CHARACTERISTICS OF WASTEWATER TREATMENT PLANTS AND GENERAL PLANT LAYOUT

:Types of plants

Wastewater treatment plants and processes have been classified as preliminary, primary, secondary, and advanced treatment
A detailed outline of each process is provided in following :

Elements of advanced wastewater treatment

Advanced wastewater treatment encompasses several individual unit operations, used separately or in combination with other processes, to achieve very high overall treatment efficiencies. These processes employ physical, chemical and biological treatment methods.

The objective of advanced wastewater treatment is to improve the removal of suspended solids, organic matter; dissolved solids, and nutrients.
.
1. Polishing ponds. Polishing ponds are used to obtain increased organic and suspended solids removal efficiencies up to 20 percent from existing treatment. Treatment by polishing ponds can be aerobic (the biological activity is predominantly aerobic), or facultative (a combination of aerobic and anaerobic biological
activity).
Polishing ponds are also utilized to allow dissipation of chlorine residual to make discharge compatible with shellfish

2. Post-aeration. Post-aeration applies when a certain effluent dissolved oxygen level must be maintained Post-aeration can be achieved by diffused aeration, mechanical aeration, or cascade aeration
.
3. Microstraining. Microstraining is an effective effluent polishing device for removal of additional
suspended solids and associated biochemical oxygen demand. The process consists of physical straining of solids through a screen with continuous backwashing, utilizing a rotating drum to support the screen. Static screens are also used in particular applications

4. Filtration: Filtration is an effective method for achieving additional suspended solids and biochemical oxygen demand removal following conventional treatment processes. Filtration is also very effective as a part of phosphorus removal systems. Filtration can be applied directly to secondary effluents with or without sedimentation pretreatment by chemical addition

5- Adsorption with activated carbon. The primary function of carbon adsorption as a sewage treatment process is the removal of dissolved organics. This process can be applied as advanced treatment to adsorb non-biodegradable organics, or as a secondary treatment replacing conventional biological
treatment. However, certain organics with small or highly polar molecules (e.g., methanol, formic acid, and
sugars) are not removable by carbon adsorption.
6- Phosphorus removal. The basic phosphorus removal process consists of conversion of polyphosphates to soluble forms and then to insoluble forms, and subsequent separation of the insoluble phosphorus forms from the wastewater accomplished through chemical percipitation using lime or mineral
additives such as alum or ferric chloride.. The process basically involves chemical addition, mixing
flocculation, and sedimentation

7- Nitrogen removal. Methods for removing nitrogen from wastewater include air stripping, biological
treatment, and breakpoint chlorination. Biological nitrification-denitrification appears to be the most practical
alternative in most applications at this time. It involves the biological oxidation of ammonia to nitrate
followed by anaerobic denitrifaction, with nitrogen leaving as nitrogen gas. Nitrification can be accomplished
as a single stage combined with the activated sludge process or as a separate stage. Denitrification is a
separate operation and can be of "suspended growth” or "attached growth” configuration. In this stage,
nitrate is reduced to carbon dioxide, water and nitrogen gas following addition of methanol to provide the
carbon source. Suspended-growth denitrification is an activated sludge-type operation with mixing but
without aeration; attached-growth denitrification is a packed column process with attached biological growth

8- Land application. Land application of secondary treatment effluent can be used effectively as a
means of phosphorous and nitrogen removal, biochemical oxygen demand removal, and solids removal. Since
there is not a direct discharge to a receiving stream, land application in many instances is an attractive
alternative for advanced treatment.

Plant site preparation
Site drainage is an important factor in design of wastewater treatment facilities. Capacities of drainage
structures will be designed in accordance with requirements of TM 5-820/AFM 88-5 series. All treatment
units must be protected from surface rainwater by proper shielding and drainage.

Plant layout
1- Arrangement of treatment units. The first step in determining the best arrangement of units is to arrange all units sequentially according to the flow of wastewater through the system. The resulting hydraulic profile for wastewater flow will determine the relative vertical alignment of each of the plant units. Final
arrangement of the units then results from adaptation of site features to the treatment plant's functional and
hydraulic requirements. Allowance must also be made for the area of operation and maintenance of the
treatment units. If sufficient head is available for gravity flow, the hydraulic requirements will control the
plant layout. Greater flexibility in arranging the treatment plant units is achieved with intermediate pumping of wastewater. The treatment plant must operate during emergency conditions such as power failures and also during periods of maintenance work on treatment units. Dual units should be provided in all feasible
cases to provide operational reliability and flexibility.

2- Conduits and pipelines. Conduits and pipes will be arranged in such a manner as to reduce space
and cost requirements. They will be designed to handle the expected maximum flows through the treatment
plant. Design requirements for pipes and conduits are found in TM 5-814-1/AFM 88-11.
3- Bypasses and overflows. Provisions for bypassing individual treatment units will be made so that each unit can be taken out of service without interrupting the plant operation. Bypasses will not be provided for screen, chlorination units, nor other unit process where duplicate units are available. Overflows will be
used to prevent hydraulic overloading of treatment units, especially biological treatment units. Return of flows or temporary storage of wastes not treated or alternate treatment must be provided. Refer to facility discharge permit for limitations on plant component bypasses and overflows.

4- Future expansion and flexibility. The plant designer will consider provisions for expansion by allowing sufficient space for additional units (and additional conduits) to be installed in the future. The plant will be designed so that installation of additional units or repair of existing units will not disrupt operations

5- Treatment plant discharge. Outfall sewers will be extended to the low-water level of the receiving
body of water or to submergence required by regulatory authority to insure satisfactory dispersion of the plant effluent. Provisions for effluent sampling and monitoring are required. The design will assure the structural integrity of the outfall, prevent failure due to erosion, and prevent back-flow during flooding.TM 5-814-3/AFM 88-11,

: Plant hydraulics
1- Hydraulic loadings. The overall head allowances required for various types of wastewater treatment plant.
2-Limiting velocities. A minimum velocity of 2.0 feet per second at design average flow is required for channel flow. At minimum flows, a minimum velocity of 1.5 feet per second is required to prevent suspended solids from settling in flow channels
3- Head loss. The total head loss through a treatment plant is the sum of head losses in the conveyance of wastewater between elements of the treatment process and the losses of head through treatment units
Head losses from wastewater conveyance are due to frictional losses in conduits, bends and fittings, and allowances for free-fall surface and for future expansions. TM 5-814-1/AFM 88-11, gives detailed guidance and charts for computing head losses in pipes and conduits. Head losses through process equipment
are dependent on the specific units and are specified by their manufacturers or by the design engineer. The design engineer must consider hydraulic constraints in the layout and selection of process equipment and configurations. Special cases where dual and multiple pumping is required must receive prior approval by HQDA (CEEC-EB) WASH DC 20314-1000 for Army projects and HQ USAF/LEEE WASH DC 20332 for
Air Force projects
. Plant auxiliary facilities
1- General, A potable water supply will be provided.
Sanitary facilities: toilet, shower and lavatory with
hot and cold water supply, will be provided except for intallations with less than 0.1 million gallons per day
capacity.
.2- Controls and monitoring. The plant arrangement will take into consideration the related control and
monitoring requirements. Laboratory facilities will be provided for conducting the necessary analytical testing
for the purpose of process control and compliance with regulatory or NPDES requirements.
Essay by
Env.Consult. ahmed elshwadfy
.

Me, Environmental consultant

Environmental consulting is often a form of compliance consulting, in which the consultant ensures that the client maintains an appropriate measure of compliance with environmental regulations. There are many types of environmental consultants, but the two main groups are those who enter the field from the industry side, and those who enter the field from the environmentalist side.
Environmental consultants work in a very wide variety of fields. Whether it be providing Construction Services such as Asbestos Hazard Assessments or Lead Hazard Assessments or conducting due dillgence reports for customers to rid them of possible sanctions. Consultancies may generalise across a wide range of disciplines or specialise in certain areas of environmental consultancy such as waste management.
Environmental consultants usually have an undergraduate degree and sometimes even master's degree in Environmental Engineering, Environmental Science, or some other science discipline. They should have deep knowledge on environmental regulations, which they can advise particular clients in the private industry or public government institutions to help them steer clear of possible fines, legal action or misguided transactions.
Environmental consulting spans a wide spectrum of industry. The most basic industry that environmental consulting remains prominent in is the commercial estate market. Many commercial lenders rely on both small and large environmental firms. Many commercial lenders will not lend monies to borrowers if the property or personal capital does not exceed the worth of the land. If an environmental problem is discovered property owners that deem themselves a responsible party will most likely reserve monies in escrow in order to resolve the environmental impact.
With increasing numbers of construction, agriculture, and scientific companies employing environmental consultancies, the industry can expect growth in the vicinity of 9.7 percent in 2008, amidst mounting public concern over environmental degradation and climate change. And while some companies are genuinely motivated by concern for the environment, for others, hiring consultants to appear to be "going green" has proven to be a useful marketing tool. Growing government funding into renewable energy and technologies producing low emissions is also helping growth, as organizations investing in research and development in these areas are often major employers of environmental consultants[1
Environmental consultant: Ahmed
I chose this career as I have always enjoyed being outdoors and being an environmental consultant involves both office and site-based work.
As an environmental consultant in the field of contaminated land I spend about 50% of my time in the office and 50% on site. Site works consists of the excavation of trial pits and bore holes to assess ground conditions, but can also include building surveys. The work I do in the office involves factual and interpretive report writing for contaminated land and radiological surveys, along with assessment of laboratory data against environmental standards and risk to human health.
I found the job through a recruitment agency that specialises in environmental positions. They were asking for one year's relevant experience and a degree in a science subject.
I gained a lot of relevant skills and experience from my degree for work within environmental consultancy. I gained an appreciation for field work and the basic logging techniques which are used for site excavations, and the ability to interpret and discuss scientific reports. I also developed an understanding of geology and the appreciation of varying characteristics of strata and how they can impact on contamination.
Since I have been a consultant, my role has developed and I have been given more responsibility in the submission of interpretive reports and the development of proposals to meet clients' requirements and objectives. I really enjoy every part of my job, getting particular satisfaction from being on site, meeting clients and problem solving, which requires quick thinking due to the limiting time factor. I also really enjoy interpreting scientific data for comparison against human health risks and environmental baseline standards.
It's too early in my career to pinpoint which area of consultancy I wish to specialise in, but I am currently enjoying learning within the contaminated land area. However I would also like to develop within human health.

Environmental consultant: Job description and activities

Environmental consultant: Job description and activities
1. Job description
2. Typical work activities
Job description
An environmental consultant works on commercial contracts to address a variety of environmental issues for their clients. They cover a wide range of disciplines such as assessment of air, land and water contamination, environmental impact assessment, environmental audit, waste management, development of environmental policy and development of environmental management systems.
The sector continues to expand in response to a mix of regulation, corporate risk and reputation management. Consultants operate in a very commercial environment and senior staff may be required to help attract future clients for the business.
According to the 2008 Environmental Data Services (ENDS) survey of environmental professionals, the majority continue to be employed in the consultancy sector.
A career as an environmental consultant offers the opportunity to work on a variety of different disciplines, with the potential to specialise.
Typical work activities
As there is such a variety in the type of work that an environmental consultant may undertake on a day-to-day basis there is clearly a wide range of typical activities. A key task is to identify whether land, air or water is contaminated by means of desk-based research and field work, and then undertake an assessment to identify if that contaminant source can have an adverse impact on a receptor (such as humans or groundwater, for example).
Typical work activities include:
 Conducting field surveys: collecting data to establish a baseline condition for levels of pollution or contamination for a site or area of consideration.
 Data interpretation: this can include detailed assessment of data, often using software modelling packages, to identify whether 'contamination' exists in accordance with legislative drivers.
 Development of conceptual models: this involves identification and consideration of the potential contaminant sources, critical pathways and receptors that could potentially have an adverse impact on the immediate and wider environment.
 Report writing: completion of detailed scientific reporting, written in a manner that can be understood by non-technical people.
 Dialogue with clients, regulators and sub-contractors e.g. analytical laboratories.
 Due diligence: carrying out desk-based research to review previous investigations of a site that a client wants to purchase, and possibly undertaking field work, to identify previous activities on the site and any contamination.

waste water treatment plant design

1-Introduction

Oil industry represents an important part of the food industry.A large number of disposes of their wastes into the environment in enormous quantities,constituting a significant loss of resources and causing serious pollution problems.If any saving in energy waste can be coupled with a cheap form of waste utilization or treatment,it would further improve the benefits to the food industry.

In the activated sludge plant, the water to be treated is subject to the simultaneous contact with microorganisms and oxygen (air). These microorganisms convert the organic compounds in the raw water for the greater part into carbon dioxide,water ammonia and new activated sludge.
the carbon dioxide generated is released into the atmosphere by aeration.The organic compounds are partly converted into micro-organisms,whilst the over-crowd is disposed off as excess sludge.
Because of long standing aeration,the ammonia formed by the activated sludge will be converted into nitrite, and after that into nitrate(this process is called nitrification).
Total nitrogen-reduction is requird by denitrification process, and it takes place under anoxic circumstance and uses the carbon in the wastewater to convert nitrite and nitrate into nitrogen gas, and it is released into the atmosphere.

2-System Information
Here is the information needed for waste water treatment plant design.
2.1 design parameters
The design of the system quoted here is based information obtained from client and experience.The client should inform us, if he feel that the design parameters, listed below, do not reflect actual situation:

*Type of wastewater
Wastewater from oil industry
* Quantity of wastewater
Plant design capacity,
Max=30 m3/day

*physical-Chemical constituents of wastewater

*For Sedimentation/Flotation System
-Water temperature:30 c
-PH:8.4
-COD:1400 mg/l
-BOD: 720mg/l
-SS:714 mg/l
-Nitrogen Total: 21.6 mg/l
-Oil& grease:-- mg/l

Above mentioned figures for COD,BOD,TKN,and SS are estimated related to our experience with similar processing plants.

2.2.System Design

Calculations of elalameah for oils


Background...
Abbreviations...
Q (m3 / h)
Flow - rate
Qo (m3 / h)
Influent flow - rate
Qe (m3 / h)
Effluent flow - rate
Qr (m3 / h)
Recycled sludge flow - rate
Qw (m3 / h)
Wasted sludge flow - rate
BOD (mg / L)
Biochemical oxygen demand
BODo (mg / L)
Influent biochemical oxygen demand
Va (m3)
Aeration tank volume
SS (mg / L)
Suspended solids (SS)
SSe (mg / L)
Effluent SS
SSr , w (mg / L)
Recycled and wasted sludge SS
A (m3 / h)
Air flow - rate
MLSS (mg / L)
Mixed liquor suspended solids
t (h)
Hydraulic retention time
OL (kg BOD / m3 . day)
Organic loading
F / M (kg BOD / kg MLSS . day)
Food to microorganism ratio
r
Recycle ratio
SA (day)
Sludge age
ASR (m3 / kg BOD)
Air supply rate
E (%)
BOD removal efficiency
Equations...
(1) Normally ;Qw << Qo and Qe = Qo = Q(2) Aeration time or hydralic retention time = Volume / Flow - ratet = Va / QTypical aeration times : Conventional activated sludge process = 4 - 8 hrs ; Contact - Stabilization = 0.5 - 1.0 hrs (contact tank) ; Extended aeration = 24 hrs (aeration times are used to determine volume of aeration tanks)(3) BOD or organic loading = Mass of BOD applied per day / Tank volumeOL = ( Qo )( BODo ) / VaTypical OL values : Conventional activated sludge process = 0.3 - 0.6 kg BOD / m3 . day ; Contact - Stabilization = 1.0 - 1.2 kg BOD / m3 . day ; Extended aeration = 0.16 - 0.4 kg BOD / m3 . day (this is an alternative method for determining volume)(4) Food to microorganism ratio = Mass of BOD applied per day / Mass of suspended solids in aeration tankF / M = ( Qo )( BODo ) / ( Va ) ( MLSS )Typical F / M values : Conventional activated sludge process = 0.2 - 0.4 kg BOD / kg MLSS . day ; Contact - Stabilization = 0.2 - 0.6 kg BOD / kg MLSS . day ; Extended aeration = 0.05 - 0.15 kg BOD / kg MLSS . day (used to determine the needed concentration of MLSS)(5) Recycle ratio = Recycle flow - rate / Influent flow - rater = Qr / QoTypical recycle ratio values : Conventional activated sludge process = 0.25 - 0.50 ; Contact - Stabilization = 0.25 - 1.0 ; Extended aeration = 0.75 - 1.5 (used to control concentration of MLSS)(6) Mean cell residence time or sludge age = Mass of suspended solids in aeration tank / Mass of solids leaving the systemSA = [ ( Va )( MLSS ) ] / [ ( Qe ) ( SSe ) + ( Qw ) ( SSw ) ]Typical sludge age values : Conventional activated sludge process = 4 - 15 day ; Extended aeration = 20 - 30 day (an estimate of the length of time that average suspended solids or biomass stays in the process, used to select volume and MLSS and solids wasting rate)(7) Air supply rate = Volume of air per unit time / Influent flowASR = A / QoorASR = A / [ ( Qo ) ( BODo ) ](8) BOD removal efficiency ;E ( % ) = [ ( BODo - BODe ) / BODo ] 100 (BOD removal efficiency is a function of MLSS, sludge age, or F/M ; there is usually an optimum range of MLSS, sludge age, and F/M)
Basic Calculations...

Treatment Efficiency
90%
Design of the Activated Sludge Process
Influent wastewater flow = 30m^3/day,
Volume of aeration tanks = 72 m3,
Influent total solids (TS) = mg / L
Influent suspended solids (SS) = 714 mg / L,
Influent BOD = 720 mg / L,
Effluent TS = mg / L,
Effluent SS = mg / L,
Effluent BOD =1oo mg / L,
MLSS = 2,500 mg/L,
Recirculated sludge flow = mgd,
Waste sludge flow = mgd,
SS in waste sludge = mg/L.
Calculation:

(a) Aeration period = Volume / Flow without recirculation =
26 m3 / 30 m3 / day = .8 day = 20 hr
(b) BOD organic loading
Ol=Q*BOD/V
=30 m3/day*720)/ 26
=8,3 mgBOD/m3
=.08 Kg BOD /m3
(c) F to M = Quantity of influent BOD / Mass of MLSS in Aeration BasinF to M = [(720 mg / L) (8.34 mg / m3 / mg / L) (30 m3/day)] / [(2,500 mg / L) (8.34 mg / m3 / mg /L) (30m3/day)] = 0.28 mg BOD / mg MLSS
(f) BOD removal efficiency = (720 - 100) / 720 = 87 %
(g) Sludge age = [(MLSS) (Volume)] / [(SSe) (Qe) + (SSw) (Qw)]Sludge age = [(2,500 mg / L) (30 m3/day) (8.34 mg / m3/ mg / L)] / [(22 mg / L) (30 m3 / day) (8.34 mg / m3 / mg / L) + (9,800 mg / L) (0.054 mil.gal / day) (8.34 lb / mil.gal / mg / L)] = 8.0 day
(h) calculating aeration tank volume
F/M=Q*BOD5/v*MLVSS
0.28=30*720/V*3000
V=26 m3
With surface area= 3*4
Depth= 2.5 m and the excess is not effective area

(j) calculating retention time at aeration tank
HRT=V/Q*24
=26/30*24
=20 hr
=,8 day

(h) calculating quantity of oxygen needed
=1.5*mg BOD5
=1.5*720
=1080 mg O/l


Calculations of sedimentation tank

Considering detention time =4 hrs
Volume=12 m3
Surface area=12/2=6 m2
= pi D2

Diameter^2=area/3,14
=6/3.14
=1.9 m
So let the diameter of settling tank be 2 meter

2.3 plant performance
Based on the given design data and our experience with similar wastewater we expected to meet your effluent requirements.
PH:6.5-7.5
Bod: 100mg/l
COD: mg/l
SS: mg/l
TN:<50mg/l
oil&grease:--mg/l
sulfite:<1mg/l
phosphorus:<5mg/l

the treated water compliance with environmental laws for discharged to sewer.
By ahmed elsayed elshwadfy
Environment and safety consulatant