Little SBR SERIES – TREATMENT METHODOLOGY

(Hospital Wastewater)

June 2002

1. GENERAL:

ATS has considerable experience operating hospital wastewater treatment systems. The treatment of sanitary wastewater specifically generated from hospitals without blending from other domestic sources is much more challenging as compared to municipal wastewater facilities. The major differences between municipal facilities and stand-alone hospital treatment facilities are as follows:

A. Strength of both carbonaceous as well as nitrogenous waste per each person is much higher.

B. Occupancy or density of people per given space is extremely high.

C. Inorganic plastics, paper, metal items, and other waste items specific to hospital operations abound.

D. Pathogenicity including blood-born diseases are more prevalent than normal domestic sewage facilities, thus making hospital facility operations a higher risk safety factor.

2. SPECIFIC TREATMENT PROCESS:

Understanding the complications associated with the treatment of hospital wastewater, ATS has designed a unique treatment system focusing on safe and efficient operations. Based on semi-automated system integration, operation costs are kept to monitoring and data recording. ATS prioritizes its equipment efficiency and longevity. Being very selective of process components directly supports modest equipment system costs.

The Little SBR SERIES process is capable of treating small, medium, and large flows specific to hospitals and medical clinics. It provides the owner with a solution to every complication associated with treating hospital wastewater from removal of plastics, treatment of biological wastes, separation of solids from water, micron particle filtration, and final sterilization of effluent. The ATS process also addresses solids removal and de-watering to its final incineration.

3. PRE-TREATMENT:

Specialized pre-treatment devices (slotted static fine screens) are utilized to remove plastic gloves, needles, syringes, napkins, plastics, cardboard, cloth items, and a variety of paper-based products. Once these items, referred to as “trash”, have been removed incoming organics are dispersed into a splitter box, which distributes the flow evenly to biological treatment chambers called reactors. Flow entering these chambers is directed downward to the bottom of the reactor on one end. All water and food must enter the reactor from the bottom of the reactor tank. This helps to control any filamentous growth through rapid mixing of the activated sludge with fresh food (carbon) during the reactor fill cycles.

4. ADVANCED NITROGEN REMOVAL:

Significant concentrations of ammonia nitrogen exist in hospital wastes. The nitrogen being in an ammonia form directly causes water pollution and contamination. At hospital flow rates the ammonia must be converted to a more inert type of ammonia or removed altogether. The ATS Little SBR SERIES is designed to convert 100% of all ammonia nitrogen to nitrate nitrogen and, if need be, fully denitrify removing all nitrogen below 10 mg/l.

5. PRINCIPLES OF NITROGEN CONVERSION:

The process of removing nitrogen depends upon removal of carbon waste sources. Nitrogen removal is achieved by operating the biological process in a very old sludge age condition whereby forced starvation conditions are created. This ensures that that carbon up-take is rapid in both the Heterotrophic and Autotrophic phase. The ATS Little SBR SERIES treatment process is a wonderful advancement from standard type SBR technologies where, in a simplistic manner, both biological conditions are promoted at the same time in the same tank. In some ATS systems this may also be allowed to occur while the tank is being hydraulically loaded at the same time.

6. DENITRIFICATION:

Denitrification (complete nitrogen removal) can be achieved during normal SBR sequencing. However, this particular cycle is carbon-dependent and fairly often requires some form of chemical supplementation to obtain 100% total nitrogen removal.

Anoxic and aerated mixing occurs while the reactor is filling. When the water has reached a given elevation, mixing and aeration are terminated. The reactor is allowed to settle for 60-70 minutes. During this time and depending upon conditions, incoming wastes may be permitted to enter the reactor. After the completion of settling, supernatant 6” under the surface is decanted for about 70 minutes or less. At the end of the supernatant decant cycle, a prescribed volume of sludge is removed or wasted out of the reactor to a sludge storage chamber called a digester. During the cycles above, no aeration or mixing of sludge has occurred and dissolved oxygen concentrations are purposely allowed to decline into anoxic conditions. At this point with dissolved oxygen levels ranging from 1.0 ppm down to .6 ppm the submersible aerator/mixer(s) are activated with the air induction feature turned “off”. Anoxic mixing distributes the new carbon based food throughout the entire reactor.

With dissolved oxygen levels low the carbon acceptor (food) has now been provided to allow the final conversion of nitrogen-to-nitrogen-gas to occur. The gas is then released into the atmosphere during the re-aeration portion of the reactor fill cycle. Aeration is re-started automatically and critical dissolved oxygen levels are restored. When water has re-filled back up to the batch start level in the reactor (LC1) a new batch begins again.

7. DECANTING & PRIMARY DISINFECTION:

At the completion of the settling cycle clear water above the settled sludge is drawn off by means of a specially designed ATS floating decanter pump unit. The clear water is injected with liquid chlorine providing initial disinfection to begin the process of removing pathogens prior to effluent polishing. The water containing chlorine is transferred into a tank referred to as a chlorine contact chamber and allowed to stay there for a minimum time period of 60 minutes. During this time period chlorine disperses throughout the tank ensuring long-term contact with pathogens.

8. EFFLUENT POLISHING: (Filtration)

Removal of residual small suspended solids is required in order to remove residual organics which otherwise would extract oxygen out of the receiving stream or discharge area. Also, it is critical prior to final disinfection that as many particles as possible are removed. Removal of small particles is accomplished by direct media contact sand filtration. A unique self-operating sand filtration system is provided to accept the flow of water from the contact chamber at a flow rate which ensures the contact tank to be empty prior to the next batch. The filter unit backwashes itself automatically ensuring fresh media is always utilized for particle filtration. Backwash from the filter is directed back to the splitter box located at the head of the treatment plant for re-distribution and

re-treatment through the reactor(s).

9. EFFLUENT STERILIZATION:

Prior to discharge the treated water must not contain any pathogens. In order to achieve this, water leaving the filtration system is exposed to Ultra-Violet light at a prolonged time period to ensure that remaining pathogens are killed. The U.V. system is unique in that through a self-cleaning procedure maximum U.V. exposure is provided. The U.V. sterilization is achieved in closed stainless steel constructed U.V. housings keeping all water contained.

10. SOLIDS YIELD & DEWATERING:

Creating a bio-solids yield is part of any well operating and designed wastewater treatment facility. If not kept in check, solids production would begin to carry over to the chlorine contact chamber causing more chlorine to be in demand plus posing problems for downstream process equipment.

A prescribed amount of solids is removed automatically from the reactor(s) on a batch- by- batch constant and continuing basis. Systematic solids control maintains even solids inventory inside the reactors, which also enhances the best and clearest water quality possible. The solids wasted are directed to the solids digester chamber. Solids inside the digester chamber are kept under periodic oxidation keeping the aerobic process active. Once every day a prescribed amount of solids is automatically pumped out of the digester to a filter press system, which extracts the water from the solids under pressure.

The filter press operates in a closed contained system, which is designed to minimize human contact for personal safety purposes. The de-watered solids form a semi-dry cake, which is then removed from the filter press and disposed of. Extracted water from the filter press is sent directly back to the head of the treatment plant for re-processing. The filter press is used on a daily or every–other-day basis thus keeping up with the continuing bio-solids development in the reactors.

11. SOLIDS DISPOSITION: (Incineration)

Bio-solids cake from the filter press is pathogenic and must be prevented from coming into contact with environmental resources such as ground water, rivers, streams, lakes or land or property exposed to any form of non-contained rain run-off. This includes any area that has public access contained or non-contained. The safest way to dispose of all treatment system wastes is through incineration.

Screened trash debris from the pre-treatment slotted fine screens contained in dumpsters is also incinerated using the same incinerator, providing an overall “complete treatment system concept”. ATS provides a waste disposal incinerator sized specifically to burn the amount of projected waste material as sludge and trash. The incineration unit is a stand-alone device not designed to assist the hospital with its medical incineration needs. Ash generated from the incinerator is finally safe to be disposed in an approved sanitary landfill.

12. PROCESS CONTROLS:

The entire process is controlled and monitored by a computer-based software program which permits internet access for viewing and possible long distance control assistance by the owner’s technical representatives.

13. TREATMENT COMPLETION:

Once sludge has been incinerated and ash removed plus fully treated and sterilized effluent leaves the Little SBR SERIES process as described above, a full and complete treatment solution exists. Without each and every step detailed above, pathogenic contamination or pollution risk to the public will exist. That is the key in treating hospital specific wastewater. No one step must be overlooked in order to protect public health and safety. The ATS Little SBR SERIES process serves this need.