1. ARKANSAS RECYCLING COALITION
Alternative Sustainable Power
September 19, 2017
Session A
Walter B. Collins, P.E.
Director of Operations & Facilities

2. So how exactly is wastewater (sewer) treatment… recycling
So how exactly is wastewater (sewer) treatment… recycling and how on earth is it Alternative Sustainable Power..?? ?

3. So how exactly is wastewater (sewer treatment)… recycling
So how exactly is wastewater (sewer treatment)… recycling and how on earth is it Alternative Sustainable Power..??

4. So how exactly is wastewater (sewer treatment)… recycling
So how exactly is wastewater (sewer treatment)… recycling and how on earth is it Alternative Sustainable Power..??
There is Only One Water

5. This is clearly NOT a modern concept
Pont de Gard
Part of 50 km long aqueduct
Stands 50 m high
Spans 275 m across

6. This is clearly NOT a modern concept
Housesteads Roman Fort: A.D.

7. This is clearly NOT a modern concept

8. This is clearly NOT a modern concept
500 BC – Prosperous Chinese families had latrines in their houses
100 BC – Roman’s were building public toilets
124 AD – Housesteads Roman Fort (along Hadrian’s Wall) built with stone latrines
500 AD – Toilet paper developed in China (chopped mulberry bark and grasses)
700 AD – as China’s population grew, business opportunities developed for pay to use facilities – one stall mud huts
Prior to 1958 – City of Little Rock had direct discharge into the Arkansas River (downstream of the city)
1972 – Clean Water Act mandated specific wastewater treatment standards

9. What is modern is our method of reclaiming this water:

10. What is modern is our method of reclaiming this water:
We Grow Bugs…. Over 100,000 pounds

11. What is modern is our method of reclaiming this water:

12. What is modern is our method of reclaiming:
One of Three WRF for Little Rock
Average Daily 36 MGD reclaimed
Wet Weather Capacity 145 MGD
5,500 Tons of Biosolids
Non-biodegradable to landfill

13. What is modern is our method of reclaiming:
7.2 Million Gallons Anaerobic Digestion
deg F
15-20 day detention time
300,000 cubic feet biogas

14. What is modern is our method of reclaiming:
5,500 Tons of Soil Amendment Material
4N-3P-0.3K Nutrient Rating
Water holding potential

15. Alternative Sustainable Power:
Biogas Collectors
Biogas (methane):
300,000 cf per day
650 BTU/cf
<100 mg/L H2S

16. Alternative Sustainable Power:

17. Alternative Sustainable Power:

18. Alternative Sustainable Power:
Gas line filters
Pressure regulators
for both systems

19. Alternative Sustainable Power:
Tech-Jet gas mixing valves

20. Alternative Sustainable Power:
GE Jenbacher JMS 320:
480 volts nominal
1060 kW*hr
20 Cylinder
Dual fuel: biogas methane
and/or natural gas

21. Alternative Sustainable Power:
Original 1983 Eng/Get set:
18% gas to wire
545 kW*hr (3 units)
Jenbacher Eng/Gen set:
38% gas to wire
6,050 MW annually

22. Alternative Sustainable Power:
Paralleling Power Switchgear:
Fiber optic comm with local substation
SCADA Controlled to match plant demand
Primary source of power
Surplus power sold onto grid

23. Alternative Sustainable Power:
Protective Sensors:
900 internal checks
Engine timing (Lambda) changes to match biogas quality

24. Alternative Sustainable Energy:
Heat Recovery Potential:
Jacket water energy
Lube oil energy

25. Alternative Sustainable Energy:
Heat Recovery Potential:
Jacket water energy
Lube oil energy
Exhaust gas energy

26. Alternative Sustainable Energy:
Heat Recovery Potential:
Roughly 2 million BTU/Hr
Maintain digester temp: 95°F
Savings of $650/day

27. Alternative Sustainable Energy:
Supplemental Heat Potential:
Roughly 6 million BTU/Hr
Maintain digester temp: 95°F
Complete Eng/Gen shutdown
Dual fuel: biogas methane
and/or natural gas

28. Alternative Sustainable Energy:
Co-digestion of Industrial Wastes:
24,000 lbs of food grade waste
Population equivalent: 120,000
High energy source
Increases biogas production by 15%

29. In Summary: Combined Heat & Power: 300,000 cft biogas (650 btu/cf)
Roughly 2 million BTU/Hr heat
Approx 900 kWHr power
Plant demand ~ 800 kWHr
Parallel power production to grid
1 of 74 WRF (16,000 WRF)
Power savings $1500/day
Heat load savings $650/day

30. Thank You: Walter B. Collins, P.E. Director of Operations & Facilities
Little Rock Water Reclamation Authority