General Operation and Maintenance of Systems using Aerobic Treatment, Disinfection and Spray field

1
General Operation and Maintenance of Systems
using Aerobic Treatment, Disinfection and Spray
field

• Texas AgriLife Extension Service

2
Overview

• Components in a system using Mechanical Aerobic
  Treatment
• Operational Evaluation
• Alarms
• General Considerations
• Parts Replacement

3
Maintenance

• Routine performance checks, examinations, upkeep,
  cleaning or mechanical adjustments to an onsite
  sewage facility
• Correct inoperable components or prevent
  components from becoming inoperable

4
Maintenance Training

• Required training is extensive
• OM checklists available _at_ http//ossf.tamu.edu

5
Maintenance frequency

• Why have a maintenance frequency?
• Regulatory guidance
• Treatment processes mechanical parts
• Who sets the timing of activities?
• TCEQ minimum guidance
• Local authorized agent
• NSF Standard 40 guidance
• Manufacturer of products
• Designer

6
Scheduled/Preventative Maintenance

• Manufacturers guidance
• Aeration chamber inspection and evaluation
• Conditions around the aerobic treatment unit.
• Cleaning Media
• Filter Replacement
• Alarm Tests
• Wasting Solids

7
Manufacturers required maintenance performed

• Generally manufacturers have specified
  maintenance for their proprietary products.
• Check with the manufacturer of the specific
  product for additional activities.
• Perform the additional specified operation and
  maintenance procedures.
• Document performance of the activities.
• Manufacturers required to make parts available.

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Aerobic Treatment Unit System
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ATU, Disinfection and Spray Distribution System
Components

• Septic/Trash tank
• Aerobic Treatment
• Air Supply
• Clarification
• Sludge Return
• Disinfection
• Pump tank with pump and controls
• Spray field

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Operational Evaluation

• General site
• Trash tank
• Aerators (Air Supply Operational)
• Filters
• Air
• Screen
• Pumps
• Irrigation
• Recirculation

• Sludge condition
• Disinfection Device
• Chlorine Supply
• Electrical Circuits
• Distribution System
• Spray field vegetation/seeding
• Manufacturer Required Maintenance

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General Site Conditions

• Power is on!!!
• Conditions at the tanks
• Accessibility to components
• Surface water drainage away from tanks
• Lids able to be removed and secured

12
Infiltration to System

• Water tightness critical for treatment
• Water entering
• Water exiting
• Hydraulic overloading flushes system
• Partially treated wastewater exits
• Solids carryover
• Dilutes microbial population

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Odor at Treatment Units

• Evaluate the presence of odors within 10 feet of
  perimeter of system
• None
• Mild
• Strong
• Chemical
• Sour
• Source of odor?

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Trash Removal and Anaerobic Treatment

• Generally referred to as the trash tank or
  septic tank
• Removes non degradable materials from the waste
  stream.
• Provides anaerobic treatment.
• Can be used as a component of a denitrification
  process
• Most trash tanks are not easily accessible!!!

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Current tank operating condition

• a. Liquid level in respect to outlet (inches)
• At
• Above
• Below
• In_______

Above
At
Below
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SCUM LAYER
CLEAR LAYER
SLUDGE LAYER
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Septic/Trash tank pumping recommended?

• Should be pumped when total solids reach 25-33
  of tank capacity.
• If A is less than 3
• If B is less than 12

If recommended, did it happen?
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Venting/Air supply

• Air supply method
• Aspirator
• Aerator
• Compressor
• Blower
• Free Air

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Aspirator/Aerator

• Vacuum pulls air into the water
• Spinning shaft or impeller causes the vacuum
• Check air flow
• Remove aerator
• Clean shaft

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Compressors

• Greater pressure
• Lower air flow
• Two distinct types of compressors
• Rotary
• Linear
• Listen for operation
• Check operating pressure
• Clean Filters
• Rebuild as necessary

Rotary
Linear
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Blowers

• Greater air flow
• Lower pressure
• Check inlet screens/filters
• Air flow discharge from unit

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Air Supply

• Operation
• Continuous
• Timed
• Aerator unit operating properly?

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Air Dispersion

• Introduces air into the water
• Supply lines
• Dispersion methods
• Holes
• Slots
• Porous material
• Potential for plugging in the orifices that could
  reduce air flow

Perforated Pipe
Porous Stone Diffuser
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Venting/Air supply
Pressure Gage

• Pressure at air supply unit
• Where
• Measured at the unit
• Pressure gage
• Schrader valve
• What should it be?
• Flow pressure curve
• How to read it

Schrader Valve
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Air Supply

• Air flow at air supply unit
• Measured at the supply unit
• Positive pressure
• Compressor
• Blower
• Vacuum
• Aspirator

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Air Filters

• Air filter/screen
• Cleaned
• Washed/Dried
• Replaced
• Every Time
• Yearly
• Filter Locations
• Internal
• External

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Venting

• Venting appears
• operable
• Air entering system
• Air must exit somewhere
• Unit
• House vent
• Biofilter

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Conditions at the ATU (cont.)

• c. Was Foam/Residue observed outside of the unit?

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Aeration chamber

• a. Mixing in aeration chamber
• Rolling motion
• b. DO in aeration chamber
• 2 mg/L
• c. pH in aeration chamber
• 7.0
• d. Temperature in aeration chamber
• Room temperature
• Collect sample from aeration chamber
• Difficult in many systems!!!
• Measure items

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Aeration chamber (cont.)

• e. Settlability test - MLSS
• 30 Minute Settleability Test
• Beaker with 10 even gradations
• Fill beaker with sample from aeration chamber.
• Let stand for 30 minutes and read level of clear
  zone.
• 20 to 60 is ok.

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Aeration chamber (cont.)

• f. Biomass color in aeration chamber
• Clear
• Brown
• Black
• g. Sludge pumping recommended

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Additional tasks for attached growth- media
evaluation

• a. Plugging
• b. Floating
• c. Media washed
• Air
• Water
• d. Media replaced

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Clarification chamber

• Process occurs in a clarifier
• Clarification is the process were the microbes,
  cell waste and biomass settle out of the water.
• Sludge blanket in the bottom and a clear zone
  below the discharge point

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Vertical Settling Chamber

• Flow is vertical through the chamber
• Upward flow rate must be less than the settling
  rate

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Clarification chamber (cont.)

• a. Scum Layer
• b. Clear zone depth below outlet
• c. Effluent screen/tertiary filter cleaned
• d. DO in clarifier

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Clarification chamber (cont.)

• e. Effluent odor after exiting clarifier
• None
• Mild
• Strong
• f. Effluent color after exiting clarifier
• Clear
• Brown
• Black

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Sludge return operating

• Settled solids passing into a previous treatment
  chamber
• Passive system
• Settled solids passing through the bottom opening
• Active system
• Settled solids blanket below the outlet baffle

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Sludge return operating (cont.)

• Note method for sludge return
• Passive
• Active
• a. If active, pump was checked manually
• b. Pump operating properly

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Disinfection Device

• Removes pathogens (disease-causing organisms)
  from the wastewater.
• Chlorination is the most common Disinfection
  method.
• Ultraviolet light is an additional method.
• Chlorine supply must be present.

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Tablet Chlorination

• Tablet chlorinators generally have four
  components
• Chlorine Tablets.
• A tube that holds the tablets.
• A contact device, which puts the chlorine tablets
  into contact with the wastewater.
• A storage reservoir, usually a pump tank where
  the water is stored before it is distributed.
• Chlorine residual 0.1 mg/L

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Residential Liquid Chlorination

• Flow passes through aspirator developing a vacuum
  or through a pump to draw a dose of chlorine.
• Tubing delivers chlorine dose to aspirator or
  pump
• Control volume of chlorine
• Mixing of chlorine with effluent
• Chlorine residual 0.1 mg/L

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Ultraviolet Light Disinfection

• Effluent flows past the light bulb exposing
  pathogens to UV light
• a. Is power supplied to the unit?
• b. Is the UV lamp on? Time of lamp operation is
  critical
• c. Is the electrical system free of corrosion or
  damage?
• d. Was the ballast replaced during this visit
• Fecal Coliform Test less than 200 colony
  forming units per 100mL
• DO NOT LOOK AT LIGHT!!!!!!

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Pump Tank Maintenance

• Check for solids accumulation in the bottom of
  the tank. Pump tank if necessary.
• Check the water level sensors
• Check action of the floats.
• If float tree can remove to check floats
• Remove the pump and check the inlet screen for
  accumulation of material

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Electrical Circuits

• Panel is a housing for components needed to
  control a system.
• Record valuable operational information
• Provide a means to collect operational data on
  the system
• Power must be ON!

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Dispersal System Maintenance

• Dependent on specific distribution method.
• More information about OM available at
• http//ossf.tamu.edu

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Spray Field Vegetation

• Vegetation growing for water and nutrient
  removal.
• Clear area around spray head 10 feet in the
  direction of spray from the head.
• Dead vegetation should be reseeded to establish
  vegetation.

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Spray Distribution Heads

• Need to stay in their design location
• Screens in heads
• Low pressure drain
• Rotor or Impact will wear out
• Damage - Lawn mower

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Pumping Tanks to Manage Microbial Biomass Sludge

• Sludge wasting is required to reduce the quantity
  of biomass in the system.
• Frequency depends on the waste load into the
  system. High organic loading requires larger
  microbial population to transform waste
• 30 minute settleability test is used to determine
  when system needs pumping.

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Wasting Sludge from System

• Turn the aeration system off.
• Extend the pump hose to the bottom of the
  aeration chamber.
• Pump out aeration chamber, trash tank and bottom
  of pump tank.
• Do not flush materials back into the aeration
  unit from the pump truck.
• If concern about unit restarting, collect about
  five gallons of mixed liquor and put into tank
  with clean water.
• Refill the unit with clean water.
• Turn aerator back on

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Cautions when pumping tanks

• Check for media in tank
• Dirty media needs water to support weight
• Be aware of tank floatation/crushing
• Wet soil conditions around tank can float tank
• Wet soil conditions may lead to a crushed tank
• Aeration system needs back pressure
• Aeration system should be off until tank refilled
• Complete pumping is best
• No starter microbes needed for operation

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Response to Alarms

• Alarms
• Audio
• Visual
• Alarms tell the owner
• Water level
• Air supply
• Response time
• 48 hours
• Read the contract

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Response to Alarms

• When Alarm goes off
• Silence the buzzer alarm.
• Reduce your water use to a minimum.
• Investigate the reason for the alarm
• Take appropriate action for correcting the alarm
  condition.

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Parts Replacement

• Manufacturer specific parts.
• NSF International Standard 40 testing protocol
  evaluated configuration of components
• Must maintain manufacturers components to meet
  certification
• Be sure to utilize only approved replacement
  parts.

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Emergency Repairs

• An emergency repair may be made to an OSSF
  providing that the repair
• Is made for the abatement of an immediate,
  serious and dangerous health hazard and
• Does not constitute an alteration of that OSSF
  systems planning and materials function.

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Emergency Repairs Cont.

• Types of Emergency repairs
• replacing tank lids,
• replacing inlet and outlet devices, and
• repairing solid lines.
• Repairs must be in compliance with chapter 285
• Installer must notify permitting authority
• in writing,
• within 72 hours of starting the emergency
  repairs.
• include a detailed description of the methods and
  materials used in the repair.
• Permitting Authority may inspect emergency
  repairs.

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Summary

• Aerobic Treatment Unit System Components
• Airflow
• Feeding the System
• Alarms
• Operational Evaluation
• General Considerations
• Parts Replacement