Upgrade & Retrofit Plan for the Food Waste Treatment Line

01 · WHY RETROFIT

Why retrofit this segment

The problem with the existing line is not the downstream oil extraction but the upstream task of "shredding the feed". Treating food waste with two-stage dewatering screws plus crushing and pressing essentially follows the kitchen-wet-waste mindset: squeeze the water out first, then proceed. This route carries three unavoidable costs.

Cost 1 · Wastewater

A separate effluent plant is required

Two-stage dewatering produces high-strength organic filtrate; together with wash water it must be separately collected and treated, requiring tanks, lift pumps, chemicals and sludge handling.

Cost 2 · Oil loss

Oil leaves with the water

Dewatering and pressing both squeeze out the liquid phase; grease passes into the water phase during this squeezing and draining, and a portion is already lost before three-phase separation.

Cost 3 · Blockages & downtime

Wrapping means shutdown

Crusher blades must be stopped and cleaned whenever plastic wraps around them; the press screw wears fast on grit and metal, wearing parts are replaced often, and an operator is needed every shift.

Current route: dewater first, then proceed

Feed is manually pushed into the bin, requiring a fixed operator
Twin-shaft dewatering screw (~3.5 m) + single-shaft dewatering screw, two-stage dewatering
The drained water must be collected and treated
Crusher is a separate step, prone to wrapping
Squeezer presses the material; press liquor re-enters the water phase
Heavy impurities directly impact the press screw

→

New route: pulp first, water stays in the system

Collection truck tips directly; hydraulic feed at bin bottom
Single-stage hydraulic pulping: shredding, pulping and sorting in one machine
Process water is recycled and topped up within the system; no effluent discharge
No crusher; on wrapping the machine reverses automatically and ejects it
No squeezer; the slurry is pumped directly to three-phase separation
Heavy impurities settle inside and are discharged continuously; light impurities are rejected continuously

The advantage in one sentence: turning the feed into a slurry fits the physical nature of food waste better than squeezing it dry. Slurry is a pumpable fluid; downstream oil extraction, grit removal and anaerobic digestion all rely on pumping, so dry feed is never needed. Building two-stage dewatering plus pressing just to obtain dry feed means first spending on equipment to squeeze out the water, then spending again on treating that water.

02 · CURRENT PROCESS

Current process as-is

Compiled from on-site accounts and your process flow diagram. The upstream dewatering, crushing and pressing are within this retrofit scope; the filtrate tank, cooking tank and dryer are reused as-is and are out of scope.

Existing upstream steps (segment to be retrofitted)

AS-IS

No.	Equipment / step	Current description	Issue
1	Feed bin	Material is manually pushed into the bin; ordinary discharge structure at the bottom	Requires a fixed post; labor-intensive
2	Twin-shaft dewatering screw	Two screws side by side, ~3.5 m long, trough with dewatering screen	Filtrate runs off; must be collected
3	Single-shaft dewatering screw	A single screw continues conveying and dewaters a second time	Further water loss; grease leaves with the water
4	Crusher	Separate crushing step that shreds the feed before the next stage	Plastic wrapping requires shutdown and cleaning
5	Squeezer	Screw pressing that expels excess water before discharge	Screw wears fast; press liquor is hard to treat

On-site photos · Before retrofit

6 photos provided by the client

Twin-shaft dewatering screw: two screw shafts in a trough, blades and screen fully coated with slurry and grease — **01Twin-shaft dewatering screw***Two screw shafts in a trough, blades and screen fully coated with slurry and grease*

Bin discharge: material cakes and bridges at the outlet, often needing manual poking to fall — **02Bin discharge***Material cakes and bridges at the outlet, often needing manual poking to fall*

Dewatering conveyor: the long trough leaks along its length, floor is wet and slippery, cleaning requires going to the trough side — **03Dewatering conveyor***The long trough leaks along its length, floor is wet and slippery, cleaning requires going to the trough side*

Squeezer: material builds up on the body and outlet, press liquor runs off and odors escape — **04Squeezer***Material builds up on the body and outlet, press liquor runs off and odors escape*

Crusher body: bearing positions leak, inlet is caked solid, wrapping requires shutdown and cleaning — **05Crusher body***Bearing positions leak, inlet is caked solid, wrapping requires shutdown and cleaning*

Feed hopper and screw: material coats the screw and hopper walls, conveying capacity drops month by month — **06Feed hopper and screw***Material coats the screw and hopper walls, conveying capacity drops month by month*

The above are on-site photos (only cropping and brightness adjusted; content unchanged). The common point is clear: as long as material is handled by "squeezing" and "pressing", equipment surfaces will inevitably scale, screen holes will clog and the floor will stay wet — this is not poor maintenance but a consequence of the process route. After the retrofit this segment becomes slurry pumping; dewatering troughs, screens and press screws no longer exist, and this cleaning work disappears with them.

Zaozhuang client · Site after upgrade & retrofit

On-site video after retrofit

CASE · ZAOZHUANG

Zaozhuang project · The same segment after retrofit

The Zaozhuang client’s original line was the same as yours: large grab feeding, two-stage dewatering, crushing and pressing. After the retrofit the upstream stage was merged into hydraulic pulping and sorting; collection trucks simply tip the material from their bins directly into the feed hopper, and no dedicated feed-pushing post is needed.

Dewatering screws, crusher and squeezer — four equipment sets decommissioned
Material becomes pumped slurry; troughs, screens and press screws no longer exist
The floor is no longer persistently wet; cleaning work is greatly reduced
Grease no longer leaves with dewatering and press liquor; oil yield rises

Video provided by the client on site; unedited.

Retrofit scope (included)

Items 2–5: four equipment sets decommissioned or removed
New hydraulic pulping & sorting machine, slurry pump and slurry piping/valves
Electrical control cabinet upgrade and interconnection with the existing system
Equipment positioning, foundation preparation and second-stage grouting
Water commissioning, loaded trial run and operator training

Retrofit scope (excluded)

Civil works, buildings, tanks and steel-structure modifications
Odor control system (interface available as an option)
Wastewater plant upgrade (this plan aims to eliminate wastewater entirely)
Power capacity expansion and water connection
Transport, lifting, and off-site disposal of old equipment

03 · PROCESS FLOW

Process flow: original / new

Drawn from the process flow diagram confirmed by your company. Yellow is the original flow (dewatering + crushing + pressing); orange is the new flow after this retrofit (hydraulic pulping + three-phase centrifugation); dashed yellow boxes are facilities shared with the current plant and not newly built.

← Swipe left/right to view the full comparison →

Original flow · currentDewatering + crushing + pressing

①Food waste truckCollected and delivered
②Feed binManual feeding, fixed post needed
③Twin-shaft dewatering screw~3.5 m, with dewatering screenremoved
④Single-shaft dewatering screwSecond-stage dewateringremoved
⑤CrusherSeparate crushing step, prone to wrappingremoved
⑥SqueezerScrew pressing, press liquor runs offremoved
⑦Organic residue → dryerDownstream step

Two side streams: filtrate and wash water → filtrate tank → cooking tank; press liquor re-enters the water phase, and grease is lost between dewatering and pressing.

New flow · after retrofitNo dewatering · no crushing · no pressing

①Kitchen waste truckCollected and delivered
②Hydraulic pulperShredding · pulping · sorting in onenew
③Organic slurryPumped; no dewatering or pressing
④Cooking tankShared with current, not newshared
⑤Three-phase centrifugeSeparates oil / water / organic residuenew
⑥Organic residue → dryerShared with currentshared

Inorganic residue (plastic, bones, etc.) → drummed off-site → incineration
Oil / water are split by the three-phase centrifuge: oil goes to the oil tank, water is reused in the process and no longer discharged.

About "tip it straight in": based on an existing case (the Zaozhuang project), before the retrofit it was also a large grab plus two-stage dewatering; after the retrofit the collection truck tips the material straight from its bins into the feed hopper, and the hydraulic feed at the bin bottom pushes it into the pulping main unit. No dedicated feed-pushing post is needed upstream. At the end of this section is a 720° panorama of the Liaocheng project after retrofit that you can drag to view the site.

04 · ITEM BY ITEM

Item-by-item

The left column is the current state and the right column is after retrofit. Every "saved" and "eliminated" corresponds to verifiable equipment sets, tonnage and electrical power.

Old vs new segment, item by item

12 items

No.	Item	Current (dewatering + crushing + pressing)	After retrofit (hydraulic pulping)	Change
1	Feeding method	Material manually pushed into the bin, requiring a fixed post	Collection truck (or grab) tips directly; hydraulic feed at bin bottom, no dedicated feeder	Labor -2 / shift
2	Dewatering stage	Twin-shaft + single-shaft screws, two-stage dewatering, ~3.5 m or more in total	Dewatering stage removed; slurry is pulped in the main unit at the process concentration	Equipment -2
3	Crushing step	Separate crusher; blades must be stopped and cleaned after plastic wrapping	Shredding is done once inside the pulper; on wrapping it reverses automatically	Equipment -1
4	Press dewatering	Screw squeezer presses the material; press liquor collected separately	Pressing removed; slurry is pumped directly to three-phase separation	Equipment -1
5	Process wastewater	Filtrate + wash water ~3 t/d, high COD; separate collection tank and treatment are mandatory	No process effluent discharged; process water recycled and topped up within the system	Wastewater eliminated
6	Impurity separation	After pressing, impurities are hand-picked; heavy impurities (grit, metal) easily damage the press screw	In-machine simultaneous separation: heavy impurities settle and discharge continuously; light impurities (plastic) are rejected continuously	No manual impurity sorting
7	Grease path	Dewatering and pressing carry part of the grease into the water phase; it is already lost before three-phase separation	Grease stays in the slurry phase throughout; no loss before three-phase separation	Oil yield ↑
8	Equipment sets	Bin + twin-shaft screw + single-shaft screw + crusher + squeezer = 5 sets	Hydraulic pulper + feed pump + three-phase centrifuge = 3 sets	5 → 3
9	Footprint	Long in-line layout; the screw section takes up most of the building length	Main unit is compactly arranged; the former screw length can become storage or QC area	~15 m of length saved
10	Odor control	Two-stage dewatering runs open; the filtrate tank is the main odor source	Fully enclosed operation; the main unit has a negative-pressure port that can connect directly to the existing odor system	Odor source eliminated
11	Wearing parts	Screw flights, dewatering screens and press screw wear fast; ~RMB 45,000/yr maintenance	Main unit is a single maintenance point; wearing parts are the knife set and screen; ~RMB 20,000/yr	Maintenance ↓RMB 25,000/yr
12	Power consumption	Dewatering 15 kW + dewatering 7.5 kW + crushing 22 kW + pressing 15 kW ≈ 59.5 kW	Pulping & sorting main unit 37 kW; net saving ~22.5 kW	Power -38%

"Nothing is used anymore" means specifically: the two dewatering screws are gone, the dewatering screens are gone, the crusher is gone, the squeezer is gone, the filtrate collection tank is gone, the wastewater lift pump is gone, and the daily chemicals and sludge handling of the main effluent plant no longer need to follow this segment.

DELIVERED CASE · 720° PANORAMA

Liaocheng · Food waste treatment plant upgrade & retrofit (delivered)

This is a full-line delivery of a similar retrofit project, with 18 panorama scenes you can switch through section by section. Press and drag on the image to look around 360°, scroll to zoom, and switch scenes by the labels at the bottom—— "no dewatering, no process wastewater" described above is exactly what the site looks like.

18Panorama scenes

12kTotal views

Full lineDelivery scope

Loading 720° panorama tour If it stays blank, the panorama failed to load; click "Open fullscreen in new window" at the bottom right

Scan to view the 720° panorama after retrofit
On desktop: www.720yun.com/vr/16fjermv5u4

Drag to rotate · scroll to zoom · switch stages at the bottom Open fullscreen in new window ↗

05 · SCOPE & PRICE

Retrofit equipment list & quotation

Rated for a single 20 t/d line. Equipment is supplied as a set, including transport to site, installation, commissioning and training.

I. Equipment

EQUIPMENTSubtotal RMB 703,000

No.	Equipment	Model / spec	Qty	Unit	Unit price (10k RMB)	Notes
1	Hydraulic pulper core unit	ZSGJ-3 (20 t/d class)	1	pc	25.80	Crushing, pulping and sorting in one; replaces dewatering, crushing and pressing in a single stage
2	Three-phase centrifuge new oil extraction	WLL-400	1	pc	32.70	After heating, splits the slurry into oil, water and residue; the oil phase goes to the oil tank
3	Three-phase feed pump	G40-1	2	pc	1.10	One duty, one standby; stable feed pressure
4	Slurry pump	ZJB-7.5	1	pc	1.40	Positive-displacement pump conveying 8–12% solids slurry; resists clogging
5	Inorganic residue collection & drumming	Hopper + screw + dustbin	1	set	1.80	Plastic, bones and other inorganic residue discharged continuously, drummed off-site for incineration
6	Slurry piping & valves	DN100 quick-connect	1	set	2.60	Piping, valves and quick couplings from the main unit to the three-phase section; 304 stainless steel
7	Electrical control cabinet (extension)	Interfaced with the existing system	1	set	3.80	New main-unit and three-phase circuits and interlocks; existing control logic preserved
	Equipment subtotal				70.30

II. Engineering & service

SERVICESubtotal RMB 58,000

No.	Item	Spec	Qty	Unit	Amount (10k RMB)	Notes
1	Equipment positioning & foundation prep	—	1	item	2.20	Positioning, alignment and second-stage grouting of main unit, centrifuge and pumps
2	Piping, wiring & insulation	—	1	item	1.90	Slurry, hot-water and oil piping and electrical wiring, including pipe insulation
3	Commissioning, trial run & operator training	—	1	item	1.70	Water and loaded commissioning, parameter tuning; operation and maintenance training for 2 personnel
	Engineering & service subtotal				5.80

Total retrofit investment

76.1010k RMB

Including equipment, installation, commissioning and training · incl. 13% VAT

EquipmentRMB 703,000
Engineering & serviceRMB 58,000
Rated capacity20 t/d
Investment per t·dRMB 38,000 per (t·d)
Annual benefitRMB 574,400
Static payback15.9 months

Comparison with original value of replaced equipment

Replaced equipment	Spec	Original value (10k RMB)
1	Twin-shaft dewatering screw	~3.5 m, with dewatering screen	15.50
2	Single-shaft dewatering screw	With dewatering function	9.80
3	Crusher	Separate crushing step	11.50
4	Squeezer	Screw press dewatering	17.80
Original-value subtotal of old segment		54.60

Deductible item: if the site already has usable three-phase separation equipment with spare capacity for the new line’s slurry, the centrifuge and feed pumps can be deducted by RMB 349,000, lowering the retrofit investment to RMB 412,000 and the payback to 8.6 months. Here the centrifuge is included per the client’s flow diagram (orange nodes), so the quoted price is RMB 761,000.

06 · CAPACITY OPTIONS

Capacity options vs investment

The tier is locked once on-site measured throughput is confirmed. The three tiers differ only in main-unit size and piping/valve diameters; the process route and works are identical.

Three-tier configuration

10 / 20 / 30 t·d

Capacity	Main unit model	Main unit	Centrifuge	Auxiliaries	Eng. & service	Total investment	Investment per (t·d) (10k RMB)
10 t/d	ZSGJ-2	18.90	32.70	10.20	5.20	67.00	6.70
20 t/d recommended	ZSGJ-3	25.80	32.70	11.80	5.80	76.10	3.80
30 t/d	ZSGJ-4	31.60	32.80	12.90	7.00	84.30	2.81

Note: main-unit models and unit prices are linearly interpolated from the existing product line and must be confirmed after review against the measured daily throughput and feed composition (oil content, impurity rate). If the peak feed is well above the daily average, upsizing by one tier is recommended to avoid material buildup at peak.

07 · SAVINGS

Benefit calculation & payback

Based on 20 t/d and 330 operating days per year, the annual benefit after retrofit is RMB 574,400, corresponding to a processing-cost reduction of RMB 87.0 per ton.

Annual benefit breakdown

ANNUAL

Benefit item	Basis	10k RMB/yr
Extra crude oil	Oil yield +0.6 pt → 39.6 t/yr × RMB 7,250/t	28.71
Electricity saving	Net 22.5 kW × 10 h/d × 330 d × RMB 0.65/kWh	4.83
Labor saving	2 fewer staff × RMB 60,000/person·yr	12.00
Wastewater treatment fee	990 t/yr × RMB 95/t	9.40
Maintenance & wearing parts	Annual maintenance 45,000 → 20,000	2.50
Total annual benefit		57.44

Static payback period

15.9months

Retrofit investment 761,000 ÷ annual benefit 574,400

Annual benefitRMB 574,400
Cost reduction per tonRMB 87.0/t
Retrofit investmentRMB 761,000
Investment intensityRMB 38,000 per (t·d)
Operating days/yr330 days
Corresponding annual throughput6,600 t/yr

Sensitivity: oil-yield increase

SENSITIVITY

Assumption	Extra crude oil (t/yr)	Annual benefit (10k RMB)	Static payback (months)
+0.3 percentage points	19.8	43.09	21.2
+0.6 percentage points	39.6	57.44	15.9
+0.9 percentage points	59.4	71.80	12.7

Basis note: this calculation counts only the benefits directly produced by the retrofitted segment (oil, power, labor, wastewater, maintenance); it excludes the reuse value of the building space freed by removing the dewatering stage, as well as odor-control and environmental-compliance benefits. Crude oil is valued at RMB 7,250/t; the actual market price applies.

08 · SCHEDULE

Implementation & lead time

The key constraint is line shutdown time. All piping/valve prefabrication and electrical upgrade are done before shutdown; the on-site shutdown window is kept within 4 days.

Implementation milestones

~46 days · shutdown ≤ 4 days

No.	Milestone	Time	Days	Content / key points
1	Site survey & plan confirmation	D1 – D3	3	Confirm throughput, feed composition, existing controls and shutdown window
2	Equipment manufacture & delivery	D4 – D38	35	Main unit and centrifuge 35 days; pumps, valves and controls in parallel
3	Pre-fabrication before shutdown (parallel with manufacture)	D10 – D16	7	Piping/valve prefab, control-cabinet upgrade, foundation setting out; no production stop
4	Installation & tie-in	D39 – D42	4	Shutdown window ≤4 days; tie into cooking tank and three-phase section
5	Water & loaded commissioning	D43 – D45	3	No-load → water → loaded, gradually increasing load
6	Training & handover	D46	1	Operation, maintenance and wearing-part replacement training

Shutdown window

≤ 4days

Tie-in, positioning, piping and wiring are concentrated within 4 days; schedule during low-feed periods

Done before shutdown

70%

Piping/valve prefab, control-cabinet upgrade, foundation setting out and old-equipment disassembly prep are all done before shutdown

Commissioning method

Three stages

No-load → water → loaded; each stage runs stably before the next, avoiding a single full-load trial run

09 · PENDING INPUTS

Pending information & on-site photos

Once the following information is provided, this plan can be upgraded from "comparison and estimate" to a "ready-to-sign technical agreement + fixed quotation".

On-site photos: the 6 photos provided by the client have been received and organized into Section 02 "On-site photos · before retrofit", and can be used directly for the presentation.

Document checklist

6 items

No.	Item	Requirements	Purpose
1	Throughput & composition	Daily average and peak feed over the last 3 months; moisture, oil content and impurity share	Confirm main-unit model and centrifuge capacity
2	Cooking-tank spare capacity	Existing cooking-tank volume, heating method and residence time	Confirm whether new slurry can feed in directly
3	Dryer spare capacity	Existing dryer throughput and required moisture content	Confirm whether all centrifuge residue can be handled
4	Existing controls	Installed capacity, main incomer specs, control mode (local/central)	Define the control extension scope
5	Inorganic residue route	Whether incineration or off-site disposal qualification exists; daily output	Verify the drumming, transport and incineration chain
6	Shutdown arrangement	Acceptable shutdown days and time window	Lock the 4-day tie-in window

Next step: on-site photos are complete (see Section 02). Once measured throughput and the existing cooking-tank and dryer capacities are confirmed, we will turn this plan into a fixed quotation and equipment layout drawing ready for signing. If the client wants to see the result first, they can view the 720° panorama of the Liaocheng project after retrofit at the end of Section 04, or arrange a site visit to a nearby retrofitted project (Zaozhuang: formerly large-grab feeding + dewatering screws, now collection trucks tipping directly).