WINETECH Technical Yearbook 2019

pond that drains into an aerobic pond. The water is used to irrigate pastures. Up to 400 kg per ha per year of N can be applied via the irrigation water. Nutrients in the wastewater promote the growth of the pastures. However, e l evated P i n the soil can be a concern. Approx imate l y 660 mm of water is applied to the pastures per year. MUNICIPAL WASTEWATER TREATMENT PLANTS NEAR PALMERSTON NORTH Feilding T h e s e wa g e g o e s t o t h e t r e a t me n t p l a n t . Historically, the resource consent was to the river, but now it will be to land as well. At the treatment plant, there is a digestion tank. The wastewater dam has submerged aeration (Photo 5). Thus, in the dam bubbles are continuously been blown up through the water. The sludge is c omp o s t e d ( P h o t o 6 ) . C u r r e n t l y, r e s e a r c h i s being done to see what combination of materials

will yield the best compost. F o r c omp o s t i n g , t h e material must be contained on a concrete pad. It is also important to turn the compost heaps properly. The compost can be used by garden centres or the council. In New Zealand, a cut and carry process (Photo 7) is used to make straw. The advantage of this is that animals are kept off the land. Himatangi Beach In this area, there is an abundance of l and and the terrain is very flat. The water table is very sha l l ow. I t can become very dry over summer. The municipal treatment system at Himatangi Beach is a basic, simple system which does not requ i re much management (Photo 8A-C). The municipal wastewater is collected in a dam, which has a floating wetland. The water is irrigated to grazed pastures with a number o f d i f f e r e n t i r r i ga t i on systems. One hundred and fifty kilograms of N can be

A

B

C

D

PHOTO 8. Irrigation of municipal wastewater to grazed pasture (A, B and C) at Himatangi Beach near Palmerston North. Notice the ponding in Photo 8D.