CITY OF YUMA WASTEWATER TREATMENT PLANTS. Cactus Moon Education, LLC.

Transcription

1 CITY OF YUMA WASTEWATER TREATMENT PLANTS

2 Wastewater Purify Processes Environment Influent Landfill Bacterial Micro-organism Biological Clarification Residual Anaerobic Methane Bio-Solids Vocabulary

3 All the wastewater (water from washing machines, toilet flushes, dishwashers, garbage disposals, baths and showers etc.) that is put into the city sewer system goes to either the City of Yuma Figueroa or the Desert Dune Water Treatment Plants. The treatment of the wastewater involves several processes, or steps, to purify the water and the biosolids, so they can be returned safely to the environment. This presentation will explain the steps that the City of Yuma uses at the Figueroa Wastewater Treatment Plant.

4 How It Starts The wastewater entering the Figueroa Waste Water Treatment Plant is called Influent. Influent is the liquid waste or raw sewage from homes and businesses that goes into the sewage collection system and enters the Waste Water Treatment Plant to be cleaned.

5 Step 1 Influent Screening When the influent arrives at the Figueroa WWTP, it initially goes through Bar Screens which remove large solid objects. From time to time mechanical rakes drag the solid objects out of the Bar Screens and convey them to a collection area ready to be transported to a landfill.

6 STEPS 2 AND 3 - GRIT REMOVAL AND PRIMARY SETTLEMENT After the heavy materials have been removed at the Bar Screens, the wastewater goes to Settling Basins where the small, heavy particles such as grit and sand sink to the bottom. The grit and sand are collected and transferred to a landfill. Once the grit and sand have been removed, the sewage is transferred to the Primary Settling Tanks. Here, most of the solid material settles to the bottom and oils and grease float to the surface. A skimmer removes the scum, grease and oil that float to the top, and these and the settled solids are sent to the Digester Tank. The wastewater then goes to the Aeration Tank.

7 STEP 4 - AERATION TANKS In the Aeration Tanks large amounts of air are bubbled into the mixture of wastewater, bacteria, and other micro-organisms. The microorganisms remove organic material that is dissolved in the wastewater. Enough oxygen is supplied by the air to support the biological process at a very active level. The ratio of organic matter to organisms to oxygen is continually monitored and adjusted to meet the daily variations in the wastewater make up.

8 STEP 5 SECONDARY SETTLEMENT In this Secondary Settlement clarification stage, more solids settle out of the water. Some are returned to the Aeration Tank to help maintain the quantity of micro-organisms, and the rest are sent to the Digester Tank (See Step 8). One final step is required before the water can be safely returned to the environment.

9 STEP 6 DISINFECTING Finally, Chlorine is added to remove any harmful microorganisms that might be in the water. Care must be taken to ensure that no residual chlorine is in the water prior to it s discharge into the environment.

10 STEP 7 DISCHARGE TO THE ENVIRONMENT The cleaned water can now be returned to a local river, steam, or aquifer.

11 STEP 8 SOLID DIGESTION The solid material that is collected so far is pumped into a Digester Tank where more microorganisms convert the solid material into methane and bio-solids in an anaerobic atmosphere. The methane can be flared or used as a fuel for heating or for making electricity. The bio-solids can be sent to landfills or used as a fertilizer.

12 Waste Water Treatment Plants (WWTP) 1 Raw sewage enters the treatment plant and passes through bar screens that remove large, solid objects Grit is allowed to settle out of the sewage and is removed to a landfill Most of the solid material settles out in the Primary Settlement Tank while oils and greases float to the top. The solids and greases are collected and sent to the Digester Tank. 4 Micro-organisms consume the remaining organic matter in the Aeration Tank. 5 In the Final Clarifier more solids settle out of the water. Some are sent back to the Aeration Tank to help supplement the micro-organism population. Other solids are sent to the Digester Tank. 7 8 In the Digester, more microorganisms convert the collected solid material into methane and bio-solids Finally, chlorine is added to remove any harmful microorganisms. The water is now clean enough to be discharged into rivers or streams. 9 Methane can be used as a fuel for heating or to make electricity. 8 Bio-Solids can be sent to landfills or used as fertilizer.