The calculation of electrical energy consumption (as a plant-specific optimal value) for the RRC in Qingdao ShiYuan is based on the machinery list, using empirical values from the German draft standard DWA-A 216 (DWA 2013). Smaller consumers, such as the instrumentation, control and automation systems or lighting, have been neglected. For the rough calculation of the electricity consumption for the reference design and a conventional system, the same boundary conditions (e.g., discharge head for pumps or specific electricity consumption for machines) are used. Data related to the electricity demand for waste and sludge treatment, as well as exhaust air purification, are not discussed in this paper, although they contribute considerably to the energy requirements of an RRC (Tolksdorf et al. 2015). Table 1 gives an overview of the scenarios. For all scenarios, 12,000 population equivalent was assumed.

Table 1

Characteristics of scenarios

SEMIZENTRAL reference designSEMIZENTRAL Qingdao ShiYuanConventional system AConventional system B
Wastewater L/(C·d) Greywater: 41 Blackwater: 68 Greywater: 60 Blackwater: 68 Total: 128 Total: 282
Water reuse Treated greywater for toilet flushing Treated greywater for toilet flushing Treated blackwater for irrigation None None
Co-substrate gDS/(C·d) Biowaste: 270 Food waste: 171 None None
SEMIZENTRAL reference designSEMIZENTRAL Qingdao ShiYuanConventional system AConventional system B
Wastewater L/(C·d) Greywater: 41 Blackwater: 68 Greywater: 60 Blackwater: 68 Total: 128 Total: 282
Water reuse Treated greywater for toilet flushing Treated greywater for toilet flushing Treated blackwater for irrigation None None
Co-substrate gDS/(C·d) Biowaste: 270 Food waste: 171 None None

DS – dry solids.

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