Average power costs for industry for various countries are shown in the graph below. However, it must be emphasized that power cost varies quite significantly depending on following factors even in a same country Location – Depending on geographical location, power cost varies significantly. In the US, power costs tend to be low in Midwest […]

# Power calculation

# Motor efficiency

Electric motors are responsible for 90 percent of the electric energy consumption in a typical wastewater treatment plant.(WEF 2009, — USEPA 2010). Motor efficiency () is a measure of mechanical power () output compared to electrical power input (). ————————————— (1) where = mechanical power output (W or hp) = electrical power input […]

# Pump power calculation

The efficiency of pump (εp) is defined as the ratio of power transferred to water to the power supplied to the pump. The latter is equal to the brake horsepower of motor (PM). If gear box is used to reduce motor speed, the gear box efficiency (~95%) must be multiplied to PM to obtain the real […]

# Blower power calculation – Blower types and efficiency

Table 1. Overview of blower types for aeration of wastewater (– USEPA, 2010) Table 2. Typical efficiencies (– USEPA, 2010) Blower Type Nominal Blower Efficiency (%) Nominal Turndown (% of rated flow) Positive displacement (variable speed) 40-65 50 Multi-stage centrifugal (inlet throttled) 50-70 60 Multi-stage centrifugal (variable speed) 60-70 50 Single-stage centrifugal, integrally geared (with […]

# Blower power calculation

Blowers can be categorized as either (1) positive displacement blowers, which provide a constant volume of air at a wide range of discharge pressures, or (2) centrifugal blowers, which provide a wide range of flow rates over a narrow range of discharge pressure (– USEPA 2010). Table 1 summarizes the types of blowers in each category […]