Dear SuSanA members,
I’m new to the forum and would like to share what our team is working on and ask for specific advice.

Pass NetZero is a non-profit that coordinates postgraduate research with LUANAR (Malawi) and NUST (Namibia) on using aquatic macrophytes to improve wastewater treatment and reduce greenhouse gas emissions from polluted water bodies. Two sites are at the heart of the work:

• Kauma Sewage Treatment Plant, Lilongwe (Malawi): planted waste stabilisation ponds. Working with the Lilongwe Water Board, a Master’s student at LUANAR is testing Typha and Phragmites planted in the shallow ponds as a simple, low-cost upgrade to existing waste stabilisation ponds. The approach could be replicated in other ponds in Lilongwe and other Malawian towns.
• Goreangab Dam and Gammams Water Care Works, Windhoek (Namibia): floating treatment wetlands. NUST students are trialling floating treatment wetlands on an urban reservoir, and testing Cyperus papyrus and C. alternifolius for heavy metal uptake.

We’d especially value experience on five questions:

1. Contaminated biomass and sludge. At Kauma, harvested plants and pond sludge are likely to carry heavy metals, and we know some residents already divert pond water and soil to fertilise crops. Has anyone set safe handling or end-use rules for macrophyte biomass from sewage ponds? We have ruled out anaerobic digestion because of the leakage risk, so we’re interested in other routes, including safe disposal.
2. Reducing aeration costs. Mechanical aeration at Kauma is expensive because of electricity costs. Is there field evidence that planted zones or floating wetlands in waste stabilisation ponds can reduce the aeration needed, or partly replace it?
3. Floating wetlands on a reservoir. At Goreangab, we want to keep sediment build-up low because it reduces storage capacity, so we favour regular harvesting. What harvest frequency and mat coverage have worked for floating treatment wetlands in warm climates, and how did others anchor and maintain them on open water?
4. Low-cost methane sensors. Has anyone tested the inexpensive CH₄ / greenhouse gas sensors sold online (metal-oxide or NDIR types) on ponds or wetlands? Are they reliable enough to be worth using, even just to compare sites?
5. Submerged species. So far we have only tested emergent and floating plants. Has anyone used submerged macrophytes in treatment ponds, and how did they cope with turbidity and high nutrient loads.

A practical question: we’d like Pass NetZero to become a SuSanA partner organisation, but the partner application page won’t load for me. Could the Secretariat or another member point me to the current way to apply?

Other work in our programme
Beyond the two main sites, smaller studies and new programmes are under way. We’d be happy to connect with anyone working on similar topics:

• Seaweed (Ulva rigida), Lüderitz, Namibia: carbon sequestration potential and possible uses of the biomass, including as a cement additive (NUST).
• Spirulina (Arthrospira platensis) cultivation, Bunda Fish Farm, Malawi: a study at LUANAR.
• Okavango Delta, Botswana: a new programme with the University of Botswana on natural wetland processes, including methane emissions.
• Programmes in development with partners in Togo, Zambia and Zimbabwe.

If any of these overlap with your work, feel free to reply here or contact us through passnetzero.org .

Thanks in advance. We’ll report back here as the students’ results come in.