| Saving Water and Reducing Wastewater Discharges at a Metal Finishing Plant | Latvia | 1993 | Full scale |
MANUFACTURE OF OTHER TRANSPORT EQUIPMENT # 4
Background
Founded in 1866, the State Joint Stock Company "Lokomotive" is a large plant in Latvia that builds and refurbishes diesel locomotives from Central and Eastern European customer. The plant is vertically integrated and includes operations for manufacturing and remanufacturing electric motors, steel casting, forging, machine shops, electrical shops, and metal finishing. Lokomotive employs over 2,700 persons including 2,200 production workers.
The metal finishing facility was subjected to pollution prevention diagnostic audit under WEC's waste minimization program.
Cleaner Production Principle
Recovery, Reuse and Recycle; Process modification
Cleaner Production Application
Water conservation during locomotive cleaning operations
As part of the refurbishing operations at Lokomotive, the locomotives are cleaned with steam and hot water in a specially designed booth. Wastewater generated from the cleaning operations is contaminated with oil, grease, paint, and solid materials. The wastewater is sent to the plant's wastewater treatment facility before discharge to the city sewer. In the past, the steam and hot water used in the cleaning operations were generated from the plant's fresh water supply. Costs associated with this practice include the cost of fresh water, wastewater treatment costs and environmental fees based on the amount of contaminated wastewater discharged from the plant.
During the waste minimization project, it was determined that treated effluent water from the company's metal finishing operations could be used in place of fresh water for locomotive cleaning. Previously, the metal finishing effluent water was treated and discharged to the city sewer. To implement the project, the company installed water storage tanks, piping, and other related equipment. The majority of the necessary equipment was available on-site.
Water conservation at metal finishing shop
Lokomotive operates an metal finishing shop as part of its locomotive building and refurbishing operation. In the past, the facility consumed excessive amounts of water and discharged large amounts of wastewater because it lacked up-to-date processes, equipment and procedures for rinsing of parts.
During the waste minimization project, a comprehensive evaluation of the rinsing operations at Lokomotive was conducted to identify opportunities for reducing water consumption and wastewater discharges. Following improvements were identified and implemented which are basically simple low cost equipment modifications, changes in operating practices, and process control.
| Countercurrent rinsing methods were adopted to improve water use efficiency. |
| Conductivity controllers were installed on rinse water baths to supply water only when conductivity exceeds preset parameters. |
| Rinse water feed spargers (perforated pipes) were installed for better mixing of fresh water to the rinse water bath. |
| Dwell time over metal finishing tanks was increased to reduce carry over of plating solution into the rinse baths. |
| Flow meters with hand controls and hand-operated valves were installed on water lines to measure and control the flow rate of water to the rinse tanks. |
Environmental and Economic Benefits
Water conservation during locomotive cleaning operations
As a result of the project, the company reduced its fresh water consumption by 20,000 m3/year and reduced its wastewater discharges by the same amount.
The modification cost $4,500, resulted in a saving of 10,600 a year, and had a payback period of less than six months.
Water conservation at metal finishing shop
As a result of the waste minimization project, the company reduced fresh water usage by 8,700 m3/year and decreased wastewater discharges by the same amount. The project also reduced the amount of heavy metals discharged to water and land and decreased the amount of environmental fees paid by the plant.
The equipment cost $9,862 and was paid for by the United States Agency for International Development. It resulted in yearly savings of $11,000 per year and a payback period of less than eleven months.
Constraints
None reported.
Contacts
Review Status
This case study was taken from the WEC publication "Economic and Environmental Benefits of Industrial Waste Minimization in Estonia, Latvia and Lithuania" (1995). It was edited for the UNEP IE ICPIC diskette in June 1997.
Subsequently the case study has undergone a technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.