The Sludge-to-Sludge Heat Exchanger from Walker Process Equipment, A Div. of McNish Corp., has a concentric tube-in-tube design that uses counterflow circulation of heated thermophilic biosolids and raw influent. This arrangement provides a means to cool thermophilic biosolids and reduces the amount of energy required to heat raw biosolids. It provides heat transfer with low headloss. End castings are removable for cleaning and include built-in water backflushing connections. It complies with ASME pressure vessel code requirements and is stamped with the ASME “U” symbol. Controls include nonflow restrictive temperature sensors and glass tube or dial thermometers to measure inlet and outlet sludge temperatures, as well as thermocouple and resistance temperature detector capable for remote indication of control. 630-892-7921; www.walker-process.com