enhanced biological treatment and sludge management for ... conference... · circuiting/high flows,...

Enhanced Biological Treatment and Sludge Management for Wastewater Lagoon Optimization

2019 TSAG WATER CONFERENCE

OCTOBER 23RD, 2019

Presented by:

Christine GanBishop Water Technologies

[email protected]

Why upgrade your lagoon?

“Now” reasons:

• Not meeting discharge limits • Performance has reduced over

time • Limited efficacy during cold

weather conditions or peak flows

“Later” reasons:

• Anticipated population growth/higher loads

• Municipal development →industrial effluents

• Increase robustness to “get ahead” of more stringent discharge limits to come

The “why” can matter when considering different solutions!


For example:

Challenge: Overall reduced lagoon performance over time

Potential causes:

1. Sludge accumulation (benthal feedback)

→Benthal feedback in ponds can leadto high effluent concentrations ofTSS, BOD and nutrients


For example:

Challenge: Overall reduced lagoon performance over time

Potential causes:

1. Sludge accumulation (benthal feedback)

2. Changes in wastewater characteristics or environmental conditions (pH, dissolved oxygen levels, temperature etc.)

3. Reduced bacterial activity due to washout/short circuiting/high flows, algae growth


Sludge accumulation (benthal feedback)• Dredging operation/lagoon cleanout • Pre-screening or larger settling pond

Changes in wastewater characteristics• Aeration, pre-screening• Implementation of attached-growth systems

Reduced bacterial activity• Baffles to redirect flow and increase hydraulic

retention time (HRT)• Aeration for better mixing • Implementation of attached-growth systems

The BioCord Reactor for Lagoon Optimization and Improved Nutrient Reductions

Locating where the issue lies

The importance of lagoon profiling and comprehensive data collection

Where is the problem?

When it’s not immediately obvious (e.g. you can see where algae grows), profiling your lagoon will tell you where the problem lies and/or where you need to focus treatment

1 2

3 4 5

= sample point

Influent

Effluent

• Plant influent + effluent• Wet well chambers to

each lagoon

Pond 2Pond 1

Example: Western Canadian facilityConcern: Effluent ammonia

Raw Influent

NH3: 40-50 mg/LBOD: 27 mg/LTSS: 50 mg/LDO: 6.2 mg/LpH: 7.6

Final Effluent

NH3: 25-30 mg/L (winter)6-9 mg/L (summer)BOD: 10-15 mg/LTSS: 20 mg/LDO: 7.7 mg/LpH: 8.0

Anaerobic lagoon Anaerobic lagoon

Aerobic lagoon (Pond 3)

Centre berm for increased HRT

SolarBee toincrease mixing

62 aerators (640 SCFM)

• No significant algae growth visible

Pond 2Pond 1


Raw Influent

NH3: 40-50 mg/LBOD: 37 mg/LTSS: 50 mg/LDO: 6.2 mg/LpH: 7.6

Final Effluent

NH3: 25-30 mg/L (winter)6-9 mg/L (summer)BOD: 10-15 mg/LTSS: 20 mg/LDO: 7.7 mg/LpH: 8.0


Pond 1 Effluent

NH3: 35 mg/LBOD: 117 mg/LTSS: 48 mg/LDO: 0.6 mg/LpH: 7.1

Pond 2 Effluent

NH3: 35 mg/LBOD: 134 mg/LTSS: 65 mg/LDO: 0.7 mg/LpH: 7.1

High BOD entering aerobic lagoon contributes to inhibition of nitrifier growth

Pond 2Pond 1



Solution:

•Dredge Pond 1, Pond 2

•Upgrade Pond 1 or Pond 2 to more efficiently reduce BOD

Addressing Reduced Performance in Lagoons

Upgrading lagoon systems for increased treatment, prevention of algae, and better

cold-weather performance

Now that we’ve identified what’s wrong …

How can we address the problem?

1) Upgrade capacity and robustness of lagoons

2) Sludge removal

3) Alternatives: chemical dosing, beneficial bacteria, controlled discharge

• Increase microbial content & activity, oxygen, mixing, SRT

Solution #1: Upgrade capacity and robustness of lagoons using biofilm

The most effective and cost-friendly way to upgrade a lagoon is using an attached growth system to increase capacity

Using the BioCord Reactor as an example, this presentation will outline:

•How they work and benefits to an attached growth system

• What issues will it resolve?

•Considerations and differentiators

•Improving cold-weather treatment

•Optimization of biological processes

BioCordTM Reactors: An Overview

• Attached growth system for lagoons and basins

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Provides optimal conditions for beneficial bacteria to develop and treat WW:

✓ High surface area ✓ Charged surface for stronger

microbial attachment✓ Enhanced oxygen delivery and

mixing


The creation of an optimal environment leads to the rapid proliferation of microorganisms to form robust and stable biofilm

• Significantly higher concentration and activity of bacteria that treat wastewater (utilize nutrients faster than algae)

• Bacteria are fixed to the media surface, which increases SRT and prevents washout at high flow rates

Biofilm develops in layers, creating microclimates that form a heterogeneous microbial population

• Heterotrophs and nitrifiers can co-exist

• Biofilms can contain both aerobic and anaerobic environments

• Dissolved nutrients can diffuse into inner layers during colder temperatures (insulation provides warmth)


Clean Media

Media covered in biofilm

(microorganisms)


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• The biofilm does not die off under shock loads, but is able to “bounce back” from stress conditions and treat atypical wastewaters

• BioCord Reactors are a dynamic, living system that will respond and acclimatize to the conditions they are exposed to

Attached growth systems: What’s the difference?

• Performance

• Oxygen delivery/efficacy

• Cold weather performance

• Cost, energy usage

• Scalability and retrofit capabilities

• Maintenance and operation

• Client support and customizability

1. Oxygen delivery/transfer efficiency

• Oxygen delivery and utilization is crucial in biological wastewater treatment and attached growth systems (recall reactions)

• Aeration is often the most expensive aspect of WW treatment• Higher oxygen transfer efficiency (OTE) = better performance and treatment (increased

mixing, healthier biofilm), lower energy requirement

Energy + cost

Performance

Pressurized microbubbles =

• BioCord Reactors have an integrated aeration system underneath each unit

• Fine bubble tube diffusers use pressurized air (compressors) to deliver microbubbles, which are more efficient at increasing DO using lower energy

Pressurized fine bubbles can also help contribute to:

•Better mixing•contact/diffusion into the biofilm layers•better wastewater-microbe contact (less

short circuiting)•helps prevent algae growth

•Biofilm sloughing and self-maintenance

•Prevention of clogs in the diffuser

Enhanced Oxygen Delivery using Bubble Tubing

Fouled biofilm due to poor mixing, uneven oxygen delivery

Additional benefits of BioCord’s integrated aeration system:

•Increased cold-weather performance

•Compressors provides insulating effect

•Mixes warmer water from bottom layers with upper layers

•Pressurized bubbles keep water open

Enhanced Oxygen Delivery using Bubble Tubing

Average water temp: 6.9 oCLowest water temp: 2.8 oC

BioCord average % reduction: 67%

Pond 2 (control) average % reduction: 2%

Cold-weather nitrification using BioCordTM

Pilot project in a city in Central Western Canada:

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Cost and energy usage

• In general, lower initial capital costs compared to MBBR, MABR systems• Significant operational cost savings compared to traditional blowers for

treatment

• e.g. Membrane bioreactors (MBR) can reduce footprint requirement, but are very cost and energy intensive

• Some systems prone to clogging, need more maintenance and/or control

Cost/energy usage, O&M costs Footprint/scalability

Pressurized microbubbles in BioCord Reactors help prevent clogging. Operational costs are saved with technologies that require little operator oversight and training.

o Membrane replacement every ~8 yrs

• Modular systems preferential for scalability

• Technologies that can be retrofit into existing basins/be installed in-situ have minimal footprints + decreased capital

• Customizable for specific WW characteristics

Optimizing Attached Growth Systems

Location, piloting, troubleshooting

Where will I install an attached growth system?

•Can be placed virtually anywhere in a lagoon system, but some are better than others

•Depends on treatment targets

BOD

Use as polishing to get lowest concentrations in effluent

Ammonia

Highest ammonia, lowest BOD area

BOD + ammonia

Highest ammonia, lowest BOD

• Two locations may be optimal

•For a biofilm to remain robust and proliferating, it needs to be provided with a consistent supply of “food” (ammonia or carbon)

•Concentrations should not be <5 ppm for extended periods of time

•Try and avoid areas that see large fluctuations in characteristics


•High levels of TSS (>100-200 mg/L) or debris is the most common detriment to biofilm

•Solids clog a biofilm and contribute to fouling (decreased surface area, decreased oxygen diffusion)

•Choose an area with low TSS


•Toxic influents from industrial discharge will inhibit microbial activity

•Look at COD:BOD ratio in influent for clues


Solution 2: Sludge removal via Lagoon cleanout/dredging

When and where?

•Proper monitoring program will give you an idea of where sludge accumulation may be prevalent

•Also: sludge mapping/surveying

Determining sludge thickness

Taken from http://www.triplepointwater.com

Sludge surveying methods

Secchi disk

Sonar depth finder

Infrared sensor Sludge judging (PVC pipe with a flap foot valve)

Sludge surveying methods

• Sludge accumulates unevenly • influent area, wind, flow, aeration

• 12-36 measurements around lagoon based on size

Analyzing your data

• Calculate sludge volume and treatment volume

•Multiple online resources to help

• Sludge Data Sheet and Volume Calculator from The North Carolina Department of Agriculture and Consumer Services

http://www.triplepointwater.com/wp-content/uploads/2015/06/Sludge-Data-Sheet-and-Volume-Calculator.xlsx

Sludge removal

•Wet dredging

•Dry dredging

•Mechanical dewatering and hauling

•Onsite dewatering

Mechanical vs Onsite Dewatering

Mechanical dewatering:

•Reduces weight by >90%

•Can be expensive

•Requires polymer addition

Onsite dewatering:

•Less expensive

•Require land

•Requires polymer addition

Other considerations for lagoon cleanouts

•Sludge concentrations/solids content

•Polymer conditioning/flocculating the material

•Optimizing chemical dosing

•Jar testing

•Land application potential

•Costs and energy usage

Geotube® units for solids management and dewatering

• Custom-fabricated geotextile containers for dewatering • Patented seaming techniques and fittings that withstand pressure

during pumping operations• High flow rate allows residual materials to dewater rapidly, while

containing solids

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Step 1:Filling/Containment

Dewatering process using Geotube® units

Step 2: Dewatering

Step 3: Consolidation

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Advantages for solids management using Geotube®

• Handles a variety of materials

• Minimal permitting required

• Dewatered material can be easily disposed or additional value captured

• Passive dewatering = Low Energy Use

42

Energy usage & GHG emissions

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Case study: Perth

Our carbon calculator performs a detailed analysis of lifecycle carbon emissions and helps to quantify environmental impact

Alternative solutions:Targeted phosphorus removal, beneficial bacteria, and more

Chemical dosing

•If high effluent phosphorus is a problem, chemical dosing may be required for complete removal

•Bio-P removal is complex as microorganisms don’t remove P, only cycle it

•P must be removed through sedimentation or precipitation

Chemical dosing – P removal

Aluminum salts

Chemical dosing – P removal

Iron salts

Introducing RE300: Improved Phosphorus Removal using Rare Earth Metals

Bishop Water is very excited to have recently become themain distributors for RE300, a rare earth salt solution thateffectively removes Phosphorus to levels less than 0.07

mg/L.

Developed by NEO Water Technologies, RE300 rapidly andstably precipitates phosphorus in municipal andindustrial/municipal wastewater facilities, and has beensuccessfully used in over 50 facilities in the US.

A molar ratio of only 1:1 RE:PO4 is needed for maximumremoval of phosphorus.

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RE300 - How does it work?

Rare Earth salts - Lanthanum and Cerium

• Exist naturally in mineral complexes, preferentially to phosphorus• RE300 salt solution targets P to create a dense, insoluble precipitate that rapidly

settles out of solution

RE300 creates a stronger bond to P than ferric or alum, meaning less chemical is needed and less sludge is produced

Forms rhabdophane precipitate via a strong crystalline ionic bond(RE3+ + PO43‐ → REPO4∙H2O)

Form amorphous “cloud” in solution which only adsorbs P onto floc

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RE300 Iron and alum-based products

Benefits and

Advantages

• Achieves < 0.07 ppm-P with no added capital equipment,

e.g. tertiary filters

• Achieves 1:1 molar ratio of RE:PO4

→ Reduced chemical sludge

• Improves coagulation and dewatering in filter presses and

centrifuges

• -40oC freezing point: no need for heated storage and pipe

tracing

• Inhibits struvite build-up and improves water clarity

• Does not affect pH: no pH adjustment necessary

• Will not stain or discolor facility structures or equipment

• Is non-hazardous and safer to work with than Fe- and

aluminum-based products

• Can be applied in primary, secondary, and tertiary treatment

• Municipal plants using RE300 have repeatedly passed whole

effluent toxicity testing at 100% effluent concentration

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Beneficial bacteria

•Lagoons can be bioaugmented using dosages of beneficial bacteria to help break down stubborn contaminants and accelerate decomposition

•Bacteria, micronutrients, enzymes, and stimulants

•High BOD, FOGs, nutrients, odours etc. • E.g. meat processing plants

Beneficial bacteria

•Can be expensive

•Requires consistent dosing as bacteria wash out

•Requires aeration for optimal performance

•Recommended for use during seeding (start-up) or recovery from toxic event, not recommended as permanent solution

Other solutions

•Controlled discharge – Bio-P removal, persistent algae

•Baffling systems – increase HRT, contact time

•Insulated covers (warmth) – increased cold-weather performance

•Aeration alone – metals precipitation, increased DO and mixing, algae reduction

Thank youQuestions?

Please contact us for more information about any of our solutions.

Kevin Bossy:[email protected]

Christine Gan:[email protected]

54

Lagoon Systems – Key microorganisms

Heterotrophic bacteria/archaea• Reduce organic carbon

o Requires DO, pH 7-8

• Reduce nitrates (via denitrification)o Requires low DO, also consumes organic carbon

o pH 7-8

Autotrophic bacteria/archaea • Reduces ammonia (NH3)

o Requires DO, pH 7 – 8.5

o Produces acid→ processconsumes alkalinity

Key elements for Dewatering Projects

Laydown Area – Design and Construction

• Level area• Solid base (sand)• Impermeable

geomembrane liner

• Add drainage media (crushed stone) to promote dewatering

• Deploy Geotube® unit onto cell

• Construct berms if needed

• Filtrate drainage (back to cell, holding tank)

*Project located in Weedon, QC

56

Bench testing and evaluation

Key elements for a Successful Dewatering Project

57

• Jar tests, RDT/GDT to determine chemicalconditioning program and dosage rates

• Estimate achievable % solids and filtrate quality


Bench testing and evaluation

58

• Software analysis• Estimate dewatered volumes, bag

dimensions, laydown area requirement, attained solids, stresses


Dredging and Pumping of Sludge

• Every project is different and maycall for different technologies to beused for the transfer of sludge

• Equipment is chosen based on:• Type of material• Pumping distance• Size of application• Vegetation• Scope of work

59


Dredging Options

Utilizing tractor PTOs in a small lagoon Dredging in Alexandria ON

60


Polymer Conditioning and Solids Flocculation

61

Chemicals are selected and optimized based on the sludge characteristics

Charge neutralization – “like getting magnets to come together”

Organic, InorganicNew Product: NEO - RE300

Coagulation (if needed)1

Particulates causing turbidity/TSS

Coagulant

Coagulated particles

1



62

Chemicals are selected and optimized based on the sludge characteristics

Flocculation – “like sweeping the magnets together into a pile”Organic polymers – cationic, neutral or anionic charges

Flocculation2

Particulates causing turbidity/TSS

Coagulated particles

FlocculationSedimentation

21



• Polymer Injection and Mixing using VEPAS (Venturi Emulsified Liquid Polymer Activation System) system

○ Mixing is achieved via the piping system and static mixers (if required)

○ Polymer injection controlled and is proportional to sludge flowrate (% solids)

VEPAS system at Farm process facility

63

Onsite Capabilities

➢ Fully automated chemical conditioning system

○ Specially designed to condition sludge for optimal dewatering

➢ We provide on-site pumping, chemical conditioning and Geotube® management services to municipal, industrial and private clients

64

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Onsite Capabilities - Turnkey Solutions

We offer turnkey process and permanent project management solutions, including:

• Mobilization and demobilization of equipment• Geotube® units• Chemical conditioning of sludge• Manpower, Onsite training

• Dewatering quality control • Consultation • Dredging

Onsite Capabilities - Turnkey Solutions

We also hold a mobile ECA issued by the MOE to perform Geotube®

dewatering projects

66

• The system is contained within a trailer or Sea-container which can be quickly mobilized

• A self-contained generator makes the system completely self sufficient in even the most remote of locations

67

Onsite Capabilities

Onsite Capabilities - VEPAS system

• % solids readings every 15 seconds• Polymer dosage rates

automatically adjusted accordingly

• Optimum flocculation of solids over the entirety of the project

• Can vary pump rates depending on requirements

VEPAS at Whiteside Farms

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Onsite Capabilities

• Data is collected over course of the project and provided to the client upon project completion

○ Daily Production

○ Volume of Material Processed

○ Average % Solids of Material Processed

69

Lagoon Systems - Overview

Many different interactions between bacteria, chemical contaminants, and environmental conditions (e,g, pH, sunlight/UV, temperature, wind, vegetation, etc.)

Like most ecosystems, lagoons are dynamic and complex

Key microorganisms:Heterotrophs → BOD-reducingAutotrophs (nitrifiers) → ammonia-reducing

Both are aerobic bacteria that thrive in oxygen-rich environments (lots of dissolved oxygen/DO)

Why is my lagoon underperforming?

Challenge: Overall reduced performance over time

Likely cause: Sludge accumulation

Sludge accumulation leads to:

• Low DO

•Reduced capacity/treatment

•Release of contaminants into water column Floating sludge on the surface of a lagoon system.

https://www.medoraco.com/

Sludge accumulation –how do you know it’s the issue?

Signs indicating you need to remove sludge:

• Floating sludge

• Putrid odours

• Increase in turbidity or changes in colour

• Blue green or green algae bloom

• Increases in effluent TSS or solid sludge particles in effluent

• Evidence of benthal feedback

Benthal feedback

• Sludge breakdown in bottom layers (benthic zone) of lagoon by anaerobic microorganisms

• Release of nutrients and accumulated sludge components back into water column

• Leads to release of BOD, TSS, NH3, P, low pH

Typically occurs when:

• Sludge blanket exceeds 18 inches/~20cm

• Dissolved oxygen <2mg/L

• Warm water temperatures (>15C) →increased anaerobic bacterial activity

Sludge can also accumulate faster based on:

•flows and organic loading

•lagoon size and depth

•debris/screening methods

•temperature, aeration/oxygen, etc.

Not just about lagoon age!

Why is my lagoon underperforming?

Challenge: Overall reduced performance over time;

Sludge accumulation and benthal feedback has been eliminated as the cause of reduced performance

Likely causes:

1. Short circuiting/washout

2. Reduced bacterial activity

3. Wastewater/environmental conditionsRelated

1) Short circuiting/washout

•Fluid dynamics are hard to predict

•Contact time between wastewater and microorganisms is crucial • Low HRT = washout, treatment

•Short circuiting can be a cause of poor design, peak flows (I&I, population growth), sludge accumulation, thermal stratification

https://www.environeticsinc.com

http://www.triplepointwater.com/

2) Reduced bacterial activity

Bacteria that “eat” organic carbon (BOD) are faster-growing than bacteria that “eat” ammonia, and will outgrow and outcompete them given the following:

•BOD/COD is much higher than ammonia (higher food availability for heterotrophs)

•Dissolved oxygen is limited (both microorganisms compete for O2)

Algae/microalgae growth leads to reduced bacterial activity

•Results from high BOD and nutrient loads, low DO, stagnant waters

•Can result in high effluent TSS and BOD (1 mg algal TSS ~ 0.5 mg BOD)

•Dead algae release nutrients (N and P) , accumulate as sludge, and further depletes oxygen levels

•Increases pH due to CO2 consumption, resulting in high pH and inability for nitrifiers to perform

•High pH also pushes ammonia equilibrium to increase unionized ammonia (increased failure of LC50 toxicity test)

2) Reduced bacterial activity

3) Environmental conditions

Cold water temperatures reduce efficiency and growth rate of bacteria

Warm temperatures and increased sunlight can increase algal growth and anaerobic activity

3) Environmental conditions

Other requirements for optimal biological activity (conditionally):

•pH between 7 - 8.5

•Sufficient alkalinity (CaCO3) (for nitrification)

•Oxygen transfer

•Sufficient HRT and mixing

•No toxicity

Lagoon performance flowchart (simplified)

POOR LAGOON PERFORMANCE/

EFFLUENT QUALITY

SLUDGE BUILDUP

Low DO

pH change

Algae growth

Temperature change

REDUCED BACTERIAL ACTIVITY

Increased flows

High BOD/NH3 loading

Decreased HRT

Benthal feedback

enhanced biological treatment and sludge management for ... conference... · circuiting/high flows,...

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