Performance Metrics Used to Evaluate a Water Sewage Plant

Performance Metrics Used to Evaluate a Water Sewage Plant

The following performance indicators can be used in the performance evaluation of a water sewage plant. Accurate performance evaluation of a water sewage plant is an essential consideration when taking account of regulatory compliance, protection of public health, and operational performance improvement. It is proposed a set of indicators for effective evaluation of treatment performance, opportunity identification for improvement, reporting to the regulatory and the general public for ensuring accountabilities. With over 30 years' experience in the design and fabrication of environmental protective equipment, Qingdao Yimei Environment Project Co., Ltd understand the importance of performance monitoring in the success of a wastewater treatment.

Effluent Quality Parameters

Effluent quality describes the water coming out of a water sewage plant. Its main purpose is to minimize to below what are the allowable maximum concentrations per regulatory permits for a certain pollutant. Typical parameters for measuring effluent quality are: Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), total suspended solids, pH, and concentration of nutrients (phosphorus and nitrogen) within the wastewater.

BOD value reflects how much oxygen microorganisms inside the wastewater consume in order to decompose organic matters contained in the wastewater. The smaller the BOD value the better the plant’s organic pollution removal. Compared to BOD value, COD is an even more precise parameter as it measures the total demand of oxygen by all oxidizable matters contained in the water, including those non-biodegradable. TSS denotes the quantity of suspended matter contained in the water following treatment.

Nutrient removals are being recognized increasingly important as high nutrient concentrations within wastewater could cause eutrophication within water bodies. In effect, some existing permits contain already quite tight restrictions over nutrient removals because receiving water bodies are very sensitive to nutrients. Qingdao Yimei Environment Project Co., Ltd's advanced wastewater treatment equipment has biological and physical treatment process for promoting the nutrient removals.

Hydraulic Performance Indicators

Wastewater treatment plants efficiency can be measured through a number of hydraulic performance indicators. Peak flow management, hydraulic retention time, and flow capacity.

Flow capacity is the highest allowable effluent quality which the plant could reach. The performance capability of the plant is mainly on processing a wide variety of influent flow rate, including season dependent ones. Municipal plants will receive large influent rate increase exponentially, for example, when there is heavy rain, and pose serious operation challenges.

Hydraulic retention time (HRT), is the amount of time wastewater stays inside the treatment system; the longer the retention time the better biological treatment effectiveness, and the more effective biological tanks. A crucial operational cost indicator lies on the trade-off between tank capacity and retention time. Qingdao Yimei Environment Project Co., Ltd Lamella Clarifiers, as their main product, have proved their ability of enhancing the hydraulic performance of a wastewater treatment plant for solids removal effectively within given space.

Solids Handling and Sludge Management Metrics

The list of some of solids handling and sludge management equipment can be considered as following. The solids handling performance indicator of a water sewage plant is too often neglected in an evaluation process. Thickeners, dewatering equipment and disposal strategies all constitute integral part of sludge treatment operation performance and operating cost.

Some important indicators of performance are solids concentration of the sludge following thickening process; cake solids concentration after dewatering; solids removal by digestion process (or volatile solids removal); the quantity of polymer needed per ton solid to pre-treat the sludge; With the help of operating mode as proposed here for sludge treatment system operation, the disposal of sludge and the transported volume of sludge will decrease and the operating cost will decline as well.

Using Screw Dehydrators from Yimei has demonstrated ability to deliver the sludge cake solids with high concentration and low power consumption and therefore, enables the cost effective waste sludge management. Qingdao Yimei Environment Project Co., Ltd Lamella Clarifiers are used in sludge thickening processes and will increase the performance for solids removal as well.

Energy Efficiency and Operational Cost Metrics

Energy performance indicators are defined and measured in a wastewater treatment plant and are correlated with operating costs. As a major operation expense is usually energy consumed by the treatment plant, operational energy indicators may assist operators in finding out what is needed to be improved and the sustainability of plant operation.

Energy intensity is measured by specific energy consumption (sec), which is energy per unit volume of wastewater treated. One of the most critical operational energy factors is the energy consumption in aeration processes which may be as high as 40~60% of total energy. Optimizing the blower system, employing fine bubble diffusers and variable frequency drives are one of methods for substantial energy savings.

Chemical use costs, manpower costs, and maintenance costs are also among important operational cost indicators and should be monitored, especially to enable trend evaluation and for effective plant comparison and continuous improvement.

Conclusion

Performance of a water sewage plant should be evaluated based on the indicators, including effluent quality, hydraulic performance, solids handling performance, and energy performance. These indicators are all crucial for regulatory compliance, capital project planning and operation efficiency improvement. Because of the difficulty in wastewater treatment and following need for stable and efficient sludge disposal, Qingdao Yimei Environment Project Co., Ltd can provide a comprehensive series of equipment for wastewater treatment and sludge disposal.