Joint Water Pollution Control Plant

(A numbered step explanation of the Process Flow Diagram)

The Joint Water Pollution Control Plant (JWPCP) is operated by the Sanitation Districts of Los Angeles County. The JWPCP is one of the largest wastewater treatment plants in the world. This is why I chose to use this particular plant for our space station. It serves a population of over 3.5 million people, and many industries in southern and eastern Los Angeles County. This particular plant can manage to provide for many people on the space station, as it provides water treatment for 350 million gallons of wastewater per day in the Los Angeles County. The end result is fresh, clean water, with the waste going to farms as composting materials and the water to homes and seas on our space station.

Wastewater Treatment

1. The preliminary treatment process removes large debris from the incoming wastewater of the sewers with barscreens.
2. This material is ground into a smaller size to protect equipment in the treatment plant and is then returned to the incoming flow. Each day, 15 tons of grit and sand are removed in the grit chambers in this water treatment process. This feature of the treatment process lets the dirt and grime settle at the bottom of these tanks which go to the digesters. Polymer is added at the grit chambers where it is mixed with the wastewater to enhance settling in the primary settling tanks.

Advanced Primary Treatment:

3. The settled solids, also called sludge, are pumped with the floatable materials to digestion tanks for further treatment. The remaining wastewater is split into two streams. One stream receives secondary treatment while the other is sent through fine mesh traveling screens to remove any grease or floating particles that remain.

4. After removal of the solids in primary treatment, a portion of the wastewater receives secondary treatment. Bacteria in the secondary treatment process, consume the organic material remaining in the wastewater.
1. In the large reactors, the bacteria use pure oxygen which is generated by an on-site cryogenic system. The clean water and bacteria are sent to secondary settling tanks.
2. The bacteria settle to the bottom, leaving clarified water at the surface. Some of the bacteria are returned to the reactors and the remainder go to the digestion tanks.

7. The treated water is disinfected with chlorine in order to meet bacteriological standards in the sea which protect the swimmers. The combined flow will then be sent to the homes and seas on our space station through underground pipes.

Solids Processing

8. The solids captured by advanced primary and secondary treatment are sent to digestion tanks where bacteria feed on the organic material and produce methane gas.
1. After digestion, the solids are centrifuged (a spin dry process) to remove as much water as possible. Polymer is added to help in the dewatering process.

Biosolids Use and Disposal:

The digested, dewatered sludge produced by the centrifuges is a valuable source of nutrients and organic material called biosolids. The biosolids can be hauled by truck to several sites for use in composting or for disposal. Some can be composted to produce soil which can be used in agricultural land to fertilize and condition the soil. Some can also be taken to the landfills on our space station. The biosolids are biodegradable and can produce methane gas, which can be used as a fuel in a combined cycle power plant.

Combined Cycle Power Plant

The methane gas produced in the digestion tanks will be used to fuel a combined cycle power plant which generates electricity for plant equipment and steam for digester heating. The power plant allows us to be self-sufficient and will even be able to produce surplus electricity for our space station sufficient to power approximately 1,500 homes.