An improved clarifier tank having a rake arm assembly with one or more rake arms, a rake arm driveshaft operatively connected to the rake arms and a rake arm drive, and a sump scraper driveshaft, operatively connected to a plurality of sump scrapers and a sump scraper drive.

An improved clarifier tank having a rake arm assembly with one or more rake arms, a rake arm driveshaft operatively connected to the rake arms and a rake arm drive, and a sump scraper driveshaft, operatively connected to a plurality of sump scrapers and a sump scraper drive.

An improved clarifier tank having a rake arm assembly with one or more rake arms, a rake arm driveshaft operatively connected to the rake arms and a rake arm drive, and a sump scraper driveshaft, operatively connected to a plurality of sump scrapers and a sump scraper drive.

An improved clarifier tank having a rake arm assembly with one or more rake arms, a rake arm driveshaft operatively connected to the rake arms and a rake arm drive, and a sump scraper driveshaft, operatively connected to a plurality of sump scrapers and a sump scraper drive.

An improved clarifier tank having a rake arm assembly with one or more rake arms, a rake arm driveshaft operatively connected to the rake arms and a rake arm drive, and a sump scraper driveshaft, operatively connected to a plurality of sump scrapers and a sump scraper drive.

An improved clarifier tank having a rake arm assembly with one or more rake arms, a rake arm driveshaft operatively connected to the rake arms and a rake arm drive, and a sump scraper driveshaft, operatively connected to a plurality of sump scrapers and a sump scraper drive.

A settling basin of a wastewater treatment system includes a collector chain including chain links having a plurality of side bars, stepped connecting pins configured to join the plurality of side bars and including a first end including a head portion having a cross-sectional area larger than portions of the plurality of side bars through which the stepped connecting pin extends, end caps configured to receive second ends of the stepped connecting pins, and apertures defined in the end caps and second ends of the stepped connecting pins configured to receive a retaining element that holds the end caps in position on the second ends of the stepped connecting pins.

A settling basin of a wastewater treatment system includes a collector chain including chain links having a plurality of side bars, stepped connecting pins configured to join the plurality of side bars and including a first end including a head portion having a cross-sectional area larger than portions of the plurality of side bars through which the stepped connecting pin extends, end caps configured to receive second ends of the stepped connecting pins, and apertures defined in the end caps and second ends of the stepped connecting pins configured to receive a retaining element that holds the end caps in position on the second ends of the stepped connecting pins.

A head shaft assembly has a center tube, an end tube, a collector sprocket and a collar. The center tube has drive and driven ends. The center tube has a center tube diameter. The end tube has a key extending longitudinally along an outer surface and inner and outer ends. The key defines a key length and the end tube has an end tube diameter. The collector sprocket is mountable to the end tube and rotationally secured to the end tube by the key. The collar is hollow between a first end and a second end. The center tube diameter is substantially the same as the end tube diameter and the drive end is proximate to the inner end. The drive end and the inner end are positioned within the collar between the first end and the second end. The collar fixes the center tube to the end tube.

A head shaft assembly has a center tube, an end tube, a collector sprocket and a collar. The center tube has drive and driven ends. The center tube has a center tube diameter. The end tube has a key extending longitudinally along an outer surface and inner and outer ends. The key defines a key length and the end tube has an end tube diameter. The collector sprocket is mountable to the end tube and rotationally secured to the end tube by the key. The collar is hollow between a first end and a second end. The center tube diameter is substantially the same as the end tube diameter and the drive end is proximate to the inner end. The drive end and the inner end are positioned within the collar between the first end and the second end. The collar fixes the center tube to the end tube.