Metal Finishing Pretreatment in

Connecticut

SNEATP Tech Talk Presentation

Mariana MillerFebruary 10, 2015

What is Metal Finishing?

• ‘Finish’ a metal off by:– Depositing coatings of one metal on to another– Coating metals, based on specific requests from

customers– Producing specific designs or appearances on part

surfaces• Metal finishers – 47% of regulated CT industry

Pollutants generated

• Metals• Hexavalent chromium• Cyanides• Oils• Toxic organic compounds• Solids

Pretreatment

• Treatment plants are not designed to handle pollutants in raw wastewater

• Wastewater must be treated prior to discharge to sewer

• Prevents: – Interference with processes at the treatment plant– Pass through of pollutants

Common types of Pretreatment

• Metals precipitation prior to discharge– Neutralization– Flocculation/coagulation– Sludge dewatering

• Hexavalent chromium reduction• Cyanide destruction• Filtration• Oil/water separation• Haul wastewater

Without Pretreatment…

• EPA NPDES Permit Writers’ Course Workbook– Bottom left: Hexane explosion– Top right: Manhole cover blown off after gas

explosion– Bottom right: Buildup of hydrogen sulfide/buildup

of solidified oil• Other effects…

How is this regulated?

• Local, state, federal regulations• CT DEEP permits• Effluent limitations• Treatment plant’s review/approval• Inspections• Monthly reporting• Enforcement actions

Questions?