How it works
A marketplace that owns the whole transaction
Seed Sludge is more than a listing board. We run the testing, the trucks and the money. That's why we can promise neither side gets cut out.
The problem
Seed sludge has been traded by phone call and favor
When a plant commissions a new digester or a digester sours, operators call around to other plants. When someone agrees, the buyer still has to find a hauler willing to move live biosolids, guess at quality, and hope the seed is still active when it arrives.
Sellers have it no easier. Surplus digestate usually goes to land application or disposal, even though it's worth more to a plant that's starting up. Giving it away informally means taking on liability, phone tag, and trucks showing up unannounced.
Disintermediation protection
We own the transaction so neither side gets cut out
In most two-sided marketplaces, buyer and seller swap phone numbers on the first deal and skip the platform after that. That undercuts the logistics, testing and insurance that made the first deal safe. It also leaves the platform without the revenue it needs to keep offering them. Here are the five ways we prevent that, plus the reason you won't want to go around us.
- 01
Identities are masked
Listings show an anonymized facility description ("Municipal WRF · 38 MGD") and the nearest metro, never the plant name, operator or street address. Buyer requests are masked the same way.
- 02
Pre-deal messages are relayed and scrubbed
Questions go through Seed Sludge. Phone numbers, emails and links are removed automatically before the other side sees them. You can ask anything technical, but you can't swap contact details.
- 03
Contacts unlock only when the deal locks
When the buyer accepts a quote and places a 20% deposit, both sides see each other's full contact details at the same moment. That's when you need them to coordinate loading and site access.
- 04
We hold the money
The deposit and balance go through Seed Sludge escrow. The buyer pays only for seed that arrives as described, and the seller is paid when the buyer signs off on delivery. Neither side carries credit risk.
- 05
Non-circumvention, both directions
Locking a deal means agreeing that for 24 months, further seed transactions between the same two parties are booked through Seed Sludge. The clause binds buyer and seller equally.
- 06
Why staying is worth it
Repeat orders keep the platform's vetted hauler, pre-ship lab panel, cargo insurance, chain-of-custody records and dispute handling. Doing it yourself puts that work and that risk back on your own crew.
For buyers, this means
- • A seller can't take your deposit and sell the volume to someone else
- • Lab results are independent, not seller-reported
- • A full refund if the pre-ship panel comes back out of range
For sellers, this means
- • No unsolicited calls or trucks before a deal is real
- • Guaranteed payment once delivery is signed off
- • Insurance and paperwork handled, so your liability stays limited
Logistics & testing
How every load moves
Each quote picks equipment from your volume and distance. For runs over 250 miles we recommend refrigeration to slow biological activity and gas build-up so the seed arrives viable.
| Mode | Per truck | Rate (loaded mi) | Per-load fixed | Best for |
|---|---|---|---|---|
| Lined vacuum tanker | 6,000 gal | $4.25 | $375 | 3,000+ gal, < 250 mi |
| IBC totes on flatbed | 4,400 gal | $3.10 | $200 + $95/tote | Small volumes, granular sludge |
| Refrigerated trailer (totes) | 4,400 gal | $5.60 | $325 + $95/tote | Long runs > 250 mi |
Use seller's recent lab results
$0
- • Only available when seller results are under 30 days old
Standard pre-ship panel
$425
- • TS / VS
- • pH
- • Alkalinity
- • VFA : Alk ratio
- • Fecal coliform (MPN)
Extended panel + activity
$1,150
- • Everything in Standard
- • Salmonella sp.
- • Part 503 metals
- • Specific methanogenic activity (SMA)
Fees
Simple, and paid by the side that gets the logistics
Sellers
Free to list. You set the seed price, and most municipal plants choose $0. You receive 100% of it on delivery.
Buyers
Seed + hauling + lab panel + a 8% service fee on seed and logistics (minimum $250). The fee covers escrow, cargo insurance, dispatch and documentation. Every quote shows every line.
Ready to try it?
Browse supply as a buyer, or list surplus as a seller. Both are free to start.