Title: General Operation and Maintenance of Systems using Aerobic Treatment, Disinfection and Spray field
1General Operation and Maintenance of Systems
using Aerobic Treatment, Disinfection and Spray
field
- Texas AgriLife Extension Service
2Overview
- Components in a system using Mechanical Aerobic
Treatment - Operational Evaluation
- Alarms
- General Considerations
- Parts Replacement
3Maintenance
- Routine performance checks, examinations, upkeep,
cleaning or mechanical adjustments to an onsite
sewage facility - Correct inoperable components or prevent
components from becoming inoperable
4Maintenance Training
- Required training is extensive
- OM checklists available _at_ http//ossf.tamu.edu
5Maintenance 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
6Scheduled/Preventative Maintenance
- Manufacturers guidance
- Aeration chamber inspection and evaluation
- Conditions around the aerobic treatment unit.
- Cleaning Media
- Filter Replacement
- Alarm Tests
- Wasting Solids
7Manufacturers 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.
8Aerobic Treatment Unit System
9ATU, 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
10Operational 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
11General 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
12Infiltration to System
- Water tightness critical for treatment
- Water entering
- Water exiting
- Hydraulic overloading flushes system
- Partially treated wastewater exits
- Solids carryover
- Dilutes microbial population
13Odor at Treatment Units
- Evaluate the presence of odors within 10 feet of
perimeter of system - None
- Mild
- Strong
- Chemical
- Sour
- Source of odor?
14Trash 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!!!
15Current tank operating condition
- a. Liquid level in respect to outlet (inches)
- At
- Above
- Below
- In_______
Above
At
Below
16SCUM LAYER
CLEAR LAYER
SLUDGE LAYER
17Septic/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?
18 Venting/Air supply
- Air supply method
- Aspirator
- Aerator
- Compressor
- Blower
- Free Air
19Aspirator/Aerator
- Vacuum pulls air into the water
- Spinning shaft or impeller causes the vacuum
- Check air flow
- Remove aerator
- Clean shaft
20Compressors
- 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
21Blowers
- Greater air flow
- Lower pressure
- Check inlet screens/filters
- Air flow discharge from unit
22Air Supply
- Operation
- Continuous
- Timed
- Aerator unit operating properly?
23Air 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
24Venting/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
25Air Supply
- Air flow at air supply unit
- Measured at the supply unit
- Positive pressure
- Compressor
- Blower
- Vacuum
- Aspirator
26Air Filters
- Air filter/screen
- Cleaned
- Washed/Dried
- Replaced
- Every Time
- Yearly
- Filter Locations
- Internal
- External
27Venting
- Venting appears
- operable
- Air entering system
- Air must exit somewhere
- Unit
- House vent
- Biofilter
28Conditions at the ATU (cont.)
- c. Was Foam/Residue observed outside of the unit?
29Aeration 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
30Aeration 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.
31Aeration chamber (cont.)
- f. Biomass color in aeration chamber
- Clear
- Brown
- Black
- g. Sludge pumping recommended
32Additional tasks for attached growth- media
evaluation
- a. Plugging
- b. Floating
- c. Media washed
- Air
- Water
- d. Media replaced
33Clarification 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
34Vertical Settling Chamber
- Flow is vertical through the chamber
- Upward flow rate must be less than the settling
rate
35Clarification chamber (cont.)
- a. Scum Layer
- b. Clear zone depth below outlet
- c. Effluent screen/tertiary filter cleaned
- d. DO in clarifier
36Clarification chamber (cont.)
- e. Effluent odor after exiting clarifier
- None
- Mild
- Strong
- f. Effluent color after exiting clarifier
- Clear
- Brown
- Black
37 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
38Sludge return operating (cont.)
- Note method for sludge return
- Passive
- Active
- a. If active, pump was checked manually
- b. Pump operating properly
39Disinfection 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.
40Tablet 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
41Residential 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
42Ultraviolet 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!!!!!!
-
43Pump 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
44Electrical 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!
45Dispersal System Maintenance
- Dependent on specific distribution method.
- More information about OM available at
- http//ossf.tamu.edu
46Spray 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.
47Spray Distribution Heads
- Need to stay in their design location
- Screens in heads
- Low pressure drain
- Rotor or Impact will wear out
- Damage - Lawn mower
48Pumping 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.
49Wasting 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
50Cautions 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
51Response to Alarms
- Alarms
- Audio
- Visual
- Alarms tell the owner
- Water level
- Air supply
- Response time
- 48 hours
- Read the contract
52Response 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.
53Parts 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.
54Emergency 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.
55Emergency 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.
56Summary
- Aerobic Treatment Unit System Components
- Airflow
- Feeding the System
- Alarms
- Operational Evaluation
- General Considerations
- Parts Replacement