Composting Systems - Bulking Agents Dosing Classification Guide

Understanding the types and regularity of bulking agents for composting toilets through System Dosing Classifications will help you get the best form your system.

Dosing System Classes

Scoop Per Poop – When you do number 2’s you add a scoop or cupful of the appropriate bulking Agent

Type of system the meet this class

• Sun-Mar – All Air Flow and Self-Contained systems. Excludes Micro Flush systems
• Clivus Multrum – All CM8 to CM40 systems

Cover It Up – Each time the system is used, a large volume of bulking agents are used equivalently to cover the deposit.

Type of system the meet this class

• Bambooloo – All Bucket systems

Top It Up – When the composting mass inside the system has reduced in size to allow for more Bulking Agent you add to full to the desired manufactures level.

Type of system the meet this class

• EcoLet – All EcoLet 240 range (15e, 25e, 55ai, 65ai)

Just Add Some – The addition of Bulking Agents at intervals per manufactures guidelines and equivalently to the number of users.

Type of system the meet this class

• Sun-Mar – All Air Flow and Self-Contained systems. including Micro Flush systems.

Per Use – Just add a handful of Bulking Agents each time you use the system.

Type of system the meet this class

• Clivus Multrum – CM2 Chamber systems

Fill To Batch – Preload the system with the required amount of bulking Agent for the batching process. There is no need to add more bulking Agent until a new batch starts.

Type of system the meet this class

• Some mixing systems

When all composting systems are started there is a minimum amount of Bulking Agents are required to start the system.

It is important to use the best available source of Carbon materials to get effective performance out of your WCT System

Here are the recommended bulking agent lists

Clivus Multrum Systems

The Best Bulking Materials for Clivus Multrum Systems

Read this section as it has information relevant to the EcoLet ™ and Sun-Mar systems

The Clivus Multrum performs the best with a 20mm (large) wood shavings. These large wood shavings are available from suppliers around NZ typically in 20 and 100 kg bales, ranging from 30 to 100 dollars a bale.

The effect of the size and grade will achieve the following benefits;

The large wood shavings allow for;

• Air to move easily through the compost pipe inside the system
• The permeability of liquids to maintain a wet condition that should ideally be between 45 to 70% moisture content
• Air gaps leaving room for growth of Bacteria, Fungi and all other appropriate life forms for decay
• Compost to reduce in size (shrink) feeding down in through these gravity feed systems

WCTNZ have the following available for Clivus Multrum system (link to consumables)

• 100kg Bales
• 20kg Bales
• WCT Microbe Mix (used as a starter only)

CHOOSING A BULKING AGENT MATERIALS Clivus Multrum Consumables Link

Composting of human waste is a natural process and environmentally responsible. In keeping with this, the best choice for bulking agent materials is one that is readily available in your local area as a waste product from some other activity. Wood shavings have been found to be the ideal bulking material and provide consistent results. Wood shavings entrap air, are absorbent and do not become compacted as does other matter such as fine sawdust, newsprint or large quantities of grass clippings. A granular pine bark mulch is also suitable.

Wood shavings are the material recommended for Clivus Multrum, and are generally available from:

• Joinery workshops and some timber mills
• Commercial distributors that collect and package it
• Produce stores
• Pet shops
• Nursery and landscape suppliers

Please note: Wood shavings or sawdust must not be from treated timbers as the treatment process will hinder the growth of, or even poison, the microorganisms essential to the composting process.

However, if wood shavings are difficult to source in your area, read the following information to assist in choosing alternatives. The key characteristics of a good bulking material are:

• Dry, but readily absorbs moisture
• Has a high carbon/nitrogen ratio
• Remains friable, traps air and does not form a mat or ball when damp
• Is known to compost well, and has no chemical contaminants to affect the compost bacteria
• Availability and cost.

Composting with CARBON/NITROGEN (C:N) RATIO

Human waste has a carbon to nitrogen ratio of fewer than 10 parts carbon, whereas the optimum C:N ratio for composting human dejecta (waste) is 20-30 parts carbon. A bulking agent with a high C:N ratio is therefore preferred, as this allows a smaller quantity of the agent to be used in comparison with other materials.

Representative ratios for commonly available bulking agents are shown below to indicate the relative ability of the materials to provide additional carbon.

BULKING AGENT (DRY) CARBON/NITROGEN (C:N) RATIO;

• 650 Softwood shavings
• 550 Hardwood shavings
• 500 Newsprint
• 500 Softwood bark
• 450 Sawdust
• 130 Wheat straw
• 120 Rice hulls
• 80 Straw – general
• 60 Leaves and shrub trimmings

Not Recommended;

• 20 Grass clippings
• 20 Hay
• 20 Vegetable scraps

For example, to achieve the same C:N ratio in the compost pile around 10 kg of leaves would need to be added if used in place of 1kg of wood shavings. Mulched leaves and garden clippings can replace or supplement wood shavings as a bulking agent. Use material that has already started to compost, for example, leaf matter that has fallen on the ground and started to decompose. The fully decomposed matter is also ideal as this matter contains useful compost bugs and microorganisms along with a high level of good bacteria.

Please note: Fresh gum leaves do not make a good bulking agent, however, those that are partly decomposed and mixed with other composting matter can be good for the system. Material such as large woodchips, un-shredded newspaper, grass clippings, straw, long grasses, treated wood shavings or highly resinous wood should be avoided as they take a longer time to break down or are unsuitable to compost.

Finely chopped vegetable scraps and peelings may be added to the process as long as they are not too wet and have been kept in an airtight container to prevent insect infestations. However, because of their high nitrogen content, the addition of these scraps will require more bulking agent materials, not less unless earthworms are also used. Addition of these materials will reduce the working capacity of the composting system available for processing human wastes.

Clivus Multrum - CM2 Clivus Multrum Consumables Link

If you have a CM2 system, there is a large range of bulking agent materials that can be used. Please refer to the respective manuals and read the section above to get a better idea of the nature of Carbon to Nitrate ratios to choose your bulking materials for effective composting.
Please note: that these systems are a batching type and complete composting is done in two stages.

EcoLets™ Systems

Best bulking agent for Ecolet Systems

The EcoLets™ performs the best with a 10mm (medium) wood shavings. These medium-sized wood shavings are available from suppliers around NZ typically in 20 kg and 100 kg bales, ranging from 30 to 100 dollars a bale.
The EcoLets™ (heated) systems must have a mixture too perform there best both in the friability for the mixing of the compost and for moisture retention to prevent the system from drying out.

There are three types of bulking agent materials that benefit the moisture control the EcoLets™ systems.

1. Peat Moss - this material is easily compostable and has a high ability to absorb moisture. It is readily available from suppliers but here at WCTNZ, we do not consider it as sustainable as Coco Peat
2. Coco Peat - this material is a little harder to break down but has a very high ability to absorb moisture. It is not readily available from suppliers at a cost-effective price so we at WCTNZ do supply this product at a lockdown price. This product is very sustainable as it is a by-product of Coconut plantations that would have to be dumped otherwise
3. Wood Shavings – this material is probably a must when it comes to the composting systems as it provides the best source of Carbon materials for microbes to feed on

Make your own bulking agent mixtures

Bulking material Mixture Recipe:

Fine Grade Peat Moss 30% + Fine Grade Coco Peat 30% + Untreated Wood shavings 40%
We have found this formula very effective and matches closely the Manufacture bulking Agent.

WCTNZ have the following available for Ecolet systems EcoLet™ Consumables Link

Mix You Own Sun-Mar Bulking Agents

• 100kg Bales
• 20kg Bales
• Coco Peat 5 kg Bricks

Buy Pre-Mix

• WCT Eco Mix - 30 Litres
• WCT Microbe Mix (used as a starter only)

If you have any of the EcoLets™ NE systems, there is a large range of bulking agent materials that can be used. Please refer to the respective manuals and read the section on Clivus Multrum systems above to get a better idea of the nature of Carbon to Nitrate ratios to choose your bulking materials for effective composting.
Please note: that these systems are a batching type and complete composting is done in two stages.

Sun-Mar Systems

Best bulking agent for Sun-Mar Systems

The Sun-Mar performs the best with a 10mm (medium grade) wood shavings (special grade). These medium-sized wood shavings are available from WCTNZ or Pure Pine and are around NZ$30 per bale.

This special grade wood shaving has been selected because of it course property that works best in the Sun-Mar Bio-Drum™ to mix and reduce any blockages of the moisture management system.

There are two types of Bulking additive materials that benefit the moisture control the Sun-Mar systems

Peat Moss - this material is easily compostable and has a high ability to absorb moisture. It is readily available from suppliers but here at WCTNZ, we do not consider it as sustainable as Coco Peat
Coco Peat - this material is a little harder to break down but has a very high ability to absorb moisture. It is not readily available from suppliers at a cost-effective price so we at WCTNZ do supply this product at a lockdown price. This product is very sustainable as it is a by-product from Coconut plantations that would have to be dumped otherwise.

Make your own bulking agent mixtures

Sun-Mar Bulking Agent Mixture Recipes:

• For (Dry Toilet) self-contained and Air-Flow - A/F Models
  Corse Grade Coco Peat 40% + Untreated Special Grade Wood shavings 60%
• For (Wet Toilet) Micro-Flush - M/F Models
  Corse Grade Coco Peat 20% + Untreated Special Grade Wood shavings 80%

WCTNZ have the following available for Sun-Mar systems Sun-Mar Consumables Link

Mix You Own Sun-Mar Bulking Agents

• 20kg Bales (special grade wood shavings)
• Coco Peat 5 kg Bricks

Buy Pre-Mix

• WCT Sun Mix - 30 Litres (with additives)
• WCT Microbe Mix (used as a starter only)