Name: Aiden Cavallero

Student Number: 13011423

Course: Chemical Engineering, 3rd Year

Employer: Cassowary Coast Regional Council

Period: 7th December 2015 to 19th February 2016

IntroductionFrom the 7th December 2015 to the 19th February 2016, I was employed for 11 weeks by the

Cassowary Coast Regional Council to work with both operators and engineers at a number of

water and wastewater treatment plants dotted throughout the region.

During the course of my placement, I was involved in the completion of many tasks that

demonstrated the importance of such an industry in the maintenance of clean drinking water.

Through the completion of these tasks, I was also made aware of many environmental, social

and economic factors that can impact on this industry as well as the effects these can have.

Environmental impacts can be in the form of continuing drought or heavy rainfall events, in

which the incoming flow to these plants may be too great or too little for correct operation or

even contain undesired quantities of certain substances. In these cases, costs associated with

the necessary increased usage of resources and chemicals for treatment can lead to both social

and economic impacts, in the form of increased chemical concentrations in water effluent and

also higher water prices to the public to fund these increases. In addition, water restrictions

may also have to be put in place if there are certain chemicals found to be in the water supply

or if there is only a limited amount of water in the creeks and reservoirs. In this way there is a

necessary balance between the costs of operation of these plants and the final quality of the

water consumed by the public.

I worked directly with the operators at the Tully and Innisfail Activated Sludge Wastewater

Treatment Plants, the Innisfail Water Treatment Plant, and also the coordinator of all water

treatment throughout the region, Shane Bandiera. In addition to this, I was also given the

opportunity to work with agricultural engineer Matthew Driver, who was able to provide me

with invaluable insight to assist me in the completion of various tasks.

Tasks & Duties PerformedDuring my 11 weeks at the Cassowary Coast Regional Council (CCRC) I was allocated the

following tasks:

1. Familiarisation with Treatment Processes

Throughout the duration of my placement at each of these plants, I was required to complete

many duties that involved a thorough understanding of each of the treatment processes. To

be effective in this area it was therefore necessary to familiarise myself with these processes

and this continued throughout my entire placement as each new task came to my attention.

Initial preparation for this involved discussing the process with the operators, often while

collecting samples at various points in the process. This preparation then continued as I

sought literature from each plant to gain a deeper understanding of the mechanical, chemical

and biological aspects involved. For both the Tully and Innisfail Wastewater Treatment

Plants, this came in the form of the book “Practical Guide to the Operation and Optimisation

of Activated Sludge Wastewater Treatment Plants” written by Brice and Mosse of the Water

Industry Organisation of Australia, which described these properties in detail and reinforced

the information provided by the operators. From these sources, I was then able to sketch a

diagram of flows through the plants and detail any chemical reactions taking place (see

Appendices A&B).

In order to further understand the process at the Innisfail Water Treatment Plant it was

necessary to read the internal summary of the process written by Edgerton & McKenzie.

This summary provided the optimal set-points for the process and in addition gave a

schematic of the plant with average flow rates and necessary pressures, further allowing me

to understand the mechanical aspects of the process. From this information I was then able to

sketch a flow diagram of the water through the plant (see Appendix C).

2. Familiarisation with Software

Once familiar with the overall operation of the treatment plants, I was required to familiarise

myself with the usage of several software programs including Citect Supervisory Control &

Data Acquisition (SCADA) and SWIMLocal.

For the task of familiarising myself on the usage of the Citect SCADA control system, it was

first necessary to discuss this software with the operators at the Innisfail Wastewater

Treatment Plant (IWWTP). From this discussion I was able to gain a basic understanding of

the software and its components, which I was then able to build upon through everyday

operations. In addition to this, I was granted access to the SCADA manuals for each plant,

which detailed all operations contained in the software and also contained a glossary for any

alarms and faults that may occur. With this information I was able to become competent in

the use of the software, therefore enabling me to detect undesirable changes in the plants and

notify the operators in advance.

The other major software that I was required to familiarise myself with was SWIMLocal, a

new QLD government initiative designed to improve the communication of reports and test

results between water treatment plants and the state government. For this software, there was

no information readily available, and therefore it was necessary for me to learn through trial

and error. Throughout this process I was also assisted by Shane and Matthew who were able

to provide me with the location of the data to be entered, and thus I was able to utilise the

software to communicate to the government the complete suite of results for all testing of

2015. In addition to this, I was also required to complete a report containing a summary of

both the advantages and disadvantages of the software and submit this to Shane, who would

then use this to decide if the software would be implemented in its entirety at all plants

3. Tully and Innisfail Water & Wastewater Treatment Plant Operations

Once I had become familiar with both the treatment processes and the software utilised by

these treatment plants, I was able to complete everyday operations of these plants and also

engage in consultations with both contractors and consultants in the industry.

The everyday tasks and operations of the plant were mainly those dictated by the regulations

placed on the treatment plants to meet license requirements issued by the Department of

Environment and Heritage Protection (EHP). These licenses are currently in place to regulate

the chemical concentrations that can be released to the receiving body of water, and as a

result regular testing was conducted on the influent, reactor, clarifiers and also the effluent to

ensure these requirements were met. I was thus involved in both the gathering of samples

and lab testing, and in the cases of irregular concentrations being discovered, I discussed

possible causes and solutions with the operators before exceedance occurred.

In the cases where higher concentrations were detected, I was then involved in the creation of

a solution to reduce these to a manageable level. One such example of this occurred when the

dissolved oxygen (D.O) probe in the aerobic reactor of the IWWTP was unable to connect to

SCADA, and thus the aerators responsible for the maintaining of the D.O level were unable

to run on an automatic setting. In addition to this, the manual settings on the aerators were

measured in motor percentages at hourly intervals, and being that there was no link between

these percentages and the D.O level, trial and error methods were used. These methods

involved the observation of historical data of the motor speeds of the aerators at different

times, and also the use of a handheld D.O probe to create a profile of the D.O levels around

the reactor at regular intervals, and this was a process in which I was directly involved. From

this, the motor speeds of the aerators were therefore able to be set with a larger degree of

accuracy,

In addition to chemical concentration exceedances, there were also issues that arose that were

unable to be solved by the operators and, as a result, external assistance was required. This

assistance was provided by contractors, tradesmen, industry consultants and engineers, and

thus I was asked to discuss with them and, where possible, participate in their solutions.

From this participation, I was able to learn a broad range of skills that I continually used

throughout my placement at all plants for both practical purposes and also for theoretical

discussions with the operators.

4. Chemical testing of unknown substance

One extra task that I was required to complete during my time at the IWWTP was the

analytical testing of an unknown substance which had been stained onto a bench more then

12 months prior. After first discussing this with the operators, I found that they believed this

substance to be a crystallised 25% w/v solution of Aluminium Sulphate from the plant’s

supply. Upon first observations of the crystals, I found them to have the characteristic white,

powdery shape of a sulphate, and thus decided to conduct chemical testing to confirm their

identity.

For my initial test, I decided to conduct a pH test to confirm the acidity of the crystal

solution. For this I used Phenol Red indicator in tap water as a reference and compared this

to the colour of the crystal solution upon addition of the same indicator. From the yellow

coloration of the solution compared to the orange/red coloration of the reference, it was

proven that the crystal came from an acidic substance. I then researched a test for sulfates,

and found that the most reliable test, that of the addition of HCl and BaCl to the Metal-SO4-

solution to create BaSO4 crystals, was unable to be carried out with the laboratory materials

on hand. In order to carry out this test then, I substituted the BaCl with NaCl, and the HCl

with Sodium Hypochlorite to maintain the balance of Cl- ions. After leaving the mixed

solution in the oven for a period of time, a mass of long, thin white crystals then formed

which confirmed the presence of sulfate ions in the crystal solution. Based on these results

and the fact that the only acidic sulphate on hand at the treatment plant was AlSO4, I was able

to deduce that this was in fact the stain on the bench, confirming the operator’s beliefs.

ReflectionThis placement provided an invaluably broad understanding of not only the process involved

with the treatment of water and wastewater, but also the work performed by all parties

concerning the economic, environmental and social outcomes of such a plant.

Throughout my 11 weeks of placement I was able to learn about and apply my own

knowledge to the biological and chemical processes involved in the basis of every activated

sludge wastewater treatment plant operation. I was also able to learn about the different

stages of both water and wastewater treatment, and while sampling and testing this water I

constantly discussed with operators possible reasons for any irregular values that were

discovered and solutions to these problems. In doing this then, I was also made aware of

many challenges that may face an engineer in the industry, including managerial,

organisational and also the achievement of sustainability. From my experience at the CCRC,

these challenges centre mainly on the required forethought when constructing a plant, and

thus preparing for any event that may occur. For this process to be effective then, it was

made clear to me that discussions must be had with all parties concerned, and in particular the

operators responsible for the everyday operation of the plant itself. With this in mind,

contingency plans must be applied containing details of all costs involved, the impact on the

local community, and also the final acceptable quality of the water. Once this has been

achieved, the project will not proceed until all parties are accepting of the plans, at which

point teamwork and organisation are the main factors for success. Thus, ideally,

sustainability has been achieved and problems have been solved before they occur.

ConclusionDuring my 11 weeks at the Cassowary Coast Regional Council I believe I have gained an

invaluable practical experience. Through the tasks I have completed I have developed a great

understanding regarding the chemical processes of water and wastewater treatment, and, in

doing so, have reinforced my own knowledge of both chemistry and process engineering. In

addition to this, I have also learnt a great amount about the role of engineers in such an

industry and the responsibilities they have to both the public and the environment.

I have thoroughly enjoyed working in my position with the entirety of the CCRC for the

better part of three months, and in particular I would like to thank Glen Campbell and Tony

Bowater, the operators at the Innisfail Wastewater Treatment Plant; Damian McKenzie and

Tyler Edgerton, the operators at the Innisfail Water Treatment Plant; Bob Barratt, Hamish

Crawford and Michael Mills, the operators at the Tully Wastewater Treatment Plant, and also

Shane Bandiera, for providing me with this opportunity.

Appendix A – Process Outline for Innisfail Wastewater Treatment Plant

Appendices

Appendix B – Process Outline for Tully Wastewater Treatment Plant

Appendix C – Process Outline for Innisfail Water Treatment Plant

Appendix D – Reactions present in Wastewater Treatment Plants

Reaction for the addition of aluminium sulphate to solution:

Al2(SO4)3 + PO42- Al2(PO4)3 + SO4

2-

Reactions taking place in the Aerobic Zone – Nitrification

2NH4+ + 3O2 4H+ + 2NO2

- + 2H2O --- Nitrosomonous Bacteria

2NO2- + O2 2NO3

- --- Nitrobacter Bacteria

These reactions are carried out by Chemolithoautotrophic Bacteria through the consumption of alkalinity supplied by the NaOH/CaCO3.

Reactions taking place in the Anoxic Zone – Denitrification

2NO2- + 2H+ 2NO + 2H2O

2NO3- + 2H+ + NO 3NO2 + H2O

3NO N2O + NO2

2N2O 2NO + N2

N2 + O2 2NO

Reactions are catalysed by various forms of facultative bacteria (e.g. Pseudomonas) that require energy in the form of organic material. An additional by-product of this process is Carbon Dioxide