Date post: | 14-Apr-2017 |
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Environment |
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HOW REMOTE TOILETS WORK (OR FAIL TO)And what they should really be doing
Geoff Hill, PhDSustainable Summits Conference Golden, CO
Waterless Toilet Overview Comparison
Elbow Lake, ABCampground, open 3 months per yearUse/yr: 50002 stall - 2 Composting ToiletsAnnual O&M cost: $2660O&M Freq: weeklyCost per use: $0.53OSHA Exposure Events/yr: 33Material removal: every year (dump)
Faverges, FranceRoad Side, open 12 months per year
Use/yr: 200001 Stall – Urine Diverting + Vermicomposting
Annual O&M cost: $700O&M Freq: yearly
Cost per use: $0.035OSHA Exposure Events/yr: 3
Material Removal: every 10-20 years (dump)
Outline• Waste Paradigm• Compost – what it actually is• Remote Site Challenges• Types, Objectives, Evaluation of Remote Toilets• Human Waste Composition & Production• Source Separation• Urine Diversion• Performance of Urine Diversion vermicomposting toilets• Future Direction
Flush Toilet• Homes in the Western world
• Water (cheap / limitless)• Power (cheap / limitless)• Onsite labor (cheap, home owner)• Nutrients needs (garden, lawn)• We FLUSH it away
• Waste Management Paradigm• Toilet #1 invention for human health• Water as vehicle – everything removed at WWTP
Compost from biosolids in USA• Biosolids extracted from WWTP – burned, land applied, or
composted• Public operations are held to EPA 503 rules, thermophilic
engineered process for degrading and sanitizing waste• 5 turns in 15 days, >55C, fecal coliform testing to assure process,
• Very rigorous and challenging• Done at centralized facilities
• Still very difficult to make profitable and worthwhile
Remote sites• No power / solar power• No water • Limited / expensive labor• Cold• No use for nutrients or organic
matter
Types of Toilets at Remote Sites• Pit
• Dig hole (6-10’ deep), fill up, cap, dig another.• Composting
• Buy unit, users add wood, ‘service’ weekly, blackwater leaches, dump solids onsite yearly (or pack-out)
• Vault (concrete or plastic barrel)• Buy precast unit, pump yearly, remove to WWTP
• Incinerating (very few – private)• Urine Diverting Vermicomposting (France)
• Not covering dispersed• Pack-out• Cat hole
Objective of These Toilets• Pit
• Lowest cost regardless of human health & environment• Composting
• Make compost, regardless of O&M cost & safety• Vault (concrete or plastic barrel)
• Least environmental impact, safety, O&M cost• UDVCT
• Lowest life cycle cost O&M, acceptable environmental impact, and high health & safety standard
Pits• Pits can be found years later – no
decay • Many toilets dug into ground water• With 1m unsaturated soil
• Viral pathogens can travel 3000m• Hepatitis A, Polio, Astrovirus, Calcivirus,
Rotavirus, Norwalk, Coxsackievirus, Echovirus
Sources:WHO Funded: “Guidelines for Assessing the Risk to Groundwater from On-Site Sanitation”, British Geological SurveyMoore, C., 2010. Institute of Environmental Science and Research (N.Z.) Staff. Guidelines for separation distances based on virus transport between on-site domestic wastewater systems and wells. ESR Communicable Disease Centre, Porirua, New Zealand.
Pits• Treatment paradigm
• Not effective• Dumps in our parks?
• Waste Management Paradigm• Not safe• Virus travel very far• Very hard to detect (few labs culture viruses)
• NPS – should all be replaced• With…..
Composting toilets• Don’t compost shit at home…
• Why compost shit in the woods?
• Tried to failure dozens – hundreds of times
Composting toilets (CTs): a misnomer• PhD + 5 peer review publications
• 4 brands, 12 sites, 16 chambers, 100+ samples
• 0/16 chambers pass NSF Standard 41• 0/16 processes meet EPA 503 regulations
• None heat up more than 10C above ambient• 0/100 samples meet definition of compost
• Stability, maturity, smell• Raw fecal matter no different from CT end-
product (E.coli, volatile solids, stability)• All continuous flow
• Effective residence time: 1-2 days
6yr old ‘compost’
2 outcomes• Ammonification toilet
• Primarily urine – ammonia & pH escalate – inhibits all life• Not effective enough to reliably sanitize• Many campgrounds and trailheads
• Pathogen brew pot• Primarily fecal matter• UBC CK Choi – Flagship of composting toilets, maintained by paid
personnel every day.• >100,000 E.coli in 5yr old material (E.coli breeding ground)
Composting Toilets as Waste Management (typical 3000 user site)• $2665/yr to maintain• 33 occupational exposure events / yr (face close to
fecal)• Effective?
Vault Toilets - Barrel• True waste management perspective• Terribly expensive and hazardous to operate• $0.30 to $1.00 per use• Requires an operator to change barrels
Human Waste Production / Composition
• Urine• 160-200ml per use• 80% of plant nutrients (NPK)• Zero heavy metals• Zero pathogens • Self sanitizing (storage)• Flows by gravity
• Fecal matter• 80-100g per use• 20% of plant nutrients• 100% of heavy metals• 100% of pathogens (106-8bacteria,
helminth, viral, protozoan)• Doesn’t flow
Source Separation• For maximum value & least cost ‘waste management’• Waste Management BMP• Lets apply to wilderness waste• Human waste = urine + fecal (2:1)
Urine Diverting Vermicomposting (UDVCT)
• Ecosphere Technologies & Ecodomeo (France)• No bulking agent
UDVCT
End-Product Waste Management
Stable – Very Stable O&M costs/yr = $273
No odor Exposure events/yr = 3
<200 CFU/g E.coli Dry matter reduction = 40%
Lots of trash Emptied every 10-20 years
UDVCT vs CTUDVCT CT Comparison
O&M costs/yr = $273 $2665 10x
Exposure events/yr 3 33 10x
Dry matter reduction -40% +300% Almost 10x
Disposal Emptied every 10-20 years
Every 6mo – 2 yrs
5-20x
E.Coli <200CFU/g 104-106 CFU/g 100x lower
North American Implications• Step 1: divert urine
• Gravity manage to septic field 66% of daily mass• Step 2: don’t add bulking agent• Step 3: look and see what’s eating local horse manure
(naturally source separated) and put it into fecal matter & toilet paper
• Step 4: don’t touch the poo, leave it for as long as possible
• Step 5: budget a decadal line item for removal and disposal
Step 1: Divert Urine (the hard step)• Behavior• Ecovita seat – private only• Mechanical (Toilet Tech Solutions)
Behind-the-Wall + Pedal Power Below-The-Floor + Door Power