Bharat Heavy Electricals Limited (BHEL)
The Challenge
Restoring a Critical Metal-Finishing ETP to PSU-Grade Compliance
BHEL's Heavy Electrical Equipment Plant in Haridwar operates a vibro-finishing line for turbine blades, whose effluent carries metal fines, abrasive particles and deburring and polishing chemicals. Spans Envirotech was engaged to recondition and retrofit the 1 KLD physico-chemical effluent treatment plant serving this line.
As a PSU project, the compliance bar was high: the treated effluent had to meet UKPCB and Environment Protection Rules Schedule-VI limits — including total metals ≤10 mg/L, COD ≤250 mg/L, oil and grease ≤10 mg/L and pH 6.5–9.0 — and the plant had to run reliably and unattended, independent of the machines it serves.
Key Issues:
- !Metal-bearing effluent from turbine-blade vibro-finishing (metal fines, abrasives, polishing chemicals)
- !Stringent PSU discharge norms — total metals ≤10 mg/L, COD ≤250 mg/L, O&G ≤10 mg/L
- !Ageing plant requiring full mechanical and electrical reconditioning in situ
- !Stand-alone, automated operation independent of the finishing machines
The Solution
Full In-Situ Reconditioning with Stand-Alone PLC Automation
Spans carried out a complete reconditioning and retrofit on site — replacing five tanks, the piping and valves, dosing and pH-control systems, agitator and air compressor, plus roughly six pumps and ten motors. A physico-chemical treatment train sequences a sedimentation tank, pH-controlled neutralization, an aeration/air-bubble stage, settling, a bag filter, a multi-media filter and an activated carbon filter to meet the metals and COD limits.
The plant was re-automated with a new electrical panel and a Siemens S7-200 Smart PLC and HMI running stand-alone operation logic, so the ETP operates independently of the vibro-finishing machines' status. Spans' scope also covered switchgear and rewiring, a year of consumables, commissioning, a 15-day supervised trial run, and operator and maintenance training — all executed in situ at the BHEL premises.
Technologies Deployed:
Implementation Timeline:
Plant Assessment & Scope Definition
Assessed the existing 1 KLD ETP against UKPCB Schedule-VI acceptance criteria and defined the mechanical, electrical and automation reconditioning scope.
Mechanical Reconditioning
Replaced five tanks, piping and valves, dosing and pH systems, agitator, air compressor, and roughly six pumps and ten motors.
Electrical & PLC Automation
Installed a new panel, switchgear and rewiring with a Siemens S7-200 Smart PLC/HMI running stand-alone operation logic.
Commissioning, Trial Run & Training
Commissioned the plant with a 15-day supervised trial run, one year of consumables, and operator and maintenance training.
The Results
Engineering & Design Highlights
1 KLD
Design Capacity
Physico-chemical ETP for turbine-blade metal-finishing effluent
≤10 mg/L
Total Metals Target
Engineered to UKPCB / EP Rules Schedule-VI limits, with COD ≤250 mg/L and O&G ≤10 mg/L
Stand-Alone PLC
Automation
Siemens PLC/HMI logic runs the ETP independently of the finishing machines
Full Retrofit
Scope
In-situ reconditioning, automation, commissioning, trial run and operator training
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