Optimising nutrient ratios for wastewater treatment - HACH LANGE

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NUTRIENTS_CALCULATION
Controlling nutrient ratios
SC 1000 controller for up to eight
sensors is also suitable for use as a
network with Profibus
Partially immersed NITRATAX
sc probe for online nitrate
measurement
However, all sorts of industrial plants,
regional differences in eating habits
(disposal of different kitchen wastes
through the drains), and the nature
of the soil and drinking water cause
wastewater to vary widely in its
composition. Experience has shown that
the C:N:P ratio in municipal wastewater
is about 100:20:5.
The excess N and P compounds
can usually be eliminated from the
wastewater without any great difficulty
using modern methods.
Table 3: Causes and effects of nutrient deficiencies in the biological stage of wastewater treatment
Shortage of Causes/Origin of the wastewater Possible consequences Corrective action
Carbon • Long dwell time in the sewerage
network
Far-reaching primary treatment of
the wastewater
Industrial wastewater with a high
nitrogen content, e.g. from milk and
meat processing
Nitrogen Low-nitrogen wastewater from:
Paper industry
Fruit and vegetable processing
Phosphorus Landfill leachate, wastewater from
fruit and vegetable processing
www.hach-lange.com
Table 2: Causes and effects of high sulphur concentrations
Profuse development of filamentous
bacteria (sludge bulking and foam)
Insufficient denitrification
High COD/TOC values in the inflow of
the wastewater treatment plant
Filamentous bacteria
Increased COD/TOC values in the
outflow
Filamentous bacteria
If the wastewater in the inflow to the
biological stage is deficient in one of the
main nutrients, a wide range of problems
may occur (Table 3).
For efficient denitrification, a certain
proportion of readily biodegradable C
compounds must be present. After
municipal wastewater has passed
through the primary settling tank, it
has a BOD 5:N ratio of 100:25 (=4). If
the ratio falls below 100:40 (=2.5), the
efficiency of the denitrification process
is impaired, resulting in higher nitrate
values in the outflow. If bypassing the
primary treatment and increasing the
denitrification volume fail to bring about
Causes/Origin of wastewater Possible consequences Corrective action
High concentrations of
sulphur compounds from
chemical and protein
processing industries (meat
and poultry processing)
Anaerobic processes in the
sewerage system, which
cause sulphur compounds
to be reduced to hydrogen
sulphide
Corrosion in sewers and
tank walls in wastewater
treatment plants
Neighbours suffer odour
nuisance
Increased growth of sulphur
oxidising filamentous bacteria
(Type 021 N)
Avoid blockages in the
sewerage network
Add iron salts to the sewer
(e.g. at the pumping stations)
Bypass the primary treatment
Increase the denitrification volume while
retaining sufficient volume for the nitrification
(minimum sludge age of 9 days)
Balance the nutrient ratio by:
Addition of N compounds
(good-value industrial products such as urea)
Addition of domestic wastewater, turbid water
from digester
Balance the nutrient ratio by:
Addition of P compounds (good-value industrial
products such as phosphoric acid or phosphate
fertilisers for the agricultural sector)
Addition of domestic wastewater

NUTRIENTS_MEASUREMENT SOLUTIONS
Optimising nutrient ratios
Measuring station for laboratory analysis
DR 2800 Compact and powerful spectrophotometer with a wavelength spectrum
from 340 to 900 nm for routine analysis and user applications; barcode
reader (IBR) for automatic evaluation of LANGE cuvette tests; backlit
graphic display with touchscreen menu guidance; mains and battery
operated
LT 200 Dry thermostat for standard and special digestions; preprogrammed
digestions for the analysis of COD, total N, total P, TOC, organic acids,
metals
Alternative
HT 200S High-temperature thermostat for fast digestion for the analysis of
COD, total N, total P, metals in just 35 minutes; standard digestions for
analysis of TOC
Cuvette tests Ready-to-use reagents with maximum user safety; highly precise;
approved method; more than 50 parameters and measuring ranges
Systems for online measurement
AMTAX sc Process measuring instrument for continuous determination of the
ammonium concentration in water and wastewater samples with a
low solids content. The measurement is carried out by a gas-sensitive
electrode.
PHOSPHAX sc Process measuring instrument for continuous determination of the
phosphate concentration in water and wastewater samples with a low
solids content. The measurement is carried out using the vanadatemolybdate
method.
NH4D sc ISE ammonium probe for continuous in-fluid determination of the
ammonium concentration. The measurement is carried out using an
ion-selective electrode (ISE) with automatic potassium compensation.
Thanks to the patented closed design (cartridge technology), the
CARTRICAL ® reference system is separated from the surrounding fluid.
NITRATAX sc Process probe for determining the nitrate content directly in water,
wastewater or activated sludge; no sampling required; self-cleaning;
reagent-free method; variety of measuring ranges
SC 1000 Controller A SC 1000 controller system consists of a single LXV402 display module
and one or more LXV400 probe modules. It is configured modularly
to suit the customer’s specific requirements and can be expanded at
any time to include additional measurement locations, sensors, inputs,
outputs and bus interfaces. Each module controls up to eight sensors.
Alternative
SC 100 Controller Controls up to two sensors (not for AMTAX sc or PHOSPHAX sc).
HACH LANGE GMBH
Willstätterstraße 11
D-40549 Düsseldorf
Tel. +49 (0)2 11 5288-320
Fax +49 (0)2 11 5288-210
info@hach-lange.de
www.hach-lange.de
Bestellungen: 0800 208 15 97
Measurement station for laboratory analysis,
with DR 2800 photometer, LT 200 thermostat
and LANGE cuvette tests
Literature
1. ATV-Handbuch: Biologische und
weitergehende Abwasserreinigung,
Ernst & Sohn-Verlag 1997
2. K. Hänel: Biologische
Abwasserreinigung mit
Belebtschlamm, VEB Gustav Fischer
Verlag, 1986
3. K. Mudrack, S. Kunst: Biologie der
Abwasserreinigung, Gustav Fischer
Verlag, 1994
4. Arbeitsblatt DWA A 131
5. S. Kunst, C. Helmer, S.
Knoop: Betriebsprobleme auf
Kläranlagen durch Blähschlamm,
Schwimmschlamm, Schaum,
Springer-Verlag 2000
6. D. Jenkins, M. G. Richard, G. T.
Daigger: Manual on the causes and
control of activated sludge bulking,
foaming, and other solids separation
problems, Lewis Publishers 2004
7. Poster “Operational reliability and
cost saving with HACH LANGE”,
DOC140.52.00449
DOC040.52.10005.May08