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| Date Listed | 08/10/2009
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| Address | Rouse Hill, NSW, Australia
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call 96291568
Waste Water Treatment Plant Consultancy
& On-site Monitoring
* On-site testing of waste water treatment plants for a range of parameters
eg: pH, DO (dissolved oxygen), nutrient levels etc
* Recommendations to improve plant efficiency
* Presentation of written service reports
* Maintenance of plant performance records
Water Testing See Case Study 1
* Grab sampling and analysis of water at various stages of the treatment process
* Autosampling and laboratory analysis of samples collected
* Tabulation of analytical results including graphical presentation
Treatment Chemical Supply See Case Study 2
Aquadynamic Consultancy Services is a licenced distributor of a large range of treatment chemicals for wastewater plants. Such chemicals include:
* Flocculants and polymers
* Bacterial and enzyme treatments
* Nutrients and trace elements
Treatment Plant Recovery See Case Study 2
In the event of a treatment plant upset or overload situation, Aquadynamic Consultancy staff will conduct an on-site assessment and recommend the most appropriate recovery plan.
Treatment Plants / Upgrades See Case Study 3
Aquadynamic Consultancy Services has many years experience in determining the best treatment plant or upgrade to suit your requirements.
Prior to upgrading a plant it is necessary to do a profile of the various ex-factory waste streams (see effluent profiling below)
Effluent Profiling See Case Study 3
Effluent profiling is essential for assessing the pollutant loading associated with the ex-factory waste stream. This involves sampling the waste stream and identifying the type and concentration of pollutants and the hydraulic loading. From this information, Aquadynamic Consultancy Services will determine the most suitable process for treating the waste water.
The Problem: A large cereal manufacturing company had an ongoing problem meeting local metropolitan waste water discharge limits. It was found that suspended solids levels were frequently in breach of licence limits. At times other parameters also exceeded these limits. The Process: (a) Profiling Aquadynamic Consultancy Services profiled the waste water system for a period of three weeks. Autosamplers were installed at various points to collect samples from the three main ex-factory waste streams at hourly intervals. These samples were then tested for suspended solids, BOD, grease and petroleum hydrocarbons. In addition daily water usage was recorded. All results were tabulated and graphed. (b) The Test Results
It was found that the suspended solids from one particular waste stream were frequently in excess of licence limits with regard to both the peak and composite loadings. However the other parameters were within limits most of the time. (c) Bench Scale Trials: Small scale laboratory trials were conducted to determine the best method of suspended solids reduction. Methods trialed included addition of various flocculants and mechanical settling methods. Trial results conclusively showed that an inclined plate separator would be the most effective way to reduce suspended solids in the target waste stream under most conditions. (d) Recommendations: We recommended a suitably sized inclined plate separator be installed to treat the problem waste stream. In addition a DAF (dissolved air flotation) plant was proposed to ensure that this waste stream was compliant with licence limits at all times. Final Outcome: The company implemented the above recommendations, installing a waste water plant which incorporated both a plate separator and a DAF unit. Since this time the treatment plant has functioned well with final effluent meeting licence limits. Ongoing Monitoring and Consultancy : Since the plant upgrade Aquadynamic Consultancy Services has monitored the system regularly, making recommendations and adjustments to plant operation as required.
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Biological Wastewater Treatment
This is a brief summary of the various techniques that have been developed to treat
wastewater by biological means. They accomplish what is generally called secondary
treatment.
Purpose:
The idea behind all biological methods of wastewater treatment is to introduce contact
with bacteria (cells), which feed on the organic materials in the wastewater, thereby
reducing its BOD content. In other words, the purpose of biological treatment is BOD
reduction.
Typically, wastewater enters the treatment plant with a BOD higher than 200 mg/L, but
primary settling has already reduced it to about 150 mg/L by the time it enters the
biological component of the system. It needs to exit with a BOD content no higher than
about 20-30 mg/L, so that after dilution in the nearby receiving water body (river, lake),
the BOD is less than 2-3 mg/L. Thus, the biological treatment needs to accomplish a 6-
fold decrease in BOD.
Principle:
Simple bacteria (cells) eat the organic material present in the wastewater. Through their
metabolism, the organic material is transformed into cellular mass, which is no longer in
solution but can be precipitated at the bottom of a settling tank or retained as slime on
solid surfaces or vegetation in the system. The water exiting the system is then much
clearer than it entered it.
A key factor is the operation of any biological system is an adequate supply of oxygen.
Indeed, cells need not only organic material as food but also oxygen to breathe, just like
humans. Without an adequate supply of oxygen, the biological degradation of the waste
is slowed down, thereby requiring a longer residency time of the water in the system. For
a given flowrate of water to be treated, this translates into a system with a larger volume
and thus taking more space.
Advantages:
Like all biological systems, operation takes place at ambient temperature. There is no
need to heat or cool the water, which saves on energy consumption. Because wastewater
treatment operations take much space, they are located outdoor, and this implies that the
system must be able to operate at seasonally varying temperatures. Cells come in a mix
of many types, and accommodation to a temperature change is simply accomplished by
self adaptation of the cell population.
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Similarly, a change in composition of the organic material (due to people’s changing
activities) leads to a spontaneous change in cell population, with the types best suited to
digest the new material growing in larger numbers than other cell types.
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Types of equipment for biological treatment:
There are two broad types of biological wastewater treatment: those that include
mechanical means to create contact between wastewater, cells and oxygen, and those than
don’t.
a) With mechanical means:
1. Activated sludge: This is the most common type. It consists in a set of two basins. In
the first, air is pumped through perforated pipes at the bottom of the basin, air rises
through the water in the form of many small bubbles. These bubbles accomplish two
things: they provide oxygen form the air to the water and create highly turbulent
conditions that favor intimate contact between cells, the organic material in the water and
oxygen. The second basin is a settling tank, where water flow is made to be very quiet so
that the cellular material may be removed by gravitational settling. Some of the cell
material collected at the bottom is captured and fed back into the first basin to seed the
process. The rest is treated anaerobically (= without oxygen) until it is transformed into a
compost-type material (like soil).
The cost of an activated-sludge system is chiefly due to the energy required to pump air
at high pressure at the bottom of the aerator tank (to overcome the hydrostatic pressure of
the water). Another disadvantage is that the operation is accomplished in two separate
basins, thereby occupying a substantial amount of real estate.
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2. Trickling filter: A trickling filter consists in a bed of fist-size rocks over which the
wastewater is gently sprayed by a rotating arm. Slime (fungi, algae) develops on the rock
surface, growing by intercepting organic material from the water as it trickles down.
Since the water layer passing over the rocks makes thin sheets, there is good contact with
air and cells are effectively oxygenated. Worms and insects living in this “ecosystem”
also contribute to removal of organic material from the water. The slime periodically
slides off the rocks and is collected at the bottom of the system, where it is removed.
Water needs to be trickled several times over the rocks before it is sufficiently cleaned.
Multiple spraying also provides a way to keep the biological slimes from drying out in
hours of low-flow conditions (ex. at night).
Plastic nets are gradually replacing rocks in newer versions of this system,
providing more surface area per volume, thereby reducing the size of the equipment.
3. Biological contactor: This is essentially a variation on the trickling filter, with the
difference being that solid material on which slime grows is brought to the water rather
than water being brought to it. Rotating disks alternate exposure between air and water.
b) Without mechanical means:
The wastewater is made to flow by gravity through a specially constructed wetland.
There, the water is brought into close contact with vegetation (ex. reeds), which acts as a
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biological filter to the water. The organic material in the wastewater is used as nutrient
by the plants. Oxygen supply is passively accomplished by surface aeration (contact with
oxygen of the atmosphere). Since water flow is slow in such system, to give ample time
for the biological activity to take place, there is almost no turbulence in the water and
reaeration is weak.
Compared to mechanical systems, constructed wetlands occupy far more real
estate, but they may be aesthetically pleasing, especially if they are well integrated in the
local landscape. They emit no odor, but people should stay away because of the danger
posed by pathogens. Constructed wetlands have also the least energy requirement.
Energy is only needed to pump the wastewater to the entrance of the system, from where
gravity and biology do the rest. A major disadvantage, however, is the highly reduced
performance during winter, especially in regions where ground freezes during some of
the winter months.
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