Aerzen's AERprocess dissolved oxygen control is an integrated solution for controlling DO concentration and blowers in an activated sludge...
System requires no electricity, treats 1,000 liters per day in West Bengal
With estimates of more than 100 million people in West Bengal, India and neighboring Bangladesh at risk of consuming arsenic contaminated groundwater, arsenic poisoning has become a disease of epidemic proportion, which some experts are calling the "largest mass poisoning in history." The problem exists to a lesser degree in many other countries of the world that also depend on contaminated groundwater for potable water consumption.
The origins of this outbreak began in the early 1970s, when government health officials identified the consumption of disease carrying surface water as the cause for an alarming number of cholera and dysentery related illnesses. To alleviate the problem, local villages, the United Nations and the government of West Bengal installed a large number of tube wells that supply subsurface water, uncontaminated by human and animal use, to rural communities. With the unfair advantage of hindsight, officials now realize that many of the tube wells throughout India and Bangladesh retrieve drinking water from strata containing high levels of naturally occurring and extremely soluble arsenic. Testing performed by India’s Public Health Engineering Directorate (PHED) and The World Health Organization (WHO) indicates that water from these tube wells contains arsenic in dangerously high levels, often in excess of 1.000 mg/L. Within West Bengal alone, it is estimated that 16,000 tube wells contain arsenic levels greater than 0.050 mg/L and that over 3 million tube wells in the subcontinent have levels considered unsafe by WHO whose recommended levels are less than 0.010 mg/L.
The health effects of these high levels are frightening. Currently in Bengal, more than 200,000 people suffer from some degree of arsenic poisoning, with the bulk of symptoms expected to appear in the next five to ten years.
Solubilized in water, arsenic exists in the form of both arsenite and arsenate. Arsenate, the most common form, is quickly absorbed by the human body and has lethal effects. Long-term, high level arsenic exposure will cause symptoms including thickening and discoloration of the skin; lesions; stomach pain; nausea; vomiting; diarrhea; loss of limbs, cancer of internal organs; and neurological disorders that precipitate tingling and numbness in the extremities, hearing impairment, and developmental effects.
Symptoms of arsenic poisoning or arsenocosis, usually begin to appear within five to 10 years of consumption, with fatality becoming imminent after 15 to 20 years of exposure. Compounding upon the physiological impairments is the social isolation experienced by those suffering from the disease. Women with visual symptoms of the disease are often refused by their husbands and cut off from family, in effect segregated from the remainder of the community.
Few if any low cost technologies exist to address the magnitude of this problem. Conventional methods for removing arsenic from water, which include adsorption, iron/manganese removal processes, co-precipitation, ion exchange, and membrane processes, often cannot meet the requirements mandated by the regions numerous remote locations and limited financial resources. As such, a recognized need exists to develop an affordable technology, which could be applied in remote areas, operate with no electricity, require no chemical addition, and be simple to operate and maintain.
In answer to the challenge, Apyron Technologies, Inc. has developed a new low cost technology for purifying arsenic contaminated groundwater that can assist the government of India in removing this slow but steady assassin from their midst. The Apyron has designed an integrated treatment system (patent pending) to meet the needs of the region and is easily adaptable to the rural setting, requires no electricity, is effective under a wide range of water chemistry applications, and is extremely cost effective with ongoing operational costs averaging 4 cents per family per day.
A key component to the system is Apyron’s Aqua-Bind; Arsenic technology, a proprietary alumina-based adsorption media that can selectively remove the two most common forms of arsenic, arsenite (As+3) and arsenate (As+5) from water. Applying its unique binder technology, which allows systematic manipulation of the surface properties and creation of a composite particle, Apyron has been able to create an adsorbent material with unique surface, pore properties and chemical characteristics enabling arsenic adsorption capacities up to five times greater than conventional materials.
The selective capabilities of the media permit the high adsorption capacities, even in the presence of competing ions, which significantly extends the media life and reduces maintenance cost. Adsorption kinetics are also very rapid, allowing efficient removal of arsenic, often to levels below laboratory analytical detection limits. Another key feature is that due to the aggressive contaminant binding, the spent material has been tested to be nonhazardous per USEPA TCLP standards.
To prove the efficacy of the Aqua-Bind Arsenic technology for purifying contaminated groundwater, Apyron performed two major field demonstrations in India. In early 1998, Apyron deployed a gravity fed, field prototype unit in West Bengal utilizing its patented granular Aqua-Bind Arsenic XP media. The unit operated successfully for three months, treating an estimated 60,000 liters of water (approximately 700 liters per day) at the rate of 2 gpm. During this testing, Apyron became aware of the wide variations in groundwater chemistry and the need to address high concentrations of dissolved iron and arsenic. Arsenic levels of up to 400µg/l were successfully removed to below 0.01mg/l during this demonstration.
A second field test was conducted in August 1999 with a new modular system designed to address high concentrations of both iron and arsenic, which often coexist. The system treated approximately 1,300 liters/day with influent arsenic concentrations as high as 900µg/l and iron concentrations as high as 10mg/l. Effluent water levels after purification through Apyron’s unit were consistently below the recognized treatment goal of 0.050mg/l arsenic and iron, meeting the treatment standards acknowledged by the PHED.
Capitalizing on the data from these demonstrations and incorporating performance criteria provided by the PHED, Apyron has optimized the media composition and housing design of its Arsenic Treatment Unit (ATU) for use in India. Delighted with the cost effectiveness of the system as well as the operational simplicity of the unit, the PHED requested in February a proposal from Apyron’s Indian Joint Venture for an initial order of several thousand units to include installation, operation, and ongoing maintenance. The proposed system, which will operate for six months before requiring a change in media, is designed to treat 1,000 liters of water per day with influent levels of arsenic averaging 250µg/l and iron of up to 15mg/l.
The unit, operating with a flow rate of 12 liters per minute will be attached to a lift pump located at the tube well. The unit is equipped for backwashing that can be performed every two weeks to remove groundwater solids by the local villagers. Effluent water standards for the system were set by the PHED at less than 50µg/l.
Apyron president Dr. Leslie Story stated, "Apyron is excited about the opportunity to work with the PHED on eliminating this growing health crisis … We believe that in as little time as three months, the health benefits of our system will become evident, as the technology is deployed."
Arsenic treatment technology is also receiving greater attention in the United States, as the USEPA is preparing to lower MCL for arsenic below the current drinking water standard of 50 mg/l. Existing arsenic problems in public and private water supplies have been identified in a number of geographic regions of the U.S. The USEPA estimates approximately 2,000 public water systems may require additional arsenic removal capabilities once regulation is finalized in 2001.