Current through August 31, 2023
01.
Chemical Treatment. Many chemicals in various forms can be applied
in wastewater treatment to aid in nutrient removal, pH adjustment, enhanced
clarification, and sludge conditioning. Chemicals must be evaluated for each
specific treatment process and must be compatible with other liquids, solids
and air treatment processes. Laboratory tests such as jar tests or pilot-scale
studies on actual process wastewater shall be used to select appropriate
chemicals and dosage ranges. (3-31-22)
a.
Phosphorus removal. Chemical phosphorus removal from wastewater involves the
addition of metal salts (aluminum or iron) or lime to wastewater to form
insoluble phosphate precipitates, removal of the precipitate from the
wastewater, and disposal of the precipitate with the settled sludge. Many
process options are available, and the designer shall select the chemical to
insolubilize the phosphorus, estimate the dosage requirements, and select the
point of chemical addition. (3-31-22)
b. Nitrogen Removal. Several chemical
processes have been used for nitrogen removal. The three (3) major processes
include breakpoint chlorination, selective ion exchange, and air stripping.
Although these processes are technically feasible ways of removing nitrogen,
the Department does not anticipate widespread use of chemicals for nitrogen
removal, and justification to do so shall be demonstrated in the Preliminary
Engineering Report. (3-31-22)
c. pH
Adjustment. A common chemical process used in wastewater treatment is pH
adjustment. Several methods are available to neutralize or adjust low pH
wastewater. The methods used shall be mixing acid wastes with lime slurries, or
adding the proper amount of concentrated caustic soda (NaOH) or soda ash
(Na2CO3) as determined in the
Preliminary Engineering Report. (3-31-22)
d. Enhanced Primary Clarification. When
settling aids are used during the primary clarification process to enhance
solids removal in the primary treatment process, the additional solids volume
shall be accounted for in pumping, solids handling, stabilization, and disposal
processes. The coagulant shall be added and mixed before the sedimentation
process. Flocculants, if used, shall be added after the coagulant. The design
shall provide for chemical addition points at several locations to give process
personnel the opportunity to adjust for optimum performance.
(3-31-22)
02.
Filtration for Tertiary Treatment. Details for plants with
tertiary treatment utilizing filtration shall be submitted and approved in the
Preliminary Engineering Report. (3-31-22)
a.
Membranes. In addition to requirements of Section
411, details shall include plant
layout, calculations for hydraulic capacity and air required, membrane
technology considered and membrane type and model selected, results from
similar type filtration plants already in operation, and anticipated sludge
production. (3-31-22)
b. Media. In
addition to requirements of Section
411, details shall include plant
layout, calculations for hydraulic capacity, media considered and media type
selected, results from similar type filtration plants already in operation, and
anticipated sludge production. (3-31-22)
c. Cloth. In addition to requirements of
Section 411, details
shall include plant layout, calculations for hydraulic capacity, technology
considered and type and model selected, results from similar type filtration
plants already in operation, and anticipated sludge production.
(3-31-22)
d. Reverse Osmosis. In
addition to requirements of Section
411, details shall include plant
layout, calculations for hydraulic capacity required, technology considered and
type and model selected, results from similar type filtration plants already in
operation, and anticipated sludge production. (3-31-22)