Wastewater treatment plant and related method with biological treatment process and heat transfer means

A wastewater treatment plant comprising:

• an input configured for receiving wastewater for treatment;
• an output configured for discharging wastewater after treatment;
• wherein a flow of wastewater is defined by the input and the output;
• a treatment stage between the input and the output and configured for reducing contaminants in the wastewater to form treated wastewater mostly free of contaminants;
• wherein the treatment stage includes:
• a biological-process substage configured for growing unicellular organisms adapted to reduce contaminants in the wastewater which are dissolved, including at least one of organic matter and nitrogenous matter, by digestion thereof, and which are adapted to floc after digestion;
• a floc-removal substage downstream from the biological-process substage, relative to the flow of wastewater, and configured for removing the unicellular organisms that have flocked;
• wherein the treatment stage is further configured to form, downstream of the floc-removal substage, majority and minority flows of the treated wastewater respectively comprising majority and minority volumes of a common substance which is the treated wastewater;
• wherein the minority flow of the treated wastewater is configured to be recycled upstream of the biological-process substage of the treatment stage;
• and
• a heat transfer assembly operatively coupled to each of the majority and minority flows of the treated wastewater and configured for transferring heat from the majority flow of the treated wastewater to the minority flow of the treated wastewater to increase temperature of the minority flow of the treated wastewater for subsequently increasing temperature of wastewater to be treated upon recycling of the heated minority flow upstream of the biological-process substage;
• and wherein the heat transfer assembly comprises a first heat exchanger fluidically coupled to the majority flow of the treated wastewater, a second heat exchanger fluidically coupled to the minority flow of the treated wastewater and an intervening heat pump fluidically coupled between the first and second heat exchangers, so that heat is transferred from the majority flow of the treated wastewater to heat transfer fluid, and therefrom to the minority flow of the treated wastewater.