WATER AND WASTEWATER TREATMENT
Just like fresh air, water is an essential resource for the survival of humans and animals. Water constitutes 70% of the Earth surface but less than one percent can be classified as an accessible freshwater resource. Therefore, water is considered to be a scarce and most valuable resource in many regions worldwide. As an effort to preserve this scarce resource, chemical processing industries implement efficient water treatment processes to help maintain the quality of water. Furthermore, many chemical industries, along with developing technologies to improve water treatment, focus on process optimization and integration to reduce the overall usage of water in the plant.
There are two general applications to treat wastewater:
- Physical/Chemical Process
- Biological Process
Each process can treat a certain type of waste depending on its concentration in the water, its physical characteristics, and its required effluent concentration. Few of such processes are air stripping of VOCs, and bio-trickling filter.
Air stripping can be used to treat wastewater streams that contain less than 100 ppm VOC and insoluble organics such as methylene, chloride, and toluene. The process is designed based on Henry’s Law for dilute solutions, which is a function of temperature.
PA= Vapor Pressure of compound A (atm)
HA= Henry’s law constant of compound A
XA= Liquid phase mole fraction of compound A
Air stripping in a packed tower is compact and efficient. With different types of packing materials available, high efficiency is easily achieved. Air strippers are usually 15 to 60 ft tall and have diameters ranging from 1 to 10 ft. Air to volumetric ratio is in the range of 10 to 300.
Biotrickling filters make use of inorganic media in a large containment vessel to support microbial growth. Air is introduced at the bottom of the media with water distributed uniformly at the top to create a moist environment for microbial growth. Biotrickling filters work to reduce high sulfide concentrations without any media decomposition. New age, bio-trickling filter systems use plastic media to support aerobic activity. The high-density media is light in weight and can be stacked in vertical stages to reduce the footprint. The media is resistant to plugging and has a service life of 10 years.
Wet scrubbing is the technique used to remove acid gases, metals, and semi-volatile organic compounds (SVOCs) from a process waste gas stream. The removal of contaminants from the gaseous stream is often carried out over a packed bed where a suitable liquid (water or alkaline solution) is sprayed and contacted with the gas stream. A wet scrubbing system consists of ductwork and a fan system, saturation chamber, scrubbing vessel, mist eliminator, pumping, recycle stream, spent scrubbing liquid treatment and exhaust stack. A mist eliminator removes entrained liquid molecules from the gas stream leaving the system and therefore, an integral part of the wet scrubber.
MACH Engineering offers wastewater and air treatment solutions to help chemical industries achieve the regulation’s target. We design systems using Aspen Plus simulation software and other in-house proprietary software to satisfy our customer’s need. Also, we fabricate columns, provide tower internals and packing, and supervised installation to ensure that our designed system runs smoothly.