Comparison of technology, costs and environmental benefit of wastewater treatment plants in mountainous areas in the alps

Brunnstein Refuge

Site description and boundary conditions
Design and treatment efficiency

Site description and boundary conditions

boundary conditions
maximum daily organic load [PE]	115
maximum hydraulic load [m3/d]	1.5
annual organic load [kg BOD/a]	360
altitude [m a.s.l.]	1560
sensitivity [hydrogeology, protected area ...]	nature reserve, limestone
lagal requirements [BOD elimination]	>80 %
operation period [season]	summer
energy supply [type, kW]	PV, 0.9; Aggregate, 11
means of transport [type]	supply cable car
existing WWTP [type, condition, volume l/PE]	2-chambers, poor condition, 13

 
 

Fig. 4.6: Flow-scheme of the WWTP Brunnstein Refuge

 

Fig. 4.7a: View of the 3-storied sanitary building (toilets and treatment units)

Fig. 4.7b: Soilfilter cage and splash compensator for the wastewater distribution

Design and treatment efficiency

Loading of the biological treatment
 

WWTP Brunnstein Refuge	seasonal average	max. week	max. day
loading [PE35] *)	28	38	115
BOB 5-load [kg/d]	1.0	1.3	4.0
influent flow Q [m3/d]	0.5	1.3	1.5

*)  PE 60 -specific organic load after dry toilets and grease trap: 35 g BOD 5 / PW60.d

 

Design of the composting process Mtotal, wet = 240 g/PW 60 x 6.000 PW60 x 2 = ca. 2.900 kg/a (total spareted solids) Factor 2 for added composting material (straw, sawdust,...) Mtotal, stabilized = ca. 960 kg/a (stabilized considering evaporation) 960 kg Compost in 3 compost toilets -> 2 times emptying / year Design of soilfilters according to the surface loading in max. week Vfixed bed = ca. 1.4 x 3 = 4.2 m3; OBF = ca. 4.2 m3 * 120 m2 / m3 = 500 m 2 (biofilm surface) BBF = 1300 g BOD5 / 500 m2 = 2.7 g BOD5 / m2.d (biofilm surface load)

 

Energy demand:
 

max. power [W]	max. electric work [kWh/d]	mean electric work [kWh/d]
130	0,56	0,38

 

Treatment efficiency:
 

date [dd.mm.yyyy]	CODeffluent [mg/l]	NH4-N effluent [mg/l]	NO3-N effluent [mg/l]	CODelimination [%]	Nelimination [%]	loading [% of PE max]
31.08.2000	150	2	15	87	78	48
22.07.2001	45	0.5	16	98	91	57

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