trials were conducted using a New Brunswick Scientific Co. Model MF- 1 4 bioreactor with a 1 0 I working volume glass vessel. The bioreactor had adj ustable stirrer, air flowrate and temperature control. The stirring rate in the reactors was maintained at 1 00 rpm, air flowrate at 7 lImin and temperature at 25 °c for all activated sludge trials.
The reactor used an external settler, which was an 0. 1 1 m internal diameter cylindrical perspex container with a sloping base, notched overflow weir and 1 .75 litre working volume. A wire stirrer rotated at approximately 4 rpm at the base of the settler to prevent floc bridging at the settler outlet.
Flowrates in and out of all the activated sludge system vessels were controlled using Cole Panner Model 7554-60 or Model 7554-30 Masterflex pumps fitted with 70 1 4-20
or 70 1 6-20 pump heads and Norprene Masterflex tubing.
3 . 1 4
All chemicals used were analytical reagent grade, unless specified.
Reactor Feed Whole Milk Powder Skim Milk Powder Butter
Lactose
'Anchor' brand, NewZealand Dairy Foods Ltd, Auckland, NZ. 'Anchor' brand, NewZealand Dairy Foods Ltd, Auckland, NZ. 'Anchor' brand, NewZealand Dairy Foods Ltd, Auckland, NZ. BDH, Poole, England.
NaOH 'Prolabo' brand, Rhone Poulenc ltd, Paris, France.
Potassium hydrogen thalate K2Cr207
HgS04 H2S04 Ag2S04
BDH, Poole, England.
'Univar' brand, Ajax Chemicals, Auburn, Australia. BDH, Poole, England.
'Univar' brand, Ajax Chemicals, Auburn, Australia. BDH, Poole, England
(NH4)6Mo7024.7H20 'Univar' brand, Ajax Chemicals, Auburn, Australia . . NH4 V03 'Univar' brand, Ajax Chemicals, Auburn, Australia.
HCI 'Univar' brand, Ajax Chemicals, Auburn, Australia.
KH2P04 'Univar' brand, Ajax Chemicals, Auburn, Australia. HACH Amino Acid Reagent HACH Cat. No. 1 943-32
HACH Molybdate Reagent HACH Cat.No. 2236-32
NaOH Disodium hydrogen orthophosphate. 1 2H20 Sodium salicylate Na2(NO)Fe(CN)s,2H20 NaOCI(4% solution) NaCI
'Prolabo' brand, Rhone Poulenc ltd, Paris, France. 'Univar' brand, Ajax Chemicals, Auburn, Australia.
'Univar' brand, Ajax Chemicals, Auburn, Australia. BDH, Poole, England
'Janola' brand, Reckitt and Coleman, Auckland, New Zeal2.nd
'Prolabo' brand, Rhone Poulenc ltd, Paris, France.
3.1 4.5 Nitrate Determination CuS04·5H20 ZnS04·7H20 NaOH Hydrazine sulphate Sulphalinimide N-(1 -naphthyl) ethylene diamine dihydrochloride Merckoquant 1 0 020 Nitrate test strips
'Univar' brand, Ajax Chemicals, Auburn, Australia. 'Univar' brand, Ajax Chemicals, Auburn, Australia. 'Prolabo' brand, Rhone Poulenc ltd, Paris, France BDH, Poole, England
BDH, Poole, England BDH, Poole, England
MERCK
HACH Nitriver 3 Reagent Powder Pillows. HACH Catalogue No. 1 4065 - 66.
NaOH Phenol
NaKC4H406.4H20
'Prolabo' brand, Rhone Poulenc ltd, Paris, France. BDH, Poole, England
BDH, Poole, England
3.14.8 Acid and TP Determination
H2S04 ' Univar' brand, Ajax Chemicals, Auburn, Australia. K2S04
Selenium powder
'Univar' brand, Ajax Chemicals, Auburn, Australia. BDH, Poole, England