Septic Tank¶

QSDsan: Quantitative Sustainable Design for sanitation and resource recovery systems This module is developed by:

Yalin Li <mailto.yalin.li@gmail.com>

Hannah Lohman <hlohman94@gmail.com>

Tori Morgan <vlmorgan@illinois.edu>

This module is under the University of Illinois/NCSA Open Source License. Please refer to https://github.com/QSD-Group/QSDsan/blob/main/LICENSE.txt for license details.

class qsdsan.unit_operations.static._septic_tank.SepticTank(ID='', ins: Sequence[AbstractStream] | None = None, outs: Sequence[AbstractStream] | None = (), thermo=None, init_with='WasteStream', include_construction=True, degraded_components=('OtherSS',), if_capture_biogas=False, if_N2O_emission=True, if_include_front_end=True, if_generate_struvite=True, if_struvite_in_sludge=True, ppl=1, sludge_moisture_content=0.95, **kwargs)¶

Septic tank that anaerobically treat the influent waste stream, often used as a primary treatment unit.

Designed based on the Reclaimer system as described in http://washaid.pratt.duke.edu/sites/washaid.pratt.duke.edu/files/u71/Reclaimer_July2021.pdf and Trotochaud et al.

The following impact items should be pre-constructed for life cycle assessment: FRP, Pump.

Parameters:

ins (Iterable(stream)) – waste: liquid waste stream to be treated by septic tank unit. MgOH2: input Mg(OH)2 for struvite precipitation.
outs (Iterable(stream)) – treated: treated liquid leaving septic tank. CH4: fugitive CH4 emissions. N2O: fugitive N2O emissions. sludge: solid waste to be sent to sludge pasteurization, could include the precipitated struvite. struvite: a separate struvite stream when if_generate_struvite is True.
if_include_front_end (bool) – If the front end is included in the analysis.
if_generate_struvite (bool) – If generating struvite.
if_struvite_in_sludge (bool) – If the generated struvite is in sludge.
ppl (int) – Total number of users for scaling of costs.
sludge_moisture_content (float) – Moisture content of the sludge, assumed to be 0.95 based on Tchobanoglous et al. (sludge leaving anaerobic treatment 2-5% solids).

Examples

>>> from qsdsan.utils import create_example_sanitation_components
>>> cmps = create_example_sanitation_components()
>>> from qsdsan import System, WasteStream
>>> from qsdsan.unit_operations import SepticTank
>>> ws = WasteStream('ws', H2O=1000, NH3=5, NonNH3=2, P=2, K=1,
...                  OtherSS=30, units='kg/hr')
>>> mg = WasteStream('mg', MagnesiumHydroxide=1, units='kg/hr')
>>> ST = SepticTank('ST', ins=(ws, mg),
...                 outs=('treated', 'CH4', 'N2O', 'sludge', 'struvite'),
...                 decay_k_COD=3, decay_k_N=3, max_CH4_emission=0.25, ppl=4)
>>> sys = System('sys', path=(ST,))
>>> sys.simulate()
>>> round(ST.design_results['FRP'], 1)  # kg fiber-reinforced plastic
1147.5

See the EXPOsan reclaimer systems for use in a complete system.

References

[1] 2019.06 Technical report for BMGF V3 _ CC 2019.06.13.pdf [2] Tchobanoglous et al., Wastewater Engineering: Treatment and Resource Recovery, McGraw-Hill Education, New York, 5th edn., 2013.